Project description:Cases with Type 1 Diabetes (T1D) in the UK, were part of the Wellcome Trust Case Control Consortium (WTCCC) - <a href="http://www.wtccc.org.uk" target="_blank">http://www.wtccc.org.uk</a> - that first reported in 2007: Wellcome Trust Case Control Consortium (2007) Genome-wide association study of 14,000 cases of seven common diseases and 3,000 shared controls. Nature, 447, 661-678. [PubMed: <a href="http://www.ncbi.nlm.nih.gov/pubmed/17554300" target="_blank">17554300</a>] In this genome-wide association study (GWAS), funded by the NIH and JDRF, and sponsored by the Type 1 Diabetes Genetics Consortium (T1DGC), we were able to extend the case and control groups used in the WTCCC, with the intention of performing a well-powered meta-analysis. The study is written up as: Barrett, J.C., Clayton, D.G., Concannon, P., Akolkar, B., Cooper, J.D., Erlich, H.A., Julier, C., Morahan, G., Nerup, J., Nierras, C., Plagnol, V., Pociot, F., Schuilenburg, H., Smyth, D.J., Stevens, H., Todd, J.A., Walker, N.M., Rich, S.S. and The Type 1 Diabetes Genetics Consortium Genome-wide association study and meta-analysis find that over 40 loci affect risk of type 1 diabetes. Nature Genetics, PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/19430480" target="_blank">19430480</a>. Resources - data: * Case data from this study is deposited here (i.e. in dbGaP) * Control data from this experiment - with subjects from the 1958 British Birth Cohort - is deposited with the European Genotype Archive (EGA): <a href="http://www.ebi.ac.uk/ega/" target="_blank">http://www.ebi.ac.uk/ega/</a> from where the WTCCC data is also available. * A complete description of how to request all components of the meta-analysis is available at: <a href="http://www.t1dbase.org/page/PosterView/display/poster_id/324" target="_blank">http://www.t1dbase.org/page/PosterView/display/poster_id/324</a> * Additional genetic data on the same case subjects, including some HLA types, are available from the Juvenile Diabetes Research Foundation/Wellcome Trust Diabetes and Inflammation Laboratory (JDRF/WT-DIL): <a href="http://www-gene.cimr.cam.ac.uk/todd/" target="_blank">http://www-gene.cimr.cam.ac.uk/todd/</a> Resources - samples: Case and control DNA samples are also available: * Case DNA samples are available from the JDRF/WT-DIL, as above, and will be available from the NIDDK Genetics Repository at Rutgers: <a href="https://www.niddkrepository.org" target="_blank">https://www.niddkrepository.org</a> * Control DNA samples are available from the 1958 British Birth Cohort (aka National Child Development Study): <a href="http://www.cls.ioe.ac.uk/studies.asp?section=000100020003" target="_blank">http://www.cls.ioe.ac.uk/studies.asp?section=000100020003</a> Use restrictions: There are access limitations to both data and samples, in order to keep their use in line with subjects' consent.

Project description:BackgroundAutoimmune thyroiditis occurs in 10-25% of patients with type 1 diabetes (T1D). Most of these patients are also positive for thyroid peroxidase (TPO) antibodies. Thyroid dysfunction complicates T1D metabolic control and is a component of the autoimmune polyglandular syndrome (APS, type 2 or 3). Previous studies of isolated T1D and of T1D combined with other autoimmune disorders showed genetic susceptibility for alleles in HLA-DQB1 and -DRB1 and also CTLA4 and PTPN22.Research design and methodsWe analyzed the Type 1 Diabetes Genetics Consortium Autoantibody Workshop data by differentiating those T1D probands with and without TPO antibodies or thyroid disease with respect to polymorphisms in HLA, CTLA4, INS, PTPN22, and VDR, taking into account the ethnic origin. Genotype and clinical/immunogenic phenotype data were analyzed by gene counting methods and logistic regression analysis.ResultsThe presence of TPO antibodies (25.2%) and thyroid disease (8.4%) was associated with older age, female sex, and presence of other autoantibodies (GAD65, ATPase, 21-OH) (all P<0.001). The highest prevalence was in patients of Hispanic ancestry (31%) and the lowest in those of African ancestry (8%). In T1D non-Hispanic whites, HLA-DRB1*0101 is significantly (P<0.0001) less frequent in TPO-positive than in TPO-negative individuals, whereas HLA-DRB1*0404, -DQB1*0301, and -DPB1*0201 are significantly (P<0.0001) more frequent. Subjects with a high titer of TPO autoantibodies and with thyroid disease were associated with female sex and older age and negatively associated with DRB1*0401-DQB1*0302 (P<0.0001). No significant differences were observed for an association of TPO positivity or thyroid disease with single nucleotide polymorphisms in the INS, CTLA4, or VDR loci, with nominal significance (P=0.01) for PTPN22 R620W variant.ConclusionsThyroid autoimmunity is highly prevalent in T1D patients of non-Hispanic white, Asian, or Hispanic origin. The strongest disease risk is conferred by female sex and older age. This risk is modulated by HLA-DRB1 and HLA-DPB1 loci. The immunogenetic profile for T1D with thyroid autoimmunity may identify distinct pathways regulating polyglandular autoimmunity and disease.

Project description:Although human leukocyte antigen (HLA) DQ and DR loci appear to confer the strongest genetic risk for type 1 diabetes, more detailed information is required for other loci within the HLA region to understand causality and stratify additional risk factors. The Type 1 Diabetes Genetics Consortium (T1DGC) study design included high-resolution genotyping of HLA-A, B, C, DRB1, DQ, and DP loci in all affected sibling pair and trio families, and cases and controls, recruited from four networks worldwide, for analysis with clinical phenotypes and immunological markers.In this article, we present the operational strategy of training, classification, reporting, and quality control of HLA genotyping in four laboratories on three continents over nearly 5 years.Methods to standardize HLA genotyping at eight loci included: central training and initial certification testing; the use of uniform reagents, protocols, instrumentation, and software versions; an automated data transfer; and the use of standardized nomenclature and allele databases. We implemented a rigorous and consistent quality control process, reinforced by repeated workshops, yearly meetings, and telephone conferences.A total of 15,246 samples have been HLA genotyped at eight loci to four-digit resolution; an additional 6797 samples have been HLA genotyped at two loci. The genotyping repeat rate decreased significantly over time, with an estimated unresolved Mendelian inconsistency rate of 0.21%. Annual quality control exercises tested 2192 genotypes (4384 alleles) and achieved 99.82% intra-laboratory and 99.68% inter-laboratory concordