Unnamed: 0
int64 0
2.34M
| title
stringlengths 5
21.5M
| abst
stringlengths 1
21.5M
|
|---|---|---|
2,337,800 |
Molecular analysis of Iranian families with sickle cell disease.
|
Sickle hemoglobin is a mutant hemoglobin in which valine has been substituted for the glutamic acid normally at the sixth amino acid of the beta-globin chain. Detection of the single base pair mutation at codon 6 of the beta-globin gene is important for the prenatal diagnosis of sickle cell anemia and sickle cell disease. Application of the polymerase chain reaction technology to detect sickle cell patients and heterozygous carriers in a group of patients suspected for sickle cell disease was carried out. The sample was composed of 52 normal individuals and 52 unrelated outpatients who were attending the Hematology Research Center. All patients were interviewed. Results of their medical histories, physical examination, and the hematological analysis were recorded. The blood samples were collected in EDTA and genomic DNA was extracted from leukocytes. An amplified 110 base pair fragment of the beta-globin gene containing codon 6, was digested with the restriction enzyme MS II, and electerophoresed in 3 per cent agarose. We have established the technical condition for detection of sickle cell disease using a PCR assay. Fifteen patients having haemoglobin (Hb SS) and 37 patients in the heterozygous state (Hb AS) were identified. We confirm that the normal controls have the Hb AA genotype. The standardization of a highly sensitive and specific diagnostic test for sickle cell disease permitted us to identify the normal controls, the homozygotes and heterozygotes. This amplification method is rapid, sensitive and simple, and also has application research that is important for the prenatal diagnosis of sickle cell disease.
|
2,337,801 |
Accuracy of MSI testing in predicting germline mutations of MSH2 and MLH1: a case study in Bayesian meta-analysis of diagnostic tests without a gold standard.
|
Microsatellite instability (MSI) testing is a common screening procedure used to identify families that may harbor mutations of a mismatch repair (MMR) gene and therefore may be at high risk for hereditary colorectal cancer. A reliable estimate of sensitivity and specificity of MSI for detecting germline mutations of MMR genes is critical in genetic counseling and colorectal cancer prevention. Several studies published results of both MSI and mutation analysis on the same subjects. In this article we perform a meta-analysis of these studies and obtain estimates that can be directly used in counseling and screening. In particular, we estimate the sensitivity of MSI for detecting mutations of MSH2 and MLH1 to be 0.81 (0.73-0.89). Statistically, challenges arise from the following: (a) traditional mutation analysis methods used in these studies cannot be considered a gold standard for the identification of mutations; (b) studies are heterogeneous in both the design and the populations considered; and (c) studies may include different patterns of missing data resulting from partial testing of the populations sampled. We address these challenges in the context of a Bayesian meta-analytic implementation of the Hui-Walter design, tailored to account for various forms of incomplete data. Posterior inference is handled via a Gibbs sampler.
|
2,337,802 |
Identifying future models for delivering genetic services: a nominal group study in primary care.
|
To enable primary care medical practitioners to generate a range of possible service delivery models for genetic counselling services and critically assess their suitability.</AbstractText>Modified nominal group technique using in primary care professional development workshops.</AbstractText>37 general practitioners in Wales, United Kingdom too part in the nominal group process. The practitioners who attended did not believe current systems were sufficient to meet anticipated demand for genetic services. A wide range of different service models was proposed, although no single option emerged as a clear preference. No argument was put forward for genetic assessment and counselling being central to family practice, neither was there a voice for the view that the family doctor should become skilled at advising patients about predictive genetic testing and be able to counsel patients about the wider implications of genetic testing for patients and their family members, even for areas such as common cancers. Nevertheless, all the preferred models put a high priority on providing the service in the community, and often co-located in primary care, by clinicians who had developed expertise.</AbstractText>There is a need for a wider debate about how healthcare systems address individual concerns about genetic concerns and risk, especially given the increasing commercial marketing of genetic tests.</AbstractText>
|
2,337,803 |
Genetic analysis of modern and historical burned human remains.
|
Burning of corpses is a well-known funeral procedure that has been performed for a long time in many cultures. Nowadays more and more corpses are burned in crematories and buried in urns, often for practical and financial reasons. In some scientific, criminal or civil cases even after cremation there is the need of genetic investigations for identification or paternity testing. Furthermore, burned remains are the only remains left in North Europe from 1200 BC to 500 AD. This makes genetic investigation of those materials interesting for anthropological reasons. We present on one hand a systematic investigation of 10 corpses before and after the cremation and on the other hand the analysis of seven historical remains representing the bronze age. We chose the ground bone powder and the less destroyed bone parts respectively and employed a slightly modified commercially available DNA extraction method. The presence of human nuclear and mitochondrial DNA was tested by a simple but highly sensitive Duplex-PCR. DNA quantification was done using real time PCR, and genetic typing was tried out using the AmpFISTR Identifiler Multiplex Kit, followed by an automatic analysis on an AbiPrism310.
|
2,337,804 |
Candidate-gene screening and association analysis at the autism-susceptibility locus on chromosome 16p: evidence of association at GRIN2A and ABAT.
|
Autism is a highly heritable neurodevelopmental disorder whose underlying genetic causes have yet to be identified. To date, there have been eight genome screens for autism, two of which identified a putative susceptibility locus on chromosome 16p. In the present study, 10 positional candidate genes that map to 16p11-13 were examined for coding variants: A2BP1, ABAT, BFAR, CREBBP, EMP2, GRIN2A, MRTF-B, SSTR5, TBX6, and UBN1. Screening of all coding and regulatory regions by denaturing high-performance liquid chromatography identified seven nonsynonymous changes. Five of these mutations were found to cosegregate with autism, but the mutations are not predicted to have deleterious effects on protein structure and are unlikely to represent significant etiological variants. Selected variants from candidate genes were genotyped in the entire International Molecular Genetics Study of Autism Consortium collection of 239 multiplex families and were tested for association with autism by use of the pedigree disequilibrium test. Additionally, genotype frequencies were compared between 239 unrelated affected individuals and 192 controls. Patterns of linkage disequilibrium were investigated, and the transmission of haplotypes across candidate genes was tested for association. Evidence of single-marker association was found for variants in ABAT, CREBBP, and GRIN2A. Within these genes, 12 single-nucleotide polymorphisms (SNPs) were subsequently genotyped in 91 autism trios (one affected individual and two unaffected parents), and the association was replicated within GRIN2A (Fisher's exact test, P<.0001). Logistic regression analysis of SNP data across GRIN2A and ABAT showed a trend toward haplotypic differences between cases and controls.
|
2,337,805 |
Familial vesicoureteral reflux: testing replication of linkage in seven new multigenerational kindreds.
|
Vesicoureteral reflux (VUR) (OMIM %193000), a common cause of childhood renal failure, is strongly influenced by hereditary factors. Familial VUR most closely conforms to autosomal-dominant inheritance, but because of variable penetrance and expressivity, large multigenerational pedigrees tractable to linkage analysis have been difficult to ascertain. A single genome-wide study of familial VUR has demonstrated linkage to chromosome 1p13, with 78% locus heterogeneity. Previous studies in humans have also suggested loci on chromosomes 6p21, 10q26, and 19q13, whereas mutations in ROBO2 were recently reported in some patients with VUR. Replication of these studies was attempted in seven previously undescribed families from Italy and the United States. Simulation studies, assuming 50% locus heterogeneity, showed that these kindreds had 85% power to replicate linkage and 53% power to achieve genome-wide significance at candidate intervals. Thirty-five markers on chromosomes 1p13, 3p12, 6p21, 10q26, and 19q13 were genotyped and analysis of linkage under a variety of models was performed. Parametric analysis excluded linkage to all candidate loci under genetic homogeneity; moreover, the data did not support statistically significant linkage under models of locus heterogeneity. Similarly, nonparametric, allele-sharing analysis did not reveal any evidence of linkage at any of the loci tested. Thus, despite sufficient power, linkage of familial VUR to previously reported candidate intervals could not be replicated. These data demonstrate substantial genetic heterogeneity of VUR and suggest that mapping strategies relying on a large number of kindreds or single "loaded" pedigrees will be most effective to achieve replication or detection of linkage.
|
2,337,806 |
Gene SNPs and mutations in clinical genetic testing: haplotype-based testing and analysis.
|
Haplotype-based analysis using high-density single nucleotide polymorphism (SNP) markers have gained increasing attention in evaluating candidate genes in various clinical situations. For example, haplotype information is useful for predicting the severity and prognosis of certain genetic disorders. The intragenic cis-interactions between the common polymorphisms and the pathogenic mutations of prion protein (PRNP) and cystic fibrosis transmembrane conductance regulator (CFTR) genes greatly influence the phenotypes and the disease penetrance of hereditary Creutzfeldt-Jakob disease and cystic fibrosis. Merits of haplotype study are more evident in the fine mapping of complex diseases and in identifying genetic variations that influence individual's response to drugs. Knowledge-based approaches and/or linkage analyses using SNP tagged haplotypes are effective tools in detecting genetic associations. For example, haplotype studies in the inflammatory bowel disease susceptibility loci revealed diverse cis and trans gene-gene interactions, which can affect the clinical outcomes. Although currently, we have very limited knowledge on haplotype-phenotypic characterizations of most genes, these examples demonstrate that increased understanding of the clinically relevant haplotypes will provide better results in the diagnosis and possibly in the treatment of both monogenic and polygenic diseases.
|
2,337,807 |
Single nucleotide polymorphisms in clinical genetic testing: the characterization of the clinical significance of genetic variants and their application in clinical research for BRCA1.
|
Clinical genetic testing is increasingly employed in the medical management of cancer patients. These tests support a variety of clinical decisions by providing results that indicate risk for future disease, confirmation of diagnoses, and more recently, therapeutic selection and prognosis. Most genetic variation detected during clinical testing involves single nucleotide polymorphisms (SNPs). Continued advances in the technologies of genetic analyses make these tests increasingly sensitive, cost-effective and timely, which contribute to their increased utilization. Conversely, it has proven difficult to characterize the clinical significance of genetic variants that do not obviously truncate the open reading frames of genes. These genetic variants of uncertain clinical significance diminish the value of genetic test results. This article highlights a variety of approaches that have emerged from research in diverse disciplines to solve the problem, including the application of information about common SNPs in multiple methods to better characterize clinically uncertain variants. Hereditary breast/ovarian cancer, and in particular BRCA1, provides a framework for this discussion. BRCA1 is particularly interesting in this respect since clinical genetic testing by direct DNA sequencing for over 50,000 patients in North America has revealed approximately 1500 genetic variants to date. This large data set combined with the clinical significance of BRCA1 have resulted in research groups selecting BRCA1 as a preferred gene to evaluate novel methods in this field. Finally, the lessons learned through work with BRCA1 are highly applicable to many other genes associated with cancer risk.
|
2,337,808 |
Mutation detection, interpretation, and applications in the clinical laboratory setting.
|
Mutation detection plays an increasingly significant role in clinical diagnostic testing, posing formidable challenges for laboratories. The expanding indications for clinical molecular testing and the nuances of interpreting test results are discussed. Methods for screening mutation detection platforms and monitoring assay reliability are presented, and results of platform comparisons are described. The potential for irrevocable medical interventions following a positive mutation analysis is highlighted to stress the imperative for accuracy in mutation detection and vigilance in the clinical arena.
|
2,337,809 |
Assessment of two flexible and compatible SNP genotyping platforms: TaqMan SNP Genotyping Assays and the SNPlex Genotyping System.
|
In this review we describe the principles, protocols, and applications of two commercially available SNP genotyping platforms, the TaqMan SNP Genotyping Assays and the SNPlex Genotyping System. Combined, these two technologies meet the requirements of multiple SNP applications in genetics research and pharmacogenetics. We also describe a set of SNP selection tools and validated assay resources which we developed to accelerate the cycle of experimentation on these platforms. Criteria for selecting the more appropriate of these two genotyping technologies are presented: the genetic architecture of the trait of interest, the throughput required, and the number of SNPs and samples needed for a successful study. Overall, the TaqMan assay format is suitable for low- to mid-throughput applications in which a high assay conversion rate, simple assay workflow, and low cost of automation are desirable. The SNPlex Genotyping System, on the other hand, is well suited for SNP applications in which throughput and cost-efficiency are essential, e.g., applications requiring either the testing of large numbers of SNPs and samples, or the flexibility to select various SNP subsets.
|
2,337,810 |
Genes, genomes and identity. Projections on matter.
|
This paper aims to show that references to genes and genomes are counterproductive in legal and political understandings of what it is to be human and a unique individual. To support this claim, I will give a brief overview of the many incompatible meanings the term 'identity' has gathered in reference to genes or genome in the contexts of biology and family ancestry, personal identity, species identity. One finds various and incompatible understandings of these expressions. While genetics is usually considered to deliver definitive knowledge about history and the future, genomics seems to work with more complicated relations between DNA, inheritance and phenotype. In genomics, 'identity' is no longer about identification and status markers but about individualization. Regulatory and legal documents project from traits to genomes, implying that individuality is at least represented, if not created, in a unique genome. Boundaries between humans and other animals, between different 'kinds' of humans, and between all individual humans are re-established via reference to the chemical matter of DNA. My analysis will show how this trend is a reactionary response to modern understandings of identities as social products and that it ignores new biomedical understandings of human bodies.
|
2,337,811 |
Diagnosis of Pelizaeus-Merzbacher disease: detection of proteolipid protein gene copy number by real-time PCR.
|
Duplication of the proteolipid protein gene (PLP1) is the most frequent cause of Pelizaeus-Merzbacher disease (PMD), a severe X-linked myelination disorder. We developed an assay for the detection of the PLP1 gene dosage by real-time quantitative PCR using the ABI Prism 7700 Sequence Detection System and the TaqMan chemistry. Copy number of the PLP1 gene was determined by the standard curve method using GAPDH as the reference gene. The assay was tested both on 50 normal controls and on 20 subjects whose PLP1 gene copy number was previously determined by quantitative fluorescent multiplex PCR. The procedure confirmed the expected results both on the male and female normal controls as well as on the 20 subjects previously tested. Ratios corresponding to the presence of one, two or three PLP1 gene copies, distributed in three non-overlapping ranges, were obtained by real-time PCR analysis. Subsequently, 29 DNA samples of putative PMD patients and possible female carriers, with unknown PLP1 gene dosage, were analysed. Five affected males carrying the PLP1 gene duplication and four female heterozygotes carrying three PLP1 gene copies were identified among them. The method is suitable for the identification of affected male patients and female carriers. Specific ranges are widely spaced, ensuring a correct assignment of the PLP1 gene copy number.
|
2,337,812 |
Hardy-Weinberg equilibrium in genetic association studies: an empirical evaluation of reporting, deviations, and power.
|
We evaluated the testing and reporting of Hardy-Weinberg equilibrium (HWE) in recent genetic association studies, detected how frequently HWE was violated and estimated the power for HWE testing in this literature. Genetic association studies published in 2002 in Nature Genetics, American Journal of Human Genetics, and American Journal of Medical Genetics were assessed. Data were analyzed on 239 biallelic associations using 154 distinct genotype distribution data sets where HWE could be tested. Any information on HWE was given only for 150 (62.8%) associations (92 (59.7%) data sets). Reanalysis of the data showed significant deviation from HWE in the disease-free controls of 20 associations (13 data sets), but only four of them (two data sets) were admitted in the published articles. Another four deviations (in two data sets) were observed in the combined sample of cases and controls of studies where both cases and controls were diseased, and none were reported in the papers. In all six tested multiallelic associations (six data sets), there was violation of HWE, but this was not admitted in the published articles. Power calculations showed that most studies conforming to HWE simply were largely underpowered to detect HWE deviation; for example, power to detect an inbreeding of magnitude F=0.10 exceeded 80% in only 11 (7%) of the data sets being tested. This empirical evidence suggests that, even in high profile genetics journals, testing and reporting for HWE is often neglected and deviations are rarely admitted in the published reports. Moreover, power is limited for HWE testing in most current genetic association studies.
|
2,337,813 |
Racial differences in the use of BRCA1/2 testing among women with a family history of breast or ovarian cancer.
|
Given the current context of racial disparities in health and health care and the historical context of eugenics, racial disparities in the use of genetic susceptibility testing have been widely anticipated. However, to our knowledge there are no published studies examining the magnitude and determinants of racial differences in the use of genetic susceptibility testing.</AbstractText>To investigate the relationship between race and the use of BRCA1/2 counseling among women with a family history of breast or ovarian cancer and to determine the contribution of socioeconomic characteristics, cancer risk perception and worry, attitudes about genetic testing, and interactions with primary care physicians to racial differences in utilization.</AbstractText><AbstractText Label="DESIGN, SETTING, AND PARTICIPANTS" NlmCategory="METHODS">Case-control study (December 1999-August 2003) of 408 women with a family history of breast or ovarian cancer, of whom 217 underwent genetic counseling for BRCA1/2 testing (cases) and 191 women did not (controls). Participants received primary care within a large health system in greater Philadelphia, Pa.</AbstractText>Probability of carrying a BRCA1/2 mutation, socioeconomic characteristics, perception of breast and ovarian cancer risk, worry about breast and ovarian cancer, attitudes about BRCA1/2 testing, and primary care physician discussion of BRCA1/2 testing were measured prior to undergoing BRCA1/2 counseling for cases and at the time of enrollment for controls.</AbstractText>African American women with a family history of breast or ovarian cancer were significantly less likely to undergo genetic counseling for BRCA1/2 testing than were white women with a family history of breast or ovarian cancer (odds ratio, 0.22; 95% confidence interval, 0.12-0.40). This association persisted after adjustment for probability of BRCA1/2 mutation, socioeconomic characteristics, breast and ovarian cancer risk perception and worry, attitudes about the risks and benefits of BRCA1/2 testing, and primary care physician discussion of BRCA1/2 testing (adjusted odds ratio for African American vs white, 0.28; 95% confidence interval, 0.09-0.89).</AbstractText>Racial disparities in the use of BRCA1/2 counseling are large and do not appear to be explained by differences in risk factors for carrying a BRCA1/2 mutation, socioeconomic factors, risk perception, attitudes, or primary care physician recommendations. The benefit of predictive genetic testing will not be fully realized unless these disparities can be addressed.</AbstractText>
|
2,337,814 |
Sarcocystis neurona-associated meningoencephalitis and description of intramuscular sarcocysts in a fisher (Martes pennanti).
|
A free-ranging juvenile fisher (Martes pennanti) with ataxia, lethargy, stupor, and intermittent, whole-body tremors was examined postmortem. Microscopically, the fisher had protozoal meningoencephalitis caused by Sarcocystis neurona, which was confirmed by immunohistochemistry, polymerase chain reaction (PCR) and restriction fragment length polymorphism testing, and genetic sequencing. Sarcocysts found in the skeletal muscle of the fisher were negative for S. neurona by PCR, but were morphologically similar to previous light and electron microscopy descriptions of S. neurona. This is the first report of clinical neural S. neurona infection in a fisher.
|
2,337,815 |
Replication-competent adenovirus formation in 293 cells: the recombination-based rate is influenced by structure and location of the transgene cassette and not increased by overproduction of HsRad51, Rad51-interacting, or E2F family proteins.
|
Propagation of E1 region replacement adenovirus vectors in 293 cells results in the rare appearance of replication-competent adenovirus (RCA). The RCA genome contains E1 DNA acquired from the 293 cellular genome. The Luria-Delbruck fluctuation test was adapted to measure RCA formation rates. To test if structure affected rate, we measured rates during the production of adenovirus vectors with genomes containing three different expression cassette arrangements. The vectors had different extents of sequence identity with integrated Ad5 DNA of 293 cells and had different distributions of identity flanking the expression cassettes. Empty cassette vector RCA rates ranged from 2.5 x 10(-8) to 5.6 x 10(-10). The extent of sequence identity was not an accurate RCA rate predictor. The vector with the highest RCA rate also had the least overall sequence identity. To define factors controlling RCA generation, adenovirus vectors expressing E2F family proteins, known to modulate recombination gene expression, and overexpressing the human Rad51 recombination protein were analyzed. Compared to their corresponding empty vectors, RCA rates were not increased but were slightly decreased. Initial results suggested expression cassette orientation and/or transcription direction as potential RCA rate modifiers. Testing adenovirus vectors with identical transgene cassettes oriented in opposite directions suggested that transcription direction was not the basis of these rate differences. Thus, the overall structure and location of the transgene cassette had the largest effect on RCA rate. The RCA fluctuation test should be useful for investigators who require accurate measurements of targeted recombination and the probability of RCA formation during stock production.
|
2,337,816 |
Seliciclib (CYC202 or R-roscovitine), a small-molecule cyclin-dependent kinase inhibitor, mediates activity via down-regulation of Mcl-1 in multiple myeloma.
|
Cyclin-dependent kinase (CDK) inhibitors have the potential to induce cell-cycle arrest and apoptosis in cancer cells. Seliciclib (CYC202 or R-roscovitine) is a potent CDK inhibitor currently undergoing phase-2 clinical testing in lung and B-cell malignancies. Here we studied the in vitro cytotoxic activity of seliciclib against multiple myeloma (MM) cells. Our data demonstrate that seliciclib has potent cytotoxicity against MM cells that are both sensitive and resistant to conventional therapy as well as primary MM cells from patients. Cell-cycle and Western blot analysis confirmed apoptosis. Importantly, seliciclib triggered a rapid down-regulation of Mcl-1 transcription and protein expression independent of caspase cleavage. Adherence of MM cells to bone marrow stromal cells (BMSCs) induced increased Mcl-1 expression associated with signal transducer and activator of transcription 3 (STAT3) phosphorylation, which was inhibited in a time- and dose-dependent manner by seliciclib. Furthermore, seliciclib inhibited interleukin 6 (IL-6) transcription and secretion triggered by tumor cell binding to BMSCs. Up-regulation of Mcl-1 expression in cocultures was only partially blocked by neutralizing antibody to IL-6, suggesting alternative mechanisms of Mcl-1 modulation by seliciclib. Finally, combination studies of seliciclib with doxorubicin and bortezomib show in vitro synergism, providing the rationale for testing these drug combinations to improve patient outcome in MM.
|
2,337,817 |
A novel susceptibility locus at 2p24 for generalised epilepsy with febrile seizures plus.
|
Generalised epilepsy with febrile seizures plus (GEFS+) is a clinically and genetically heterogeneous epilepsy syndrome. Using positional cloning strategies, mutations in SCN1B, SCN1A, and GABRG2 have been identified as genetic causes of GEFS+. In the present study, we describe a large four generation family with GEFS+ in which we performed a 10 cM density genome-wide scan. We obtained conclusive evidence for a novel GEFS+ locus on chromosome 2p24 with a maximum two point logarithm of the odds (LOD) score of 4.22 for marker D2S305 at zero recombination. Fine mapping and haplotype segregation analysis in this family delineated a candidate region of 3.24 cM, corresponding to a physical distance of 4.2 Mb. Linkage to 2p24 was confirmed (p = 0.007) in a collection of 50 nuclear and multiplex families with febrile seizures and epilepsy. Transmission disequilibrium testing and association studies provided further evidence (p < 0.05) that 2p24 is a susceptibility locus for febrile seizures and epilepsy. Furthermore, we could reduce the candidate region to a 2.14 cM interval, localised between D2S1360 and D2S2342, based upon an ancestral haplotype. Identification of the disease gene at this locus will contribute to a better understanding of the complex genetic aetiology of febrile seizures and epilepsy.
|
2,337,818 |
Genetic testing: who should do the testing and what is the role of genetic testing in the setting of celiac disease?
|
Celiac disease is a remarkable and common immune-mediated disorder determined by both the presence of characteristic HLA alleles (DQ2 and DQ8) and one of the best characterized environmental factors (gliadin) for any common autoimmune disease. The discovery of transglutaminase autoantibodies and the development of assays for these antibodies has allowed the identification of a large number of asymptomatic individuals with autoimmunity and intestinal biopsy evidence of celiac lesions. Further understanding of the sequelae of asymptomatic celiac disease, and the interaction between genetic susceptibility and environmental factors, are likely to alter fundamentally both genetic screening for celiac disease and its therapy.
|
2,337,819 |
[Myotonic dystrophy type 1 in cataract patients: molecular diagnosis for screening and genetic counseling].
|
To detect MD1 premutation and full mutation carriers among cataract patients and offer familial genetic counseling.</AbstractText>We studied the DNA of 60 selected cataract patients through polymerase chain reaction analysis. This study was performed at the "Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto" where selected patients had been examined at the Cataract Outpatient Clinic from 01/01/1982 to 30/06/1995. Selection criteria were age under 55 with no obvious precipitating factor, except diabetes mellitus type 2, with or without neuromuscular signs suggestive of myotonic dystrophy.</AbstractText>Three patients were found to have a full mutation corresponding to 5% of the group. Additional affected individuals were found among patients' relatives. No premutation was found.</AbstractText>These results emphazise the importance of screening for MD1 gene carriers among cataract patients, and further genetic counselling.</AbstractText>
|
2,337,820 |
PRNP H187R mutation associated with neuropsychiatric disorders in childhood and dementia.
|
Described is a large family with an autosomal dominant dementia associated with an H187R mutation in the prion protein gene (PRNP). Clinical features include neuropsychiatric disturbances in childhood and adolescence, dementia in young adulthood with frontotemporal manifestations, and long disease duration. Neuropathology revealed atrophy and mild gliosis, whereas prion protein analysis revealed an abnormal conformer with unusual sensitivity to protease digestion. Mutations in PRNP may cause neuropsychiatric disorders that predate dementia by many years.
|
2,337,821 |
The clinical and genetic spectrum of spinocerebellar ataxia 14.
|
Spinocerebellar ataxia 14 (SCA14) is associated with missense mutations in the protein kinase C gamma gene (PRKCG), rather than a nucleotide repeat expansion. In this large-scale study of PRKCG in patients with ataxia, two new missense mutations, an in-frame deletion, and a possible splice site mutation were found and can now be added to the four previously described missense mutations. The genotype/phenotype correlations in these families are described.
|
2,337,822 |
Glycine decarboxylase mutations: a distinctive phenotype of nonketotic hyperglycinemia in adults.
|
Three unrelated adult patients with mild hyperglycinemia, infantile hypotonia, mental retardation, behavioral hyperirritability, and aggressive outbursts were screened for glycine decarboxylase (GLDC) mutations; two novel missense mutations (A389V and R739H) were found. Both mutations had a 6 to 8% of normal GLDC activities when expressed in COS7 cells.
|
2,337,823 |
A new dominant distal myopathy affecting posterior leg and anterior upper limb muscles.
|
To report a dominant, slowly progressive early onset distal myopathy with sparing of the tibialis anterior.</AbstractText>Twelve affected and two possibly affected members from an Australian kindred were examined and investigated by EMG, imaging studies, histopathology, and genetic analysis.</AbstractText>Affected patients had a slowly progressive condition with symmetric, distal weakness and wasting of the anterior upper and posterior lower limbs, with sparing of tibialis anterior, even in advanced disease. All patients remained ambulant and there was no evidence of cardiac or respiratory muscle involvement. Serum creatine kinase levels were either normal or mildly elevated. Imaging studies showed widespread involvement of the posterior and lateral leg compartments. Proximal muscles were radiologically abnormal only in advanced disease. Muscles that were mildly affected clinically appeared normal on imaging. EMG in nine patients showed widespread myopathic changes. Muscle histopathology in four patients showed either end stage muscle or nonspecific myopathic findings without inflammation or vacuoles. Microsatellite markers for distal myopathy loci were analyzed and all known distal myopathy phenotype genes and linkage regions were formally excluded by multipoint analysis.</AbstractText>The affected patients in this kindred display a clinically distinct myopathy, with selective involvement of posterior lower and anterior upper limb muscles. The genetic analysis suggests the existence of one more distal myopathy locus.</AbstractText>
|
2,337,824 |
Autosomal recessive mitochondrial ataxic syndrome due to mitochondrial polymerase gamma mutations.
|
To investigate three families and one sporadic case with a recessively inherited ataxic syndrome.</AbstractText>Clinical and genetic studies were performed in six individuals. Southern blotting and real time PCR were used to detect deletions of mtDNA and mutations in the POLG gene were identified using a combination of DHPLC and direct DNA sequencing.</AbstractText>The patients have a distinctive, progressive disorder that starts with episodic symptoms such as migraine-like headache or epilepsy. Ataxia, which is a combination of central and peripheral disease, develops later as does ophthalmoplegia. The commonest form of epilepsy was focal and involved the occipital lobes. Myoclonus was common and patients have a high risk of status epilepticus. MRI typically shows signal changes in the central cerebellum, olivary nuclei, occipital cortex, and thalami. COX negative muscle fibers were found in four of six; in one patient these were rare and in another absent. Multiple mtDNA deletions were identified in all patients, although in two these were not apparent on Southern blotting and real time PCR was required to demonstrate the defect. Two families were homozygous for a previously described POLG mutation, G1399A (A467T). One family and the sporadic case had the same two new mutations, a G to C at position 1491 (Q497H) and a G to C at 2243 (W748S).</AbstractText>Mutations in POLG cause a recessively inherited syndrome with episodic features and progressive ataxia. Characteristic changes on MRI are seen and although skeletal muscle may appear morphologically normal, multiple mtDNA deletions can be detected using real-time PCR.</AbstractText>
|
2,337,825 |
Neurologic features of horizontal gaze palsy and progressive scoliosis with mutations in ROBO3.
|
To review the neurologic, neuroradiologic, and electrophysiologic features of autosomal recessive horizontal gaze palsy and progressive scoliosis (HGPPS), a syndrome caused by mutation of the ROBO3 gene on chromosome 11 and associated with defective decussation of certain brainstem neuronal systems.</AbstractText>The authors examined 11 individuals with HGPPS from five genotyped families with HGPPS. Eight individuals had brain MRI, and six had electrophysiologic studies.</AbstractText>Horizontal gaze palsy was fully penetrant, present at birth, and total or almost total in all affected individuals. Convergence, ocular alignment, congenital nystagmus, and vertical smooth pursuit defects were variable between individuals. All patients developed progressive scoliosis during early childhood. All appropriately studied patients had hypoplasia of the pons and cerebellar peduncles with both anterior and posterior midline clefts of the pons and medulla and electrophysiologic evidence of ipsilateral corticospinal and dorsal column-medial lemniscus tract innervation. Heterozygotes were unaffected.</AbstractText>The major clinical characteristics of horizontal gaze palsy and progressive scoliosis were congenital horizontal gaze palsy and progressive scoliosis with some variability in both ocular motility and degree of scoliosis. The syndrome also includes a distinctive brainstem malformation and defective crossing of some brainstem neuronal pathways.</AbstractText>
|
2,337,826 |
Leigh syndrome associated with mitochondrial complex I deficiency due to a novel mutation in the NDUFS1 gene.
|
Mutations in the nuclear-encoded subunits of complex I of the mitochondrial respiratory chain are a recognized cause of Leigh syndrome (LS). Recently, 6 mutations in the NDUFS1 gene were identified in 3 families.</AbstractText>To describe a Spanish family with LS, complex I deficiency in muscle, and a novel mutation in the NDUFS1 gene.</AbstractText>Using molecular genetic approaches, we identified the underlying molecular defect in a patient with LS with a complex I defect.</AbstractText>The proband was a child who displayed the clinical features of LS.</AbstractText>Muscle biochemistry results showed a complex I defect of the mitochondrial respiratory chain. Sequencing analysis of the mitochondrial DNA-encoded ND genes, the nuclear DNA-encoded NDUFV1, NDUFS1, NDUFS2, NDUFS4, NDUFS6, NDUFS7, NDUFS8, and NDUFAB1 genes, and the complex I assembly factor CIA30 gene revealed a novel homozygous L231V mutation (c.691C-->G) in the NDUFS1 gene. The parents were heterozygous carriers of the L231V mutation.</AbstractText>Identifying nuclear mutations as a cause of respiratory chain disorders will enhance the possibility of prenatal diagnosis and help us understand how molecular defects can lead to complex I deficiency.</AbstractText>
|
2,337,827 |
Founder haplotype for Machado-Joseph disease in the Indian population: novel insights from history and polymorphism studies.
|
The ACA haplotype is associated with 72% of the expanded repeats in Machado-Joseph disease (MJD) worldwide and has been traced to a Portuguese ancestry. It is present in only 5% of the normal chromosomes in the Portuguese population.</AbstractText>To trace the origin of expanded alleles of MJD in the Indian population.</AbstractText>We performed CAG repeat size determination and haplotype analysis for 9 families with MJD and 263 unrelated chromosomes with unexpanded CAG sequences from the Indian population.</AbstractText>All the expanded alleles were exclusively associated with the ACA haplotype in the Indian population. Interestingly, this haplotype was very common in normal alleles (40%) as compared with the Portuguese population (5%) and was significantly associated with large normal alleles (Pearson chi(2)1 = 87.1, P<.001) in the Indian population. We also observed a rare intermediate allele of MJD with the ACA haplotype but with a CAG variant instead of CAA at the sixth position in the repeat tract.</AbstractText>Overrepresentation of the ACA haplotype in large normal alleles in India as compared with the Portuguese population suggests that the expansion-prone large normal alleles with the ACA haplotype may have been introduced in the Portuguese population through admixture with South Asian populations. Detailed haplotype analysis of a CAG variant within the repeat tract in an intermediate allele of MJD suggests a mechanism of gene conversion in the expansion.</AbstractText>
|
2,337,828 |
Sex differences in clinical and genetic determinants of levodopa peak-dose dyskinesias in Parkinson disease: an exploratory study.
|
Several factors, both clinical and genetic, may account for the risk of developing levodopa-induced peak-dose dyskinesias (PDD) in patients with Parkinson disease, but it is unclear how these factors interact for modulating the individual susceptibility for PDD.</AbstractText>To examine clinical and genetic risk factors for determining individual susceptibility of PDD in patients with Parkinson disease.</AbstractText>Cohort study.</AbstractText>Referral center for Parkinson disease in Calabria, southern Italy. Patients Two hundred fifty patients with Parkinson disease were screened for the presence or absence of PDD following a short-term levodopa administration, and 215 subjects were available for further evaluations, including genotypic analysis of the CA dinucleotide short tandem repeat (CAn-STR) polymorphism located in the dopamine receptor D2 gene (DRD2).</AbstractText>One hundred five patients (48.8%) exhibited PDD following short-term levodopa administration, and 110 patients (51.2%) did not. Multivariate logistic regression analysis showed that independent predictors for the occurrence of PDD were female sex, earlier age at onset of Parkinson disease, longer duration of treatment, and higher dose of levodopa. Genetic factors related to the DRD2 CAn-STR polymorphism were not independent predictors for PDD in the total population, but they had a strong protective effect on the appearance of PDD when the multivariate analysis was performed in men (odds ratio, 0.34 [95% confidence interval, 0.14-0.84]). In women, a genetic protective effect on PDD was not evident.</AbstractText>Risk factors for PDD, both clinical and genetic, act in different ways for men and women. Genetic factors related to the DRD2 polymorphic status have a protective effect on PDD development in men but not in women. A female sex-related effect for the risk of PDD may be so strong that it overcomes any protective effect due to genetic factors.</AbstractText>
|
2,337,829 |
Presence of alanine-to-valine substitutions in myofibrillogenesis regulator 1 in paroxysmal nonkinesigenic dyskinesia: confirmation in 2 kindreds.
|
Paroxysmal nonkinesigenic dyskinesia (PNKD) is a rare disorder characterized by attacks of involuntary movements brought on by stress, alcohol, or caffeine, but not by movement. An autosomal dominant form of this disorder was mapped to chromosome 2q33-36, and different missense mutations in exon 1 of the myofibrillogenesis regulator 1 (MR1) gene were identified recently in 2 kindreds.</AbstractText>To describe studies on a new pedigree with PNKD, to explore the possibility of locus heterogeneity, and to further delineate the spectrum of mutations in MR1 in 2 families with PNKD.</AbstractText><AbstractText Label="DESIGN, SETTING, AND PATIENTS" NlmCategory="METHODS">All 10 exons of MR1 were sequenced in DNA from members of 2 pedigrees with autosomal dominant PNKD.</AbstractText>Different missense mutations in exon 1 of MR1 that cosegregate with disease were identified in each multiplex family. These single-nucleotide mutations predicted substitution of valine for alanine in residue 7 in one family and residue 9 in the other. The same mutations were found in the only 2 families previously published. Family history and haplotype analysis make it unlikely that the families with the same mutations are related.</AbstractText>The function of MR1 is unknown, but the 2 mutations identified in the 4 families with PNKD studied to date are predicted to disrupt the amino terminal alpha-helix suggesting that this region of the gene is critical for proper gene function under stressful conditions. Study of additional families will be important to determine whether analysis of a single exon (MR1 exon 1) is sufficient for genetic testing purposes.</AbstractText>
|
2,337,830 |
Restless legs syndrome: confirmation of linkage to chromosome 12q, genetic heterogeneity, and evidence of complexity.
|
Genes are involved in the etiology of restless legs syndrome, a common sensorimotor disorder.</AbstractText>To replicate and to further characterize our previously reported chromosome 12q linkage results.</AbstractText>Family linkage study.</AbstractText>A total of 276 individuals from 19 families have been examined using a selection of markers spanning the identified candidate interval on chromosome 12q.</AbstractText>Two-point analyses of individual pedigrees indicated that 5 kindreds were consistent with linkage to chromosome 12q. When considering these 5 pedigrees along with the family in which linkage was originally reported, we observed a maximum 2-point logarithm-of-odds score of 5.67 (at theta = 0.10; for marker D12S1636; autosomal recessive) and a maximum multipoint logarithm-of-odds score of 8.84 between the interval defined by markers D12S326 and D12S304. Furthermore, our results also suggest the presence of heterogeneity in restless legs syndrome as linkage was formally excluded across the region in 6 pedigrees. Interestingly, significantly higher periodic leg movements during sleep indices were observed for all probands with restless legs syndrome from linked families.</AbstractText>These results support the presence of a major restless legs syndrome-susceptibility locus on chromosome 12q, which has been designated as RLS1, and also suggest that at least one additional locus may be involved in the origin of this prevalent condition.</AbstractText>
|
2,337,831 |
Utilization of BRCA1/BRCA2 mutation testing in newly diagnosed breast cancer patients.
|
Among newly diagnosed breast cancer patients who are at risk for carrying a BRCA1 or BRCA2 mutation, knowledge of mutation status can influence local breast cancer treatment decisions. Thus, genetic testing at the time of diagnosis is increasingly considered an option for such patients. In this study, we evaluated factors associated with the decision to undergo BRCA1/BRCA2 gene testing at the time of initial breast cancer diagnosis.</AbstractText>Participants were newly diagnosed breast cancer patients who had not yet received definitive local breast cancer treatment and who had a family history consistent with hereditary breast cancer. Participants were offered genetic counseling and BRCA1/BRCA2 testing with results in 2 to 3 weeks.</AbstractText>Of 231 patients who referred to the study, 20 (9%) declined the baseline interview, 34 (15%) completed a baseline interview but declined genetic testing, and 177 (76%) underwent BRCA1/BRCA2 testing. Physician recommendation for BRCA1/BRCA2 testing and indecision about definitive local treatment were both associated with undergoing testing. Among patients who were tested, 38 (21%) proceeded with definitive local treatment before receiving test results. Delay in the availability of test results and low levels of anxiety were associated with the decision to proceed with definitive local treatment before receiving test results.</AbstractText>These results suggest that if rapid testing is available and genetic referrals are made for appropriate patients, a high proportion are likely to opt for such testing. In particular, patients who have not yet reached a decision about definitive local treatment may benefit from a genetic referral.</AbstractText>
|
2,337,832 |
Lives to save lives--the ethics of tissue typing.
|
Should we allow tissue typing of in vitro embryos in order to implant those which could provide potentially life-saving cells to an existing serious ill sibling with that tissue type? A case is made that such tissue matching does not involve unacceptable instrumentality towards or commodification of children. The key distinction is that the parents' request for tissue typing is reactive in the face of serious medical need rather than being proactive in the sense of seeking the means to specify a child with chosen desirable characteristics. Nevertheless, as preimplantation genetic diagnosis (PGD) is a relatively new technique, both long-term safety issues concerning effects on child development following embryo biopsy and the risks of misdiagnosis must be given due weight as must the avoidance of exploitation of couples desperate to save a sick child. The HFEA originally made a distinction, recently revoked, between allowing tissue typing after PGD to select against affected embryos and denying it when PGD is not required because the embryos are not at risk of inheriting the disease suffered by the existing sibling. If tissue typing is not inherently unethical and misdiagnosis poses a greater risk than biopsy damage, then this distinction is not ethically tenable.
|
2,337,833 |
Standardization strategy for quantitative PCR in human seminoma and normal testis.
|
Housekeeping genes are commonly used as endogenous references in quantitative RT-PCR. Ideally these genes are constitutionally expressed by all cell types and do not vary under experimental conditions. Tissues of 9 normal testes and 22 classical pure seminoma were obtained for RNA-extraction. Real-time RT-PCR was used to examine the mRNA-expression of ubiquitin C, beta-actin, GAPDH, 18S ribosomal RNA (18S rRNA) and porphobilinogen-deaminase (PBGD). Additionally, 3 normal testicular tissues and 39 seminoma, including 1 normal testis and 17 seminoma of the RT-PCR group, were utilized for microarray analyses. Ubiquitin C (protein degradation) was down-regulated, GAPDH (carbohydrate metabolism), beta-actin (cytoskeleton), 18S rRNA (ribosome) and PBGD (porphyrin metabolism) were up-regulated in seminoma. A normalization of the target gene data with up-regulated housekeeping genes would equalize or underestimate up-regulated data and overestimate down-regulated data. We demonstrate that none of the investigated housekeeping genes is suitable for normalization of the target gene RT-PCR data, but may be essential for tumor metabolism in human seminoma. Further, we developed a standardization strategy, which is applicable to many experimental investigations.
|
2,337,834 |
HLA-matched embryos selected for siblings requiring haematopoietic stem cell transplantation: a psychological perspective.
|
Allogeneic haematopoietic stem cell transplantation (HSCT) is a treatment for a number of acquired and congenital diseases. An important factor in the outcome of the treatment is the degree of human leukocyte antigen (HLA) compatibility between patient and donor. HLA identical siblings therefore provide the best chance for the recipient. Preimplantation genetic diagnosis (PGD) can be used to select HLA identical embryos if there is no HLA compatible sibling in the family. The Centre for Reproductive Medicine considered it morally justified to give medical assistance to couples in need of an HLA matched sibling. Two considerations played an important role in this respect: (i) the use as a donor should not be the only parents' motive for having the child and (ii) IVF and HLA typing on the embryos would be less of a burden for the parents than other alternatives. Since the first request in 2000, 12 couples have been referred for psychological counselling. The motivation of four couples will be discussed in depth. The validity of the arguments will be checked against the experience of the actual cases. The consequences of the treatment on the welfare of the future donor child will be discussed.
|
2,337,835 |
Identification of a cryptic lethal mutation in the mouse t(w73) haplotype.
|
t haplotypes are naturally occurring, variant forms of the t complex on mouse chromosome 17, characterized by the presence of four inversions with respect to wild-type. They harbour mutations causing male sterility, male transmission ratio distortion (TRD) and embryonic lethality. Mice carrying t haplotypes have been found throughout the world, and genetic studies of the lethal mutations have identified at least 16 complementation groups. The embryonic lethal phenotypes of many t haplotypes have been characterized in detail, and are thought to be the consequence of homozygosity for single gene mutations. However, the existence of additional mutations in genes that function at later stages of development would be obscured. Here we investigated the possibility of multiple mutations in t haplotypes by screening the t(w73) haplotype for the presence of novel mutations. Since genetic analysis of t haplotype mutations is hindered by recombination suppression due to the inversions, deletion complexes covering the proximal two-thirds of the t complex were used to uncover the presence of any new lethal alleles. This analysis revealed a novel mutation between D17Jcs41 and D17Mit100, causing mice carrying both t(w73) and selected deletions to die at birth, prior to feeding. The finding of a new, cryptic lethal mutation in t haplotypes is an indication that these recombinationally isolated chromosomes, which already contain at least one lethal mutation that prevents homozygosity, may serve as sinks for the accumulation of additional recessive mutations.
|
2,337,836 |
Genomics, genetic epidemiology, and genomic medicine.
|
Medical science is on the threshold of unparalleled progress as a result of the advent of genomics and related disciplines. Human genomics, the study of structure, function, and interactions of all genes in the human genome, promises to improve the diagnosis, treatment, and prevention of disease. This opportunity is the result of the recent completion of the Human Genome Project. It is anticipated that genomics will bring to physicians a powerful means to discover hereditary elements that interact with environmental factors leading to disease. However, the expected transformation toward genomics-based medicine will occur over decades. It will require efforts of many scientists and physicians to begin now to sort out the vast amounts of information in the human genome and translate it to meaningful applications in clinical practice. Meanwhile, practicing physicians and health professionals need to be trained in the principles, applications, and limitations of genomics and genomic medicine. Only then will we be in a position to benefit patients, which is the ultimate goal of accelerating scientific progress in medicine. In this inaugural article, we introduce and discuss concepts, facts, and methods of genomics and genetic epidemiology that will be drawn on in the forthcoming topics of the clinical genomics series.
|
2,337,837 |
Amphotericin B.
|
Invasive fungal infections are a major cause of morbidity and mortality in immunodeficient individuals (such as AIDS patients) and in transplant recipients or tumor patients undergoing immunosuppressive chemotherapy. Amphotericin B is one of the oldest, yet most efficient antimycotic agents. However, its usefulness is limited due to dose-dependent side-effects, notably nephrotoxicity. In order to improve its safety margin, new pharmaceutical formulations of amphotericin B have been designed especially to reduce its detrimental effects on the kidneys. Since the 1980s, a wide variety of new amphotericin B formulations have been brought forward for clinical testing, many of which were approved and reached market value in the 1990s. This review describes and discusses the molecular genetics, pharmacological, toxicological, and clinical aspects of amphotericin B itself and many of its innovative formulations.
|
2,337,838 |
Evaluation and management of renal tumors in the Birt-Hogg-Dubé syndrome.
|
Herein we describe the evaluation and management of renal tumors in Birt-Hogg-Dubé (BHD), an autosomal dominant disorder predisposing to cutaneous fibrofolliculomas, pulmonary cysts, spontaneous pneumothorax and renal tumors.</AbstractText>A total of 124 affected individuals underwent comprehensive clinical evaluation, including body computerized tomography, to determine cutaneous, pulmonary and renal manifestations of BHD. Of these individuals 14 had their renal tumors managed at our institution.</AbstractText>Of the 124 BHD affected individuals 34 (27%) had renal tumors of various histologies, most commonly hybrid oncocytic tumor and chromophobe renal carcinoma. Average age at renal tumor detection was 50.4 years and multiple tumors were found in a majority of patients. Some patients with renal tumors were identified that did not have the characteristic cutaneous hallmarks of BHD. In 4 of the 14 patients treated at our institution small (less than 3 cm) renal tumors were observed, while 10 others underwent a total of 12 renal procedures, including 4 radical and 8 partial nephrectomies. At a median of 38 months of followup 5 of these 10 patients remained free of disease, 3 had small renal tumors and 2 died of metastatic renal cancer.</AbstractText>Patients with BHD are at risk for multiple renal tumors that are often malignant and can metastasize. Individuals at risk or affected by BHD should be radiographically screened for renal tumors at periodic intervals and they are best treated with nephron sparing surgical approaches. Genetic testing for this syndrome is now available.</AbstractText>
|
2,337,839 |
Bipolar disorder and polymorphisms in the dysbindin gene (DTNBP1).
|
Several studies support the dysbindin (dystrobrevin binding protein 1) gene (DTNBP1) as a susceptibility gene for schizophrenia. We previously reported that variation at a specific 3-locus haplotype influences susceptibility to schizophrenia in a large United Kingdom (UK) Caucasian case-control sample.</AbstractText>Using similar methodology to our schizophrenia study, we have investigated this same 3-locus haplotype in a large, well-characterized bipolar sample (726 Caucasian UK DSM-IV bipolar I patients; 1407 ethnically matched controls).</AbstractText>No significant differences were found in the distribution of the 3-locus haplotype in the full sample. Within the subset of bipolar I cases with predominantly psychotic episodes of mood disturbance (n = 133) we found nominally significant support for association at this haploptype (p < .042) and at SNP rs2619538 (p = .003), with a pattern of findings similar to that in our schizophrenia sample. This finding was not significant after correction for multiple testing.</AbstractText>Our data suggest that variation at the polymorphisms examined does not make a major contribution to susceptibility to bipolar disorder in general. They are consistent with the possibility that DTNBP1 influences susceptibility to a subset of bipolar disorder cases with psychosis. However, our subset sample is small and the hypothesis requires testing in independent, adequately powered samples.</AbstractText>
|
2,337,840 |
Generation of a human embryonic stem cell line encoding the cystic fibrosis mutation deltaF508, using preimplantation genetic diagnosis.
|
Human embryonic stem (hES) cells are pluripotent cells isolated from early human embryos. They can be grown in vitro and made to differentiate into many different cell types. These properties have suggested that they may be useful in cell replacement therapy for many degenerative diseases. However, if hES cells could also be manufactured with mutations significant in human disease, they could provide a powerful in-vitro tool for modelling disease processes and progression in a number of different cell types, as well as providing an ideal system for studying in-vitro toxicity and efficacy of drugs and other therapeutic systems such as gene therapy. Embryos with such mutations are generated as part of routine genetic testing during preimplantation genetic diagnosis, providing the opportunity to generate cell lines with significant mutations. A human embryonic stem cell line homozygous for the most common mutation leading to cystic fibrosis in humans (delta F508) has been generated and characterized. This cell line has the same morphology and expresses proteins typical of other unaffected hES cell lines. This cell line represents an important in-vitro tool for understanding the pathophysiology of cystic fibrosis, and presents exciting opportunities to test the efficacy and toxicity of new therapies relevant to CF.
|
2,337,841 |
Preimplantation genetic diagnosis for aneuploidy screening in repeated implantation failure.
|
Chromosomal abnormalities are thought to be responsible for implantation failure, and among chromosomal abnormalities in normally developing embryos, aneuploidy is the most frequent. Genetic testing of preimplantation embryos for chromosomal aneuploidy allows selection of chromosomally normal embryos, and early detection of chromosomal aberration will increase the chance of conceiving. Preimplantation genetic diagnosis for aneuploidy screening (PGD-AS), performed by polar body or blastomere analysis, is used in infertile patients treated with assisted reproduction technologies, especially in those with a poor prognosis, e.g. repeated IVF failure, advanced maternal age, or recurrent spontaneous abortion. The aim of this paper is to clarify the impact of PGD-AS in repeated implantation failure. In this review, the data collected so far regarding PGD-AS in this patient group will be discussed in depth.
|
2,337,842 |
Clinical application of multiple displacement amplification in preimplantation genetic diagnosis.
|
Multiple displacement amplification (MDA) is a technique used in the amplification of very small amounts of DNA. MDA is reported to yield large quantities of high-quality DNA. The applicability of MDA to single cells was recently demonstrated as a potential technique for preimplantation genetic diagnosis (PGD). This paper shows the first clinical application of MDA in PGD. Two cycles of PGD were performed in two diseases, resulting in two pregnancies. All the diagnoses given on blastomeres were confirmed on the non-transferred whole embryos. The blastomere diagnosis was coupled with short tandem repeat (STR) analysis (16 loci) in all cycles. Allelic drop-out (ADO) assessment and amplification efficiency were evaluated on 40 single lymphocytes derived from parents of each disease. ADO and amplification failure were 10.3 and 2.2% for beta-thalassaemia and 17.9 and 2.2% for cystic fibrosis respectively. HLA matching for A, B and DR was performed successfully on single cell for the beta-thalassaemia family using similar methods to genomic DNA. The PGD protocol used in all diseases consists of MDA amplification, followed by a standard polymerase chain reaction protocol. Although HLA matching was not applied to embryos, its feasibility was shown on single cell DNA amplified by MDA. Altogether, these data show the simplicity and reliability of performing PGD in combination with HLA matching and STR analysis using MDA.
|
2,337,843 |
Ethical consideration of intentioned preimplantation genetic diagnosis to enable future tissue transplantation.
|
Recently, a case was presented where a couple with one normal child requested preimplantation genetic diagnosis (PGD) with human leukocyte antigen (HLA) typing in order to conceive children who could serve as mutual donors for future transplantations if needed. While PGD for medical reasons is well defined and accepted, application for non-medical conditions is less obvious and still in debate. The present case calls to further extend the indications for PGD and raises a moral question as to whether to allow such intentioned treatment. Although it seems that all siblings might benefit from the procedure, when weighing the risks benefits and the ethical issues included in performing intentioned PGD, it seems that the procedure harbours risks and ethical issues that outweigh the benefit it offers. Therefore, it is time to constrain the slippery slope and state that intentioned PGD for conceiving children who might serve as siblings for mutual tissue donations should be declined.
|
2,337,844 |
Eugenics: some lessons from the past.
|
Eugenics was first debated by the ancient Greeks, particularly Plato and Aristotle, developed in the nineteenth century by Francis Galton and Charles Darwin, and then abused in the twentieth century by right-wing politicians. With the new methods of assisted conception combined with the use of genetic markers, all the old problems of eugenics have resurfaced. Gender selection, embryo selection, preimplantation genetic diagnosis of common disease, and gene replacement techniques (somatic cells) have added greatly to the power of the modern eugenicist. How are these procedures to be monitored and regulated? What is the role of the State compared with individual families for the implementation of the new methodologies? Some of these issues will be discussed.
|
2,337,845 |
Designing babies: what the future holds.
|
Advances in reproductive technology have opened new opportunities to avoid inherited diseases in offspring. The preimplantation genetic diagnosis (PGD) of human embryos permits those embryos carrying gene disorders or a non-diploid chromosome constitution to be identified. Numerous disease genes including those with a late onset have been identified and the conditions averted in children. Risks of abortion have been reduced, and the incidence of live births raised after PGD. It is also possible to select embryos with human leukocyte antigens (HLA) identical to those of a sick elder sibling, and then use stem cells from cord blood at birth to supply the necessary therapy. This form of treatment has alleviated the inherited disease in many recipients. The outlook and ethics of this approach to the alleviation of human disorders are discussed.
|
2,337,846 |
Power and sample size calculations in the presence of phenotype errors for case/control genetic association studies.
|
Phenotype error causes reduction in power to detect genetic association. We present a quantification of phenotype error, also known as diagnostic error, on power and sample size calculations for case-control genetic association studies between a marker locus and a disease phenotype. We consider the classic Pearson chi-square test for independence as our test of genetic association. To determine asymptotic power analytically, we compute the distribution's non-centrality parameter, which is a function of the case and control sample sizes, genotype frequencies, disease prevalence, and phenotype misclassification probabilities. We derive the non-centrality parameter in the presence of phenotype errors and equivalent formulas for misclassification cost (the percentage increase in minimum sample size needed to maintain constant asymptotic power at a fixed significance level for each percentage increase in a given misclassification parameter). We use a linear Taylor Series approximation for the cost of phenotype misclassification to determine lower bounds for the relative costs of misclassifying a true affected (respectively, unaffected) as a control (respectively, case). Power is verified by computer simulation.</AbstractText>Our major findings are that: (i) the median absolute difference between analytic power with our method and simulation power was 0.001 and the absolute difference was no larger than 0.011; (ii) as the disease prevalence approaches 0, the cost of misclassifying a unaffected as a case becomes infinitely large while the cost of misclassifying an affected as a control approaches 0.</AbstractText>Our work enables researchers to specifically quantify power loss and minimum sample size requirements in the presence of phenotype errors, thereby allowing for more realistic study design. For most diseases of current interest, verifying that cases are correctly classified is of paramount importance.</AbstractText>
|
2,337,847 |
Presence of RHD in serologically D-, C/E+ individuals: a European multicenter study.
|
RHD blood group alleles with reduced or absent antigen expression are a clinically significant and heterogeneous group.</AbstractText>To detail population genetics data on apparently D- individuals in central Europe, a six-center study was performed with participants from Austria, Germany, Slovenia, Switzerland, and Russia. A total of 1700 serologically D- samples, positive for C and/or E, were investigated.</AbstractText>Observed unexpressed RHD alleles were 59 RHD-CE-D+ hybrid alleles, 9 apparently regular RHD, 1 new RHD(Y401X); DELs were 8 RHD(M295I), 6 RHD(IVS3+1G>A), and 1 new RHD(X418L); and weakly expressed RHDs were 2 weak D type 5, 1 weak D type 1, 1 RHD category VI type 1, and 1 novel weak D type 26. Although weak D type 26 was shown to have one of the lowest D antigen densities ever observed, it gave rise to anti-D immunization in a transfused D- individual.</AbstractText>The relative occurrence of RHD among serologically D- samples, positive for C and/or E, differed significantly in the investigated central European regions. Considering the growing use of molecular typing techniques, correct identification of blood group alleles with scarce or missing antigen expression is of utmost clinical importance and requires reliable population-based frequency data.</AbstractText>
|
2,337,848 |
Family history as a co-factor for adenocarcinoma and squamous cell carcinoma of the uterine cervix: results from two studies conducted in Costa Rica and the United States.
|
Previous work suggests that cervical cancer may aggregate in families. We evaluated the association between a family history of gynecological tumors and risk of squamous cell and adenocarcinomas of the cervix in 2 studies conducted in Costa Rica and the United States. The Costa Rican study consisted of 2,073 women (85 diagnosed with CIN3 or cancer, 55 diagnosed with CIN2 and 1,933 controls) selected from a population-based study of 10,049 women. The U.S. study consisted of 570 women (124 with in situ or invasive adenocarcinomas, 139 with in situ or invasive squamous cell carcinomas of the cervix and 307 community-based controls) recruited as part of a multicentric case-control study in the eastern part of the United States. Information on family history of cervical and other cancers among first-degree relatives was ascertained via questionnaire. Information on other risk factors for cervical cancer was obtained via questionnaire. Human papillomavirus (HPV) exposure was assessed in both studies using broad spectrum HPV L1-based PCR testing of exfoliated cervicovaginal cells and in Costa Rica by additional testing of plasma collected from participants for antibodies against the L1 protein of HPV types 16, 18, 31 and 45 by ELISA. A family history of cervical cancer in a first-degree relative was associated with increased risk of squamous tumors in both studies (odds ration [OR] = 3.2 for CIN3/cancer vs. controls; 95% confidence interval [CI] = 1.1-9.4 in Costa Rica; OR = 2.6 for in situ/invasive squamous cell carcinoma cases vs. controls, 95% CI = 1.1-6.4 in the Eastern United States study). These associations were evident regardless of whether the affected relative was a mother, sister or daughter of the study participant. Furthermore, observed effects were not strongly modified by age. In Costa Rica, the effect persisted in analysis restricted to HPV-exposed individuals (OR = 3.0; 95% CI = 1.0-9.0), whereas in the Eastern United States study there was evidence of attenuation of risk in analysis of squamous carcinoma cases restricted to HPV positive women (OR = 1.4; 95% CI = 0.29-6.6). No significant association was observed between a family history of cervical cancer in a first-degree relative and adenocarcinomas (OR = 1.3; 95% CI = 0.43-3.9). History of gynecological tumors other than cervical cancer in a first-degree relative was not significantly associated with risk of disease in either study. These results are consistent with a role of host factors in the pathogenesis of squamous cell cervical cancer, although familial aggregation due to shared environmental exposures cannot be ruled out.
|
2,337,849 |
NPHS2 (Podocin) mutations in nephrotic syndrome. Clinical spectrum and fine mechanisms.
|
Nephrotic syndrome (NS) is the most frequent cause of proteinuria in children and is emerging as a leading cause of uremia. Molecular studies in families with recessive NS have led to the discovery of specialized molecules endowed in podocytes that play a role in proteinuria. This review focalizes the key position of podocin (NPHS2 gene) in this rapidly evolving field and furnishes a compendium to those involved in clinics and genetics of NS. Screening for NPHS2 mutations have been done in sporadic NS and familial cases with recessive inheritance, documenting a mutation detection rate of 45-55% in families and 8-20% in sporadic NS according to the different groups and considering all the clinical phenotypes. Almost 50 NPHS2 mutations have been reported and variants and/or non silent polymorphisms potentially involved in proteinuria were recognized. Personalized data on clinical aspects related to responsiveness to drugs, evolution to end stage renal failure and post-transplant outcome are reported. Functional studies and cell sorting experiments demonstrated retention in the endoplasmic reticulum of most mutants involving the stomatin domain. Pull-down experiments with the common R229Q polymorphism demonstrated an altered interaction with nephrin that affects the stability of the functional unit. Overall, data are here presented that underscore a major role of inherited defects of NPHS2 in NS in children (including a relevant impact in sporadic cases) and give the functional rationale for the association. A practical compendium is also given to clinicians involved in the management of NS that should modify the classic therapeutic approach.
|
2,337,850 |
Membranes, ions, and clocks: testing the Njus-Sulzman-Hastings model of the circadian oscillator.
|
Current circadian clock models based on interlocking autoregulatory transcriptional?translational negative feedback loops have arisen out of an explosion of molecular genetic data obtained over the last decade (for review, see Stanewsky, 2003; Young and Kay, 2001). An earlier model of circadian oscillation was based on feedback interactions between membrane ion transport systems and ion concentration gradients (Njus et al., 1974, 1976). This membrane model was posited as a more plausible alternative at the time to the even earlier "chronon" model, which was based on autoregulatory genetic feedback loops (Ehret and Trucco, 1967). The membrane model has been tested in a number of experimental systems by pharmacologically manipulating either ionic gradients across the plasma membrane or ion transport systems, but with inconsistent results. In the meantime, the scope and explanatory power of the genetic models overshadowed inquiries into the role of membrane ion fluxes in clock function. However, several recently developed techniques described in this article have provided a new glimpse into the essential role that membrane ion fluxes play in the mechanism of the core circadian oscillator and indicate that a complete understanding of the clock must include both genetic and membrane-based feedback loops.
|
2,337,851 |
Forward genetic screens to identify circadian rhythm mutants in mice.
|
This article describes the methods and techniques used to produce mutagenized mice to conduct high-throughput forward genetic screens for circadian rhythm mutants in the mouse. In particular, we outline methods to safely prepare and administer the chemical mutagen N-nitroso-N-ethylurea (ENU) to mice. We also discuss the importance of selecting mouse strain and outline breeding strategies, logistics, and throughput to produce these mutant mice. Finally, we discuss the breeding strategies that we use to confirm mutation heritability.
|
2,337,852 |
Circadian genetics in the model higher plant, Arabidopsis thaliana.
|
In recent decades, most research on the circadian rhythms of higher plants has been driven by molecular genetics. A wide variety of experimental approaches have discovered mutants in the plant circadian clock, yet the screens are far from saturated and there must still be important clock-related genes to identify. Direct methods to screen for circadian mutants include the original assay of rhythmic luminescence from promoter:luciferase constructs in planta or a recently developed assay based on stomatal rhythms. Mutants found through simpler screens of processes only partially controlled by the clock are still identifying novel and interesting circadian phenotypes when their rhythms are tested, while the sequenced genome and the large range of mutant stocks available have made reverse genetics increasingly powerful.
|
2,337,853 |
Protistan diversity estimates based on 18S rDNA from seawater incubations in the Western North Atlantic.
|
Cloning/sequencing and fragment analysis of ribosomal RNA genes (rDNA) are becoming increasingly common methods for the identification of microbial taxa. Sequences of these genes provide many additional taxonomic characters for species that otherwise have few distinctive morphological features, or that require involved microscopy or laboratory culture and testing. These same approaches are now being applied with great success in ecological studies of natural communities of microorganisms. Extensive information on the composition of natural microbial assemblages is being amassed at a rapid pace through genetic analyses of environmental samples and comparison of the resulting genetic information with well-established (and rapidly growing) public databases. We examined microbial eukaryote diversity in a natural seawater sample from the coastal western North Atlantic Ocean using two molecular biological approaches: the cloning and sequencing of rRNA genes and by fragment analysis of these genes using the terminal restriction fragment length polymorphism (T-RFLP) method. A simple experiment was carried out to examine changes in the overall eukaryote (largely protistan) diversity and species composition (phylotype diversity) of a natural microbial assemblage when a seawater sample is placed in a container and incubated at ambient light and temperature for 72 h. Containment of the natural seawater sample resulted in relatively minor changes in the overall eukaryote diversity (species richness) obtained by either molecular method at three time points (time-zero, time-24 h, time-72 h). However, substantial changes in the dominance of particular eukaryote phylotypes took place between the three sampling times. Only 18% of the total number of phylotypes observed in the study were observed at all three time points, while 65% (108 of 165) phylotypes were observed only at a single time point (54 unique phylotypes initially, 37 more unique phylotypes at 24 h, and 17 more at 72 h). The results of this study indicate that a high diversity of protistan taxa existed in the original seawater sample at very low abundance, and thus were not observed in the initial characterization of community structure. Containment resulted in significant shifts in the dominance of these taxa, enabling the presence of previously unobserved phylotypes to be documented after 24 or 72 h of incubation.
|
2,337,854 |
Genetic malformations of the cerebral cortex and epilepsy.
|
We reviewed the epileptogenic cortical malformations for which a causative gene has been cloned or a linkage obtained. X-linked bilateral periventricular nodular heterotopia (BPNH) consists of typical BPNH with epilepsy in female patients and prenatal lethality in most males. About 90% of patients have focal epilepsy. Filamin A mutations have been reported in all families and in approximately 20% of sporadic patients. A rare recessive form of BPNH also has been reported. Most cases of lissencephaly-pachygyria are caused by mutations of LIS1 and XLIS genes. LIS1 mutations cause a more severe malformation posteriorly. Most children have isolated lissencephaly, with severe developmental delay and infantile spasms, but milder phenotypes have been recorded. XLIS usually causes anteriorly predominant lissencephaly in male patients and subcortical band heterotopia (SBH) in female patients. Thickness of the band and severity of pachygyria correlate with the likelihood of developing Lennox-Gastaut syndrome. Mutations of the coding region of XLIS are found in all reported pedigrees and in 50% of sporadic female patients with SBH. Autosomal recessive lissencephaly with cerebellar hypoplasia; accompanied by severe delay, hypotonia, and seizures, has been associated with mutations of the RELN gene. Schizencephaly has a wide anatomoclinical spectrum, including focal epilepsy in most patients. Familial occurrence is rare. Initial reports of heterozygous mutations in the EMX2 gene need confirmation. Among several syndromes featuring polymicrogyria, bilateral perisylvian polymicrogyria shows genetic heterogeneity, including linkage to Xq28 in some pedigrees, autosomal recessive inheritance in others, and association with 22q11.2 deletion in some patients. About 65% of patients have severe epilepsy, often Lennox-Gastaut syndrome. Recessive bilateral frontal polymicrogyria has been linked to chromosome 16q12.2-21.
|
2,337,855 |
Hereditary hemochromatosis: population screening based on phenotype in Brazilian blood donors.
|
A population of blood donors was screened for hereditary hemochromatosis (HH) based on the phenotype strategy in accordance with the European consensus.</AbstractText>Nonfasting serum samples were obtained from 1,050 donors. Transferrin saturation (TS) was measured using a threshold of 45%. Donors with a TS > or = 45% were retested in a fasting sample. If TS was elevated, the participants were tested for iron overload by ferritin measurement followed by genetic testing. All donors underwent clinical and laboratory workup for expression of the disease.</AbstractText>A total of 775 (74.6%) of the donors were men, 749 (72.1%) white, and had a mean age of 30 years (range, 8-60 years). Mean +/- SD TS was 25.9% +/- 13.1% (range, 2.1%-85.8%), and there were 58 (5.6%) donors with a TS > or = 45%. Fifty-four subjects had a repeat TS in a fasting serum sample with a mean +/- SD TS of 32.1% +/-16.1% (range, 15.4%-63.0%), and 12 donors had a TS > or = 45%. Ten complied with genetic testing and ferritin measurement. The study found four donors with HH-related mutations (C282Y and/or H63D); therefore, a gene allele frequency of 0.4%. Only the C282Y homozygote had diagnostic criteria for HH, defining a disease frequency of 0.1%. None of the donors who were mutations carriers had clinical or laboratory manifestations of organic injury.</AbstractText>We conclude that this is a feasible screening strategy that, by timely diagnosing HH, allows patients not only to benefit from effective treatment but also to have disease progression halted.</AbstractText>
|
2,337,856 |
A comprehensive literature review of haplotyping software and methods for use with unrelated individuals.
|
Interest in the assignment and frequency analysis of haplotypes in samples of unrelated individuals has increased immeasurably as a result of the emphasis placed on haplotype analyses by, for example, the International HapMap Project and related initiatives. Although there are many available computer programs for haplotype analysis applicable to samples of unrelated individuals, many of these programs have limitations and/or very specific uses. In this paper, the key features of available haplotype analysis software for use with unrelated individuals, as well as pooled DNA samples from unrelated individuals, are summarised. Programs for haplotype analysis were identified through keyword searches on PUBMED and various internet search engines, a review of citations from retrieved papers and personal communications, up to June 2004. Priority was given to functioning computer programs, rather than theoretical models and methods. The available software was considered in light of a number of factors: the algorithm(s) used, algorithm accuracy, assumptions, the accommodation of genotyping error, implementation of hypothesis testing, handling of missing data, software characteristics and web-based implementations. Review papers comparing specific methods and programs are also summarised. Forty-six haplotyping programs were identified and reviewed. The programs were divided into two groups: those designed for individual genotype data (a total of 43 programs) and those designed for use with pooled DNA samples (a total of three programs). The accuracy of programs using various criteria are assessed and the programs are categorised and discussed in light of: algorithm and method, accuracy, assumptions, genotyping error, hypothesis testing, missing data, software characteristics and web implementation. Many available programs have limitations (eg some cannot accommodate missing data) and/or are designed with specific tasks in mind (eg estimating haplotype frequencies rather than assigning most likely haplotypes to individuals). It is concluded that the selection of an appropriate haplotyping program for analysis purposes should be guided by what is known about the accuracy of estimation, as well as by the limitations and assumptions built into a program.
|
2,337,857 |
Genetic structure in the coral-reef-associated Banggai cardinalfish, Pterapogon kauderni.
|
In this study, we used 11 polymorphic microsatellite loci to show that oceanic distances as small as 2-5 km are sufficient to produce high levels of population genetic structure (multilocus F(ST) as high as 0.22) in the Banggai cardinalfish (Pterapogon kauderni), a heavily exploited reef fish lacking a pelagic larval dispersal phase. Global F(ST) among all populations, separated by a maximum distance of 203 km, was 0.18 (R(ST) = 0.35). Moreover, two lines of evidence suggest that estimates of F(ST) may actually underestimate the true level of genetic structure. First, within-locus F(ST) values were consistently close to the theoretical maximum set by the average within-population heterozygosity. Second, the allele size permutation test showed that R(ST) values were significantly larger than F(ST) values, indicating that populations have been isolated long enough for mutation to have played a role in generating allelic variation among populations. The high level of microspatial structure observed in this marine fish indicates that life history traits such as lack of pelagic larval phase and a good homing ability do indeed play a role in shaping population genetic structure in the marine realm.
|
2,337,858 |
Disclosing genetic test results to family members.
|
To describe the experiences of disclosing genetic test results to biological family members among people tested for Huntington's disease (HD) or hereditary breast and ovarian cancer (HBOC).</AbstractText>Grounded theory methodology.</AbstractText>Open-ended, tape-recorded interviews were conducted with 29 participants-24 who had received genetic test results and 5 who had decided not to be tested. The participants were from three countries, including 15 U.S. states. Interviews occurred from 2 months to 4 years after receiving test results. Tapes were transcribed and analyzed for conceptual categories to describe the experience of disclosing genetic test results.</AbstractText>Participants described the effects and meaning of disclosing test results to their various family members, and they selectively disclosed results to family members. The timing of disclosure was influenced by the particular disease and the person's perceived need to prepare. Disclosure of genetic test results brought the risk of HD and HBOC to the foreground, not only for the person tested but for family members as well.</AbstractText>This study elucidated the perspective of the "discloser" and the consequences they anticipated and experienced.</AbstractText>
|
2,337,859 |
Grape anaphylaxis: a study of 11 adult onset cases.
|
Reports of immunoglobulin E (IgE)-mediated allergic reactions to grapes and wine are limited in the literature. Nevertheless, grapes are widely grown and consumed in Mediterranean countries. The object of this prospective study was to present clinical features, in vivo and in vitro allergy testing, and human leukocyte antigen (HLA) serotyping in patients with recurring reactions to grapes and grape products. Eleven unrelated Greek patients, six men and five women (aged 16-44 years; mean, 26.9 years) were enrolled based on a documented history of IgE-mediated reactions to grapes, wine, or other grape products. Their evaluation included full history, reaction severity, clinical examination, skin-prick tests with food allergens and molds, serum IgE, specific IgEs to the same allergen battery, and HLA typing. Patients reported 35 grape-induced anaphylaxis episodes ranging from moderate (more than one system involved but not prominent respiratory or cardiovascular symptoms; 45.5%) to severe (serious respiratory obstruction and/or hypotension and loss of consciousness; 54.5%). A causative agent was identified: wine, 10/35 (28.6%); red grapes, 9/35 (25.7%); stuffed vine leaves, 8/35 (22.9%); raisins, 3/35 (8.6%); white grapes, 2/35 (5.7%); wine vinegar, 2/35 (5. 7%); and grape juice, 1/35 (2.9%). Other foods that induced anaphylaxis were apples (54.5%), cherries (18.6%), peaches (18.6%), and bananas (9.3%). Specific IgE values were in accordance with skin-prick tests reactivity. Concerning HLA typing, 9/11 possessed HLA-DR11(5) and -DQ7(3) and the remaining two possessed HLA-DR17(3) and -DQ2 antigens. Grapes, wine and other grape products might cause serious allergic reactions in sensitized individuals. The cosensitization and reaction incidence to other fruit allergens could be a basis for further investigation of panallergens of fruits. HLA class II antigens may contribute in genetic predisposition to these allergic reactions.
|
2,337,860 |
Ethics and research assessing the relative roles of genes and the environment.
|
Research on the interaction of genes and the environment is revealing that many human diseases have both genetic and environmental components. Even traditional "environmental" diseases, such as infections, appear to interact with genetic components in the human host. Environmental genetics research will inevitably increase understanding of individual susceptibilities to toxic exposures in the environment and harmful side effects of medications; therefore, it has great promise for improving the prevention and treatment of human diseases. However, realizing the benefits of this research requires careful attention to ethical issues that are particularly relevant in this context. This article reviews some of the most pressing issues related to research design and methods, as well as from the application of research results (e.g., workplace genetic screening and legal toxic torts, personal medical responsibility, and the relationship between genetics and public health measures).
|
2,337,861 |
Multiplex reverse transcription-polymerase chain reaction combined with on-chip electrophoresis as a rapid screening tool for candidate gene sets.
|
Combining multiplex reverse transcription-polymerase chain reaction (mRT-PCR) with microfluidic amplicon analysis, we developed an assay for the rapid and reliable semiquantitative expression screening of 11 candidate genes for drug resistance in human malignant melanoma. The functionality of this approach was demonstrated by low interexperimental variations of amplicon quantities after endpoint analysis. When applied to RNA samples derived from drug-sensitive and -resistant melanoma cell lines, mRT-PCR delivered results qualitatively concordant with data obtained from Northern blot and array analyses. The screening of additional melanoma cell lines resulted in distinct expression patterns for ten candidate genes. Our approach reveals a rapid and easy-to-handle alternative for candidate gene set evaluation from limited amounts of RNA.
|
2,337,862 |
Hematopoietic transplantation for bone marrow failure syndromes and thalassemia.
|
Several genetic diseases, generally considered as congenital diseases, are characterized by bone marrow failure during early childhood. Hematopoietic stem cell transplantation is the only curative treatment for syndromes involving bone marrow failure and thalassemia. In this slate-of-the-art review, we wish to focus on the results of hematopoietic transplantation in treating some of these diseases, with a special emphasis on congenital bone marrow failure and thalassemia. The results of this procedure have improved over the previous years, mainly when performed by experienced teams. New conditioning regimes based on fludarabine and the use of HLA-identical donors have been related with better survivals. In the previous years, donors other than HLA-identical siblings have been increasingly used in patients not responding to conventional measures, but this approach needs to be evaluated in larger studies.
|
2,337,863 |
Primary adrenal insufficiency in children: twenty years experience at the Sainte-Justine Hospital, Montreal.
|
Primary adrenal insufficiency (PAI) in the pediatric population (0-18 yr) is most commonly attributed to congenital adrenal hyperplasia (CAH), which occurs in about 1 in 15,000 births, followed by Addison's disease, with an assumed autoimmune etiology. However, molecular advances have increased the number of possible diagnoses. The objective of this study was to determine the incidence and etiologies of PAI in our pediatric population. All patients with a diagnosis of PAI followed by the Endocrinology Service at our institution between September 1981 and September 2001 were studied. One hundred three patients (48 boys) were identified, primarily by the Endocrinology Clinic case registry. CAH was the most frequent etiology (71.8%). However, non-CAH etiologies accounted for 28.2%, of which 55% were nonautoimmune in etiology. Importantly, the CAH sex ratio was 1:1, despite the absence of biochemical screening for this condition in Quebec newborns. Patients with autoimmune polyendocrinopathy-candidiasis-ectodermal dysplasia (APECED) developed adrenal insufficiency 4 yr earlier than those with non-autoimmune disease. Finally, we review the rare etiologies of PAI and propose an algorithm to aid in targeted genetic testing.
|
2,337,864 |
Maternal hormones as a tool to adjust offspring phenotype in avian species.
|
Avian eggs contain substantial amounts of maternal hormones and so provide an excellent model to study hormone-mediated maternal effects. We review this new and rapidly evolving field, taking an ecological and evolutionary approach and focusing on effects and function of maternal androgens in offspring development. Manipulation of yolk levels of androgens within the physiological range indicates that maternal androgens affect behaviour, growth, morphology, immune function and survival of the offspring, in some cases even long after fledging. Descriptive and experimental studies show systematic variation in maternal androgen deposition both within and among clutches, as well as in relation to the sex of the embryo. We discuss the potential adaptive value of maternal androgen transfer at all these three levels. We conclude that maternal androgen deposition in avian eggs provides a flexible mechanism of non-genetic inheritance, by which the mother can favour some offspring over others, and adjust their developmental trajectories to prevailing environmental conditions, producing different phenotypes. However, the literature is less consistent than often assumed and at all three levels, the functional explanations need further experimental testing. The field would greatly benefit from an analysis of the underlying physiological mechanisms.
|
2,337,865 |
Reproductive decision making before and after predictive testing for Huntington's disease: an Australian perspective.
|
A retrospective study examined both pre- and post-result reproductive decision making for 281 people at risk for Huntington's disease aged 18-45 years who had undergone predictive testing in one centre in Australia between 1990 and 2002. Forty-eight per cent of subjects had one or more pre-result pregnancies, and of these, three had prenatal linkage testing. One high-risk (50%) pregnancy was terminated. Four couples chose an alternative reproductive option. Following testing, data were available for 231 subjects, and no significant difference was found between mutation carriers and non-carriers in the occurrence of post-result pregnancies. This contrasts with the finding of a recent European study, although the outcome of the present study may have been influenced by loss of follow-up data for 50 subjects. Five carriers (17%) had a total of six prenatal tests. Four showed a carrier result and these pregnancies were terminated. Two carriers utilized an alternative reproductive option (donor insemination and pre-implantation genetic diagnosis). The results of this study confirm previous findings of a low uptake of prenatal testing and alternative reproductive options by people at risk for Huntington's disease undergoing predictive testing.
|
2,337,866 |
A framework for genetic service provision for haemophilia and other inherited bleeding disorders.
|
This framework document offers guidance to patients, doctors, nurses, laboratory scientists, funders and hospitals on the provision of clinical and laboratory genetic services for haemophilia. With recent advances in molecular laboratory techniques it is now possible to give the vast majority of individual patients and family members very reliable genetic information. To enable these genetic data to be used for both the optimal treatment of patients with inherited bleeding disorders and for appropriate reproductive decisions in carriers, there needs to be a clear and robust framework for systematically acquiring the necessary clinical, personal, family and laboratory information upon which decisions can be made. This document provides guidance on the range and standards of clinical and laboratory genetic services which should be offered to patients and their families. Included are arrangements for genetic counselling and testing (including consent and confidentially issues), management of early pregnancy, standards for laboratory genetic services, as well as advice on data storage, security and retrieval.
|
2,337,867 |
Utility of a (GT) dinucleotide repeat in intron 1 of the factor 8 gene for haemophilia A carrier diagnosis.
|
We report the usefulness of a dinucleotide GT repeat in intron 1 of the factor 8 gene in carrier diagnosis of haemophilia A (HA). We analyzed 47 women from HA families in which the mutation was not identified in the index case and in which the common intragenic polymorphic markers were uninformative. The intron 1 GT repeat was useful to identify the X chromosome with the mutation in 19 of them. The analysis of this easily detectable marker in conjunction with other current markers may facilitate X chromosome identification in a large proportion of HA families.
|
2,337,868 |
[Modeling effect of homo- or heterozygosity on animal growth intensity].
|
A model has been developed that describes the dependence of a quantitative selective trait on the animal homo- and heterozygosity for the genes that control the biochemical reaction rate (isoenzyme systems). The model includes any cases of gene control of a quantitative trait and is applicable to real, genetically heterogeneous populations. The results of testing the model show that it can be used for identifying the genes involved in additive polygenic determination of quantitative commercially valuable traits.
|
2,337,869 |
The ethics of pharmacogenomics.
|
Of the future technologies arising from the Human Genome Project, pharmacogenomics will probably be the first to have a widespread impact on the everyday practice of medicine. This technology offers great benefits but also presents some difficult ethical challenges. This paper explains what pharmacogenomics is and examines three of the issues that it raises: orphan populations, the use of ethnicity in drug trials, and potential obstacles to informed consent for genetic testing.
|
2,337,870 |
Subtelomere deletions and translocations are frequently familial.
|
In recent years, strategies have been developed to investigate the possible role of chromosomal subtelomere regions in genetic disorders. The present study was to determine the incidence of familial subtelomeric abnormalities among individuals with developmental delay, idiopathic mental retardation, or non-specific congenital abnormalities. A review was conducted for patients and their relatives on whom subtelomeric DNA fluorescence in situ hybridization (telo-FISH) studies were performed. Patients were identified through a search of the Mayo Genetics System (MGS) database. Of 2,170 consecutive telo-FISH index case studies completed in our laboratory between January 2002 and December 2003, 121 or 5.6% had abnormalities of the subtelomere region. The present report includes 18 other abnormal index cases seen prior to 2002 to yield a total of 139 abnormal index cases. This represents 71 index patients with deletions, 53 index patients with derivative chromosomes, and 15 index patients with balanced rearrangements. A familial abnormality was identified in 29 (51.8%) of 56 families in whom parents and/or sibs were available for testing. Among 28 patients with deletions, 9 (32%) had an inherited deletion, whereas 19 (68%) were de novo. Family members of 20 index patients with derivative chromosomes were tested. Of these, 13 (65%) patients inherited the abnormality from a parent (12 from a parent who had a balanced translocation and 1 from a parent with the same abnormality), while 7 (35%) apparently arose de novo. Seven (88%) of 8 with balanced translocations inherited the translocation from one parent. The most common familial abnormalities involved 8pter deletion or rearrangement. The incidence of familial subtelomeric abnormalities is significantly high making parental telo-FISH studies an essential part of the investigation of patients with subtelomeric chromosome abnormalities.
|
2,337,871 |
Physician exposure to and attitudes toward advertisements for genetic tests for inherited cancer susceptibility.
|
Commercial marketing materials may serve as a source of information for physicians about genetic testing for inherited cancer susceptibility (GTICS) in addition to medical guidelines, continuing education, and journal articles. The primary purposes of this study were to: (1) determine the percentage of physicians who received advertisements for GTICS early in the diffusion of commercial GTICS (1999-2000); (2) assess associated characteristics; and (3) measure the perceived importance of commercial advertisements and promotions in physicians' decisions to recommend testing to patients. A nationally representative, stratified random sample of 1,251 physicians from the American Medical Association (AMA) Physician Masterfile completed a 15-20 min mixed mode questionnaire that assessed specialty, previous use of genetic tests, practice characteristics, age, and receipt of advertising materials (response rate = 71%). Overall, 27.4% (n = 426) had received advertisements. In multivariate analysis, factors associated with receipt of advertisements included: specialties in obstetrics/gynecology, oncology, or gastroenterology; past GTICS use, and age 50+. One of four felt that advertisements would be important in their decision to recommend GTICS. Study results indicate that physicians, particularly in oncology, obstetrics/gynecology, and gastroenterology, began receiving GTICS advertisements commensurate with the early diffusion of commercially available tests into clinical practice. At that time, one-quarter of the physicians considered advertisements to play an important role in their clinical decision making, suggesting attention to other sources of information and additional factors.
|
2,337,872 |
Association of the dopamine transporter (DAT1) 10/10-repeat genotype with ADHD symptoms and response inhibition in a general population sample.
|
Association between attention-deficit hyperactivity disorder (ADHD) and the 10-repeat allele of the dopamine transporter gene (DAT1) has been reported in independent clinical samples using a categorical clinical definition of ADHD. The present study adopts a quantitative trait loci (QTL) approach to examine the association between DAT1 and a continuous measure of ADHD behaviours in a general-population sample, as well as to explore whether there is an independent association between DAT1 and performance on neuropsychological tests of attention, response inhibition, and working memory. From an epidemiological sample of 872 boys aged 6-11 years, we recruited 58 boys scoring above the 90th percentile for teacher reported ADHD symptoms (SWAN ADHD scale) and 68 boys scoring below 10th percentile for genotyping and neuropsychological testing. A significant association was found between the DAT1 homozygous 10/10-repeat genotype and high-scoring boys (chi(2)square=4.6, P<0.03; odds ratio=2.4, 95% CI 1.1-5.0). Using hierarchical linear regression, a significant independent association was found between the DAT1 10/10-repeat genotype and measures of selective attention and response inhibition after adjusting for age, IQ, and ADHD symptoms. There was no association between DAT1 and any component of working memory. Furthermore, performance on tasks of selective attention although associated with DAT1 was not associated with SWAN ADHD high scores after controlling for age and IQ. In contrast, impairment on tasks that tapped sustained attention and the central executive component of working memory were found in high-scoring boys after adjusting for age and IQ. The results suggest that DAT1 is a QTL for continuously distributed ADHD behaviours in the general population and the cognitive endophenotype of response inhibition.
|
2,337,873 |
Epigenetic reprogramming in mammals.
|
Epigenetic marking systems confer stability of gene expression during mammalian development. Genome-wide epigenetic reprogramming occurs at stages when developmental potency of cells changes. At fertilization, the paternal genome exchanges protamines for histones, undergoes DNA demethylation, and acquires histone modifications, whereas the maternal genome appears epigenetically more static. During preimplantation development, there is passive DNA demethylation and further reorganization of histone modifications. In blastocysts, embryonic and extraembryonic lineages first show different epigenetic marks. This epigenetic reprogramming is likely to be needed for totipotency, correct initiation of embryonic gene expression, and early lineage development in the embryo. Comparative work demonstrates reprogramming in all mammalian species analysed, but the extent and timing varies, consistent with notable differences between species during preimplantation development. Parental imprinting marks originate in sperm and oocytes and are generally protected from this genome-wide reprogramming. Early primordial germ cells possess imprinting marks similar to those of somatic cells. However, rapid DNA demethylation after midgestation erases these parental imprints, in preparation for sex-specific de novo methylation during gametogenesis. Aberrant reprogramming of somatic epigenetic marks after somatic cell nuclear transfer leads to epigenetic defects in cloned embryos and stem cells. Links between epigenetic marking systems appear to be developmentally regulated contributing to plasticity. A number of activities that confer epigenetic marks are firmly established, while for those that remove marks, particularly methylation, some interesting candidates have emerged recently which need thorough testing in vivo. A mechanistic understanding of reprogramming will be crucial for medical applications of stem cell technology.
|
2,337,874 |
Multiple cases of striking genetic similarity between alternate electric fish signal morphs in sympatry.
|
Striking trait polymorphisms are worthy of study in natural populations because they can often shed light on processes of phenotypic divergence and specialization, adaptive evolution, and (in some cases) the early stages of speciation. We examined patterns of genetic variation within and between populations of mormyrid fishes that are morphologically cryptic in sympatry but produce alternate types of electric organ discharge (EOD). Other species in a large group containing a clade of these morphologically cryptic EOD types produce stereotyped, species-typical EOD waveforms thought to function in mate recognition. First, for six populations from Gabon's Brienomyrus species flock, we confirm that forms of electric fish that exhibit distinctive morphologies and unique EOD waveforms (i.e., good reference species) are reproductively isolated from coexisting congeners. These sympatric species deviate from genetic panmixia across five microsatellite loci. Given this result, we examined three focal pairs of syntopic and morphologically cryptic EOD waveform types that are notable exceptions to the pattern of robust genetic partitioning among unique waveform classes within assemblages. These exceptional pairs constitute a monophyletic group within the Brienomyrus flock known as the magnostipes complex. One member of each pair (type I) produces a head-negative EOD, while the other member (either type II or type III, depending on location) produces a longer duration EOD differing in waveform from type I. We show that signal development in these pairs begins with juveniles of all magnostipes-complex morphs emitting head-positive EODs resembling those of type II adults. Divergence of EOD waveforms occurs with growth such that there are two discrete and fixed signal types in morphologically indistinguishable adults at each of several localities. Strong microsatellite partitioning between allopatric samples of any of these morphologically cryptic signal types suggests that geographically isolated populations are genetically decoupled from one another. By contrast, sympatric morphs appear genetically identical across microsatellite loci in Mouvanga Creek and the Okano River and only very weakly diverged, if at all, in the Ivindo River. Our results for the magnostipes complex fail to detect species boundaries between the focal morphs and are, instead, fully consistent with the existence of relatively stable signal dimorphisms at each of several different localities. No mechanism for the maintenance of this electrical polymorphism is suggested by the known natural history of the magnostipes complex. Despite a lack of evidence for genetic differentiation, the possibility of incipient sympatric speciation between morphs (especially type I and type II within the Ivindo River) merits further testing due to behavioral and neurobiological lines of evidence implying a general role for stereotyped EOD waveforms in species recognition. We discuss alternative hypotheses concerning the origins, stability, and evolutionary significance of these intriguing electrical morphs in light of geographical patterns of population structure and signal variation.
|
2,337,875 |
Dispersal in a parasitic worm and its two hosts: consequence for local adaptation.
|
Characterizing host and parasite population genetic structure and estimating gene flow among populations is essential for understanding coevolutionary interactions between hosts and parasites. We examined the population genetic structure of the trematode Schistosoma mansoni and its two host species (the definitive host Rattus rattus and the intermediate host Biomphalaria glabrata) using microsatellite markers. Parasites were sampled from rats. The study was conducted in five sites of the Guadeloupe Island, Lesser Antilles. Mollusks display a pattern of isolation by distance whereas such a pattern is not found neither in schistosomes nor in rats. The comparison of the distribution of genetic variability in S. mansoni and its two host species strongly suggests that migration of parasites is principally determined by that of the vertebrate host in the marshy focus of Guadeloupe. However, the comparison between genetic differentiation values in schistosomes and rats suggests that the efficacy of the schistosome rat-mediated dispersal between transmission sites is lower than expected given the prevalence, parasitic load and migration rate of rats among sites. This could notably suggest that rat migration rate could be negatively correlated to the age or the infection status of individuals. Models made about the evolution of local adaptation in function of the dispersal rates of hosts and parasites suggest that rats and mollusks should be locally adapted to their parasites.
|
2,337,876 |
The psychotherapy of genetics.
|
The evolution of genomic science and its effect on medicine and health care offer opportunities for family therapists to participate in the comprehensive care of patients and families with genetic disorders. This article provides an overview of what we now know about the psychological and interpersonal experience of patients and families facing some of these illnesses. Case examples illustrate the process of decision-making about testing and treatment, and the importance of understanding developmental issues and transgenerational family dynamics in any related psychotherapy. Challenging emotional issues include managing anger, ambivalence, and guilt; challenging interpersonal issues include dealing with differing coping and communication styles, decisions about disclosure and secrets, and conflict resolution. Family-oriented interventions include individual, couple, and family therapy, and psychoeducational groups. Recommendations are made for family therapists to participate as part of the genetic healthcare team.
|
2,337,877 |
Toward a biopsychosocial model for 21st-century genetics.
|
Advances in genomic research are increasingly identifying genetic components in major health and mental health disorders. This article presents a Family System Genetic Illness model to address the psychosocial challenges of genomic conditions for patients and their families, and to help organize this complex biopsychosocial landscape for clinical practice and research. This model clusters genomic disorders based on key characteristics that define types of disorders with similar patterns of psychosocial demands over time. Key disease variables include the likelihood of developing a disorder based on specific genetic mutations, overall clinical severity, timing of clinical onset in the life cycle, and whether effective treatment interventions exist to alter disease onset and/or progression. For disorders in which carrier, predictive, or presymptomatic testing is available, core nonsymptomatic time phases with salient developmental challenges are described pre- and post-testing, including a long-term adaptation phase. The FSGI model builds on Rolland's Family System Illness model, which identifies psychosocial types and phases of chronic disorders after clinical onset. The FSGI model is designed to be flexible and responsive to future discoveries in genomic research. Its utility is discussed for research, preventive screening, family assessment, treatment planning, and service delivery in a wide range of healthcare settings.
|
2,337,878 |
Association analysis of candidate genes for maysin and chlorogenic acid accumulation in maize silks.
|
Two compounds, the C-glycosyl flavone maysin and the phenylpropanoid product chlorogenic acid (CGA), have been implicated in corn earworm (Helicoverpa zea Boddie) resistance in maize (Zea mays L.). Previous quantitative trait locus (QTL) analyses identified the pericarp color (p) locus, which encodes a transcription factor, as the major QTL for maysin and CGA. QTL analysis has also implicated the dihydroflavanol reductase (DFR; E.C. no. 1.1.1.219) locus anthocyaninless1 (a1) and the duplicate chalcone synthase (CHS; E.C. no. 2.3.1.74) loci colorless2 (c2) and white pollen1 (whp1) as genes underlying QTL for maysin and/or CGA synthesis. Epistatic interactions between p and a1 and between p and c2 were also defined. CHS catalyzes the first step in the flavonoid pathway and represents one of the first enzyme steps following the branch off the general phenylpropanoid pathway towards CGA synthesis. In maize, the reduction of dihydroflavanol to leucoanthocyanin by DFR immediately follows the pathway branch leading to C-glycosyl flavone production. The detection of QTLs for maysin and CGA concentration at loci encoding enzyme steps following the pathway branch points implicates alterations in the flow of biochemical intermediates as the biological basis of the QTL effects. To examine if sequence variation among alleles of a1, c2, and whp1 affect maysin and CGA synthesis in maize silks, we performed an association analysis. Because the p locus has often been a major QTL for maysin and CGA and has exhibited epistatic interactions with a1, c2, and whp1, association analysis was conditioned on the p genotype. A highly significant association of two sequence polymorphisms in the promoter of a1 with maysin synthesis was demonstrated. Additional conditioning on the genotype of the significant a1 polymorphism allowed the detection of a significant polymorphism within the whp1 promoter. Our analyses demonstrate that conditioning for epistatic factors greatly increases the power of association testing.
|
2,337,879 |
The antiepidermal growth factor receptor monoclonal antibody cetuximab/C225 reduces hypoxia-inducible factor-1 alpha, leading to transcriptional inhibition of vascular endothelial growth factor expression.
|
We have previously shown that the antiepidermal growth factor receptor monoclonal antibody cetuximab (C225; Erbitux), which was recently approved for the treatment of metastatic colorectal cancer, has antiangiogenic properties, inhibiting vascular endothelial growth factor (VEGF) secretion in culture and in animal models. Here, we have furthered the study by demonstrating that cetuximab reduces cellular levels of hypoxia-inducible factor-1 alpha (HIF-1alpha), a transcriptional regulator of VEGF expression, in A431 epidermoid carcinoma cells under both normoxic and hypoxic culture conditions. Expression of a constitutively active Ras in A431 cells rendered cellular resistance to the cetuximab-mediated reduction of the HIF-1alpha level. Cell lines with naturally occurring phosphatase and tensin homologue deleted on chromosome 10 mutations or deletions were also resistant to cetuximab-mediated reduction of the HIF-1alpha level. Pharmacologic inhibition of phosphatidylinositol 3-kinase with LY294002 reduced the HIF-1alpha level in both normoxic and hypoxic A431 cells, whereas inhibition of the mitogen-activated protein kinase kinase by PD98059 reduced the level of HIF-1alpha only in normoxic A431 cells. In addition, cetuximab reduced the cellular level of HIF-1alpha in the presence of a proteasome inhibitor, lactacystin, indicating that cetuximab acts mainly at the level of protein synthesis. The reduction of HIF-1alpha in response to cetuximab treatment was accompanied by transcriptional inhibition of VEGF expression, measured by a luciferase assay in A431 cells transfected with a vector containing the VEGF hypoxia response element. Taken together, our results indicate that the previously demonstrated inhibition of VEGF by cetuximab occurs at the level of transcription in response to a reduced level of HIF-1alpha and justify further testing of therapeutic strategies that combine cetuximab with approaches inhibiting the function of VEGF or the VEGF receptor.
|
2,337,880 |
Audiologic testing and molecular analysis of 12S rRNA in patients receiving aminoglycosides.
|
Pathogenic mutations in the mitochondrial genome are associated with a wide variety of maternally inherited human diseases including sensorineural hearing loss (HL). A specific mutation, m.1555A>G in the mitochondrial 12S rRNA gene, is associated with predisposition to aminoglycoside ototoxicity and HL. Mutation screening in this gene has been recommended before use of aminoglycosides as a preventative strategy to reduce the risk of ototoxicity.</AbstractText>To study the incidence of mutations in the 12S rRNA gene in patients being treated with aminoglycosides and its correlation with ototoxicity.</AbstractText>Patients undergoing treatment with aminoglycosides were prospectively enrolled in this study (n = 27). Total dosage administered and therapeutic levels of the antibiotic were noted. All patients underwent high-frequency pure-tone audiometry pre- and posttherapy and sequencing of the 12S rRNA gene. In addition, 12S rRNA gene was also sequenced in 50 controls to characterize population specific polymorphisms.</AbstractText>Five of 27 patients suffered from HL involving the high frequencies: four mild and one moderate. Only one of the five patients with ototoxicity harbored two sequence alterations in 12S rRNA of uncertain pathogenicity. The m.1555A>G and m.961delTInsCn mutations were not detected.</AbstractText>High-frequency pure-tone audiometry is critical for detection of aminoglycoside-induced HL. In the Swiss population, screening for mutations in the 12S rRNA gene, before the initiation of aminoglycoside therapy, is not supported by this limited study. A larger multicenter and multicultural study is warranted to more definitively address this critical clinical issue.</AbstractText>
|
2,337,881 |
Subset of individuals with autism spectrum disorders and extreme macrocephaly associated with germline PTEN tumour suppressor gene mutations.
|
The genetic aetiology of autism remains elusive. Occasionally, individuals with Cowden syndrome (a cancer syndrome) and other related hamartoma disorders such as Bannayan-Riley-Ruvalcaba syndrome, Proteus syndrome, and Proteus-like conditions, are characterised by germline PTEN mutations, and may have neurobehavioural features resembling autism as well as overgrowth and macrocephaly. Therefore, we undertook PTEN gene mutation analysis in 18 subjects mainly prospectively ascertained with autism spectrum disorder and macrocephaly. Of these 18 autistic subjects (13 males and five females; ages 3.1-18.4 years) with a head circumference range from 2.5 to 8.0 standard deviations above the mean, three males (17%) carried germline PTEN mutations. These three probands had previously undescribed PTEN mutations: H93R (exon 4), D252G (exon 7), and F241S (exon 7). They had the larger head circumference measurements amongst all our study subjects. The three residues altered in our patients were highly evolutionarily conserved. We suggest that PTEN gene testing be considered for patients with autistic behaviour and extreme macrocephaly. The gene findings may impact on recurrence risks as well as medical management for the patient.
|
2,337,882 |
Do preclinical testing strategies help predict human hepatotoxic potentials?
|
Overt hepatotoxicity due to drug administration is a real and present issue in drug development and regulatory circles. Preclinical drug development is intended to identify potential risks and target tissues prior to introduction of new molecular entities into the human population. The standard regimen is testing at various multiples of the intended human therapeutic dose in at least 2 species of animals, one rodent (rats or mice), one non-rodent (dogs,nonhuman primates, minipigs, and rabbits, as examples) for at least two weeks of repeated dosing. Experience has shown that this regimen "works"most of the time. However, preclinical models are not infallible and are not always predictive. Whether the lack of predictivity is due to individual human genetic sensitivities, immunologically mediated phenomena, disease mediation or idiosyncratic reactions, the animal models are limited in detecting these characteristics and other low incidence phenomena. While it is uncommon for drug developers to continue development with products that elicit overt hepatic toxicity early in the animal testing, some products have made it through the approval process and then shown significant adverse effects. Some of the drugs (acetaminophen, isoniazid, trovafloxacin, troglitazone, bromfenac, clarithromycin, telithromycin) that have shown this propensity will be discussed in detail from early preclinical development to marketing and, in some instances, to limitations to usage or removal from the U.S. marketplace.
|
2,337,883 |
Lesch-Nyhan Disease.
|
The first description of Lesch-Nyhan disease was in 1964; the first two patients were seen in 1963. The disease has caught the imagination of a variety of clinicians and scientists. The clinical picture is striking, combining spasticity, involuntary movements, and cognitive retardation with self-injurious behavior and the manifestations of gout. Biochemically, the overproduction of uric acid--the end product of purine metabolism--was, when measured, the largest ever seen. The disease is now well understood on a molecular basis. Enzyme analysis and mutational analysis have made available a full range of genetic testing, including diagnosis, carrier detection, and prenatal diagnosis. Therapy with allopurinol has been effective for those manifestations the disease shares with gout. Treatment for the neurological and behavioral features of the disease remains elusive.
|
2,337,884 |
Rare mutations at codon 103 of HIV-1 reverse transcriptase can confer resistance to non-nucleoside reverse transcriptase inhibitors.
|
The K103N mutation in HIV-1 reverse transcriptase (RT) confers high-level resistance to current non-nucleoside reverse transcriptase inhibitors (NNRTI). The prevalence and resistance profile of HIV-1 with other substitutions at RT codon 103 is less well documented.</AbstractText>K103 substitutions among over 70,000 clinical samples submitted for routine antiretroviral resistance testing at two independent centres were examined. Phenotypic resistance profiles of isolates harboring rare K103 variants in the absence of known NNRTI-associated resistance mutations were retrieved from Virco's correlative genotype/phenotype database. Genotyped samples with known treatment histories were retrieved from the British Columbia Centre for Excellence in HIV/AIDS database. Site-directed mutants containing K103 variants were constructed and phenotyped.</AbstractText>K103N, R and S were observed in 29, 1.8, and 0.9% of Virco isolates and in 16, 1.5 and 0.4% of British Columbia isolates. K103T/Q/H substitutions were observed only rarely (<0.2%). The prevalence of unusual codon 103 substitutions remained stable over 5 years, except K103S, which increased over fourfold in both datasets. K103R/Q-containing clinical isolates remained phenotypically susceptible to NNRTI, whereas K103S/T/H-containing isolates showed over 10-fold decreased NNRTI susceptibility. Among patients with a known treatment history, K103S/T/H were observed primarily in individuals failing NNRTI-containing regimens. Site-directed mutants confirmed decreased susceptibility to NNRTI in K103S/T/H-containing recombinants.</AbstractText>Variants at HIV RT codon 103 other than K103N are observed relatively rarely in clinical isolates, but K103 S, T and H confer decreased susceptibility to NNRTI. These data are relevant for interpretive genotype algorithms and in the design of assays specific to RT codon 103 mutations.</AbstractText>
|
2,337,885 |
Identification of Panax species in the herbal medicine preparations using gradient PCR method.
|
In order to identify the existence of Panax species in herbal medicine preparations, the Ginseng specific marker primer was selected and created based on the sequence of Korean ginseng DNA fragment, 359 bp. The gradient PCR was performed on 40 types of the herbal medicines including the 7 types of Araliaceae that are in the same family with the Panax ginseng using the created Ginseng maker primer. As result, Panax notoginseng (Chinese), Panax japonicus (Japanese) and Panax quinquefolius (American), along with Panax ginseng (Korean) were the only ones amplified. However, in the case of Atractylodes lancea, one of the herbal medicines not categorized as Panax species, the DNA was prominently amplified by the Ginseng marker primer. The sequence of the amplified DNA of Atractylodes lancea was identified, resulting in enabling the differentiation from the Panax species by the Restriction Fragment Length Polymorphisms (RFLP) method. In addition, the results of the gradient PCR performed on the herbal medicine preparations that consists of Panax ginseng showed that 290 bp size of the original DNA fragments of Panax ginseng was amplified on the herbal medicine preparations containing Panax ginseng. Therefore, these results suggest a possibility of creating a new testing method for identifying specific herb medicines using the gradient PCR, a molecular biological method not only on Panax ginseng, but also on other herbal medicines and herbal medicine preparations.
|
2,337,886 |
The incidental discovery of nonpaternity through genetic carrier screening: an exploration of lay attitudes.
|
With advances in genetic medicine, paternity is increasingly being determined by genetic rather than social markers. In this article, the author examines the complex nature of paternity and the way in which it has been constructed socially, legally, and medically. She then presents the results from an empirical study on public attitudes toward genetic testing and paternity. In particular, she examines lay attitudes toward an ethical dilemma posed by the incidental discovery of nonpaternity during the process of genetic testing for a recessively inherited disease. She concludes the article by drawing attention to the potential problems inherent in the intervention of genetic medicine into family relationships.
|
2,337,887 |
A general framework for statistical linkage analysis in multivalent tetraploids.
|
In multivalent polyploids, simultaneous pairings among homologous chromosomes at meiosis result in a unique cytological phenomenon-double reduction. Double reduction casts an impact on chromosome evolution in higher plants, but because of its confounded effect on the pattern of gene cosegregation, it complicates linkage analysis and map construction with polymorphic molecular markers. In this article, we have proposed a general statistical model for simultaneously estimating the frequencies of double reduction, the recombination fraction, and optimal parental linkage phases between any types of markers, both fully and partially informative, or dominant and codominant, for a tetraploid species that undergoes only multivalent pairing. This model provides an in-depth extension of our earlier linkage model that was built upon Fisher's classifications for different gamete formation modes during the polysomic inheritance of a multivalent polyploid. By implementing a two-stage hierarchical EM algorithm, we derived a closed-form solution for estimating the frequencies of double reduction through the estimation of gamete mode frequencies and the recombination fraction. We performed different settings of simulation studies to demonstrate the statistical properties of our model for estimating and testing double reduction and the linkage in multivalent tetraploids. As shown by a comparative analysis, our model provides a general framework that covers existing statistical approaches for linkage mapping in polyploids that are predominantly multivalent. The model will have great implications for understanding the genome structure and organization of polyploid species.
|
2,337,888 |
The gallbladder and biliary tract in cystic fibrosis.
|
Chronic liver disease is a major complication of cystic fibrosis. Its incidence and severity are variable, and diagnosis relies on a combination of clinical evaluation, biochemical testing, and radiologic assessment. Identifying patients who have early disease is critical, and the administration of ursodeoxycholic acid appears to be beneficial. The pathogenesis is incompletely understood, and factors that contribute to the variability in incidence and severity are unknown. Fortunately, only a small proportion of individuals progress to advanced liver disease; however, in this population, there is significant morbidity and impairment in quality of life. Liver transplantation can be performed successfully in patients with end-stage liver disease. Future treatments involve targeted gene therapy and activation of mutant forms of the cystic fibrosis transmembrane conductance regulator.
|
2,337,889 |
Meta-analysis in psychiatric genetics.
|
The article reviews literature on methods for meta-analysis of genetic linkage and association studies, and summarizes and comments on specific meta-analysis findings for psychiatric disorders. The Genome Scan Meta-Analysis and Multiple Scan Probability methods assess the evidence for linkage across studies. Multiple Scan Probability analysis suggested linkage of two chromosomal regions (13q and 22q) to schizophrenia and bipolar disorder, whereas Genome Scan Meta-Analysis on a larger sample identified at least 10 schizophrenia linkage regions, but none for bipolar disorder. Meta-analyses of pooled ORs support association of schizophrenia to the Ser311Cys polymorphism in DRD2 and the T102C polymorphism in HTR2A, and of attention deficit hyperactivity disorder to the 48-bp repeat in DRD4. The 5-HTTLPR polymorphism in the serotonin transporter gene (SLC6A4) may contribute to the risk of bipolar disorder, suicidal behavior, and neuroticism, but association to the lifetime risk of major depression has not been shown. Meta-analyses support linkage of schizophrenia to regions where replicable associations to candidate genes have been identified through positional cloning methods. There are additional supported regions where susceptibility genes are likely to be identified. Linkage meta-analysis has had less clear success for bipolar disorder based on a smaller dataset. Meta-analysis can guide the prioritization of regions for study, but proof of association requires biological confirmation of hypotheses about gene actions. Elucidation of causal mechanisms will require more comprehensive study of sequence variation in candidate genes, better statistical and meta-analytic methods to take all variation into account, and biological strategies for testing etiologic hypotheses.
|
2,337,890 |
Ebrii gignunt ebrios--One drunkard begets another: the genetics of alcohol dependence.
|
Family, twin, and adoption studies provide convincing evidence of a genetic contribution to the predisposition to alcohol dependence. Two main molecular genetic approaches, namely linkage and association, have been adopted to identify the genes that underpin that genetic vulnerability. Robust findings have implicated genes involved in alcohol metabolism, particularly when studied in Asian populations. These include the genes encoding aldehyde dehydrogenase 2 and several alcohol dehydrogenases. Other findings have proven to be less resilient, but have often implicated genes of the dopaminergic, GABA-ergic and serotonergic systems. Improvements in sample collection and characterization, technological and statistical advances, combined with a developmental approach, should enable molecular genetics to deliver on its initial promise of identifying the genes involved. These findings will have important implications for the identification and targeting of treatment. However it is anticipated that this information will have little impact on risk alteration and consequently population screening will be highly unlikely. Genetic factors always should be considered in the context of their developmental interplay with those of the environment.
|
2,337,891 |
Accurate genetic testing platform based on haploid templates: Use in inheritable colon cancer.
|
Extract: The misfortune of individuals having inherited a genetic mutation that predisposes them to cancer can become a weapon for their better management of the disease and the rest of their family members. This is what the promise of genetic testing is: to reduce the mortality and morbidity through screening, and hopefully lead to early diagnosis and even prevention of spread or the cancer itself. Inherited forms of cancer represent a good example of the benefits and complications of genetic testing. A single inherited mutant gene usually is enough to confer a high risk of cancer. The mutation is inherited from one of the parents and it is transmitted to the offspring. Other siblings may also have inherited the mutant gene. This way, some members of the family will have that one mutation and some will not. Therefore, when an inherited mutation is identified in one member of a family, the rest of the family members can be screened for the presence of this mutation. So, the mutation can be identified early, before any clinical symptoms, and this allows the potential disorder to be managed appropriately.
|
2,337,892 |
Evaluation of peripheral neuropathy. Part III: vasculitic, infectious, inherited, and idiopathic neuropathies.
|
In this, the third of a 3-part series on peripheral neuropathy, the syndromes of vasculitic, infectious, inherited, and idiopathic neuropathy are discussed. Vasculitis is a frequent cause of neuropathy in the setting of a connective tissue disease. The infectious neuropathies most likely to be encountered in the United States are those due to varicella-zoster virus, human immunodeficiency virus, Lyme disease, hepatitis C virus, and, most recently, West Nile virus. Inherited neuropathies are divided into 2 main types: predominant motor or predominant sensory. The former are generally classed as the Charcot-Marie-Tooth diseases and the latter as the hereditary sensory neuropathies. Each category has a number of different subtypes. If the results of routine screening tests are negative, the clinician must consider special testing for unusual disorders, including evaluations for underlying autoimmune or malignant disorders, genetic tests for inherited neuropathies, and other unusual or selectively ordered tests. These tests are very expensive and should be ordered only after the common causes of neuropathy are excluded. Unless the neuropathy can be substantially alleviated or cured, symptomatic treatment (most often for pain) plays a significant role for these patients.
|
2,337,893 |
Genetic factors in pancreatitis.
|
The understanding of pathogenesis of acute and chronic pancreatitis has benefited from the progress made in genetic investigations. The discoveries of the gain of function mutations of cationic trypsinogen gene (PRSS1) and the loss of function mutations of pancreatic secretory trypsin inhibitor (SPINK 1) or other potential defects in genes that regulate pancreatic secretory function or modulate inflammatory response to pancreatic injury has changed our current concepts on the pathogenesis of pancreatitis. Genetic factors play an important role in the susceptibility to pancreatic injury, severity and evolution of inflammatory process, leading in some cases to chronic inflammation and/or fibrosis. Acute pancreatitis is viewed as an event and chronic pancreatitis as a process, sequentially linked, reflecting a complex interaction between genetic and environmental factors.
|
2,337,894 |
Pathogenic effects of a novel heterozygous R350P desmin mutation on the assembly of desmin intermediate filaments in vivo and in vitro.
|
Mutations of the human desmin gene on chromosome 2q35 cause a familial or sporadic form of skeletal myopathy frequently associated with cardiac abnormalities. Here, we report the pathogenic effects of a novel heterozygous R350P desmin missense mutation, which resides in the evolutionary highly conserved coil 2B domain of the alpha-helical coiled-coil desmin rod domain, on the assembly of desmin intermediate filaments (IF) in cultured cells and in vitro. By transfection experiments, we show that R350P desmin is incapable of de novo formation of a desmin IF network in vimentin-free BMGE+H, MCF7 and SW13 cells and that it disrupts the endogenous vimentin cytoskeleton in 3T3 fibroblast cells. Hence, transfected cells displayed abnormal cytoplasmic protein aggregates reminiscent of desmin-positive protein deposits seen in the immunohistochemical and ultrastructural analysis of skeletal muscle derived from the index patient of the affected family. To study the functional effects of the R350P desmin mutation at the protein level, we performed in vitro assembly studies with wild-type (WT) and mutant desmin protein. Our analysis revealed that the in vitro assembly process of R350P desmin is already disturbed at the unit length filament level and that further association reactions generate huge, tightly packed protein aggregates. On assessing the pathogenic effects of R350P desmin in various mixtures with WT desmin, we show that a ratio of 1 : 3 (R350P desmin/WT desmin) is sufficient to effectively block the normal polymerization process of desmin IFs. Our findings indicate that the heterozygous R350P desmin mutation exerts a dominant negative effect on the ordered lateral arrangement of desmin subunits. This disturbance of the lateral packing taking place in the first phase of assembly is ultimately leading to abnormal protein aggregation.
|
2,337,895 |
Low effective population size and evidence for inbreeding in an overexploited flatfish, plaice (Pleuronectes platessa L.).
|
Overexploitation and subsequent collapses of major worldwide fisheries has made it clear that marine stocks are no inexhaustible. Unfortunately, the perception remains that marine fished are resilient to large population reductions, as even a commercially 'collapsed' stock will still consist of millions of individuals. Coupled with this notion is the idea that fisheries can, therefore, have little effect on the genetic diversity of stocks. We used DNA from archived otoliths collected between 1924 and 1972 together with 2002 juvenile;s tissue to estimate effective population size (Ne) in plaice (Pleuronrctes platessa). Ne was estimated at 20,000 in the North Sea and 2000 in Iceland. These values are five orders of magnitude smaller than the estimated census size foe the two locations. Populations examined between 1924 and 1960 were in Hardy-Weinberg equilibrium, whereas populations examined after 1970 were not. Extensive testing was performed to rule out genotyping artefacts and Wahlund effects. The significant heterozygote deficiencies found from 1970 onward were attributed to inbreeding. The emergence of inbreeding between 1905 and 19070 coincides with the increase in fishing mortality after World War II. Although the biological mechanisms remain speculative, our demonstration of inbreeding signals the need for understanding the social and mating behaviour in commercially important fishes.
|
2,337,896 |
Molecular analysis of the NDP gene in two families with Norrie disease.
|
To describe the molecular defects in the Norrie disease protein (NDP) gene in two families with Norrie disease (ND).</AbstractText>We analysed two families with ND at molecular level through polymerase chain reaction, DNA sequence analysis and GeneScan.</AbstractText>Two molecular defects found in the NDP gene were: a missense mutation (265C > G) within codon 97 that resulted in the interchange of arginine by proline, and a partial deletion in the untranslated 3' region of exon 3 of the NDP gene. Clinical findings were more severe in the family that presented the partial deletion. We also diagnosed the carrier status of one daughter through GeneScan; this method proved to be a useful tool for establishing female carriers of ND.</AbstractText>Here we report two novel mutations in the NDP gene in Mexican patients and propose that GeneScan is a viable mean of establishing ND carrier status.</AbstractText>
|
2,337,897 |
Developments in infertility therapy--diagnosis of genetic disease in embryos.
|
The general practitioner plays a vital role in assisting couples through the difficult and emotional field of assisted reproductive techniques including in vitro fertilisation (IVF).</AbstractText>This article discusses the most recent developments in IVF so that GPs may better explain this ever changing field of medicine to their patients.</AbstractText>This article begins by explaining how sperm can be brought together with oocytes for fertilisation outside the body, and then moves on to selecting the most genetically appropriate embryos for implantation. From this comes the issue of examining the fertilised oocytes to detect abnormalities, and the options available to couples with ethical concerns. The promise of regenerative medicine through the use of sperm cells is also discussed.</AbstractText>
|
2,337,898 |
The ART of assisted reproductive technology.
|
One in six Australian couples of reproductive age experience difficulties in conceiving a child. Once a couple has been appropriately assessed, assisted reproductive technology (ART) techniques can be used to overcome problems with ovulation, tubal patency, male fertility or unexplained infertility.</AbstractText>This article discusses the range of ART techniques available to subfertile couples.</AbstractText>Intracytoplasmic sperm injection is now the most common form of ART used in Australia, being used in almost half of all fresh cycles, with in vitro fertilisation being used in approximately one-third of all fresh cycles.</AbstractText>
|
2,337,899 |
Genetic variation and relationships at six VNTR loci in two distinct sample populations in Brazil.
|
The Brazilian population has been the focus of intensive genetic study due to admixture characteristics whereas there are few reports on the variability of VNTR loci in Brazil.</AbstractText>The aim of this study was to analyse genetic parameters in sample populations from two geographically distant regions: São Luis City, in Maranhão State and Campinas City, in São Paulo State. We investigated if distinct colonization influences could produce detectable differences in genetic background.</AbstractText>DNA samples from peripheral drained blood were obtained from unrelated individuals who underwent paternity testing. Allelic variation in six VNTR loci (D2S44, D4S139, D5S110, D8S358, DI0S28 and D17S79) was evaluated. The results were compared to reference databases available for general Latin-derived European and African-American populations as well as for other Brazilian groups.</AbstractText>This study reveals that forensic population parameters did not show differences among regions, although we detected admixture values varying between the south-east and north-east of Brazil.</AbstractText>Differences between the two samples are probably due to different admixture proportions of European- and African-derived alleles in each region: both populations are in Hardy Weinberg equilibrium. In addition, the allelic frequency for all loci, in both populations, can be used as database for forensic purposes.</AbstractText>
|
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.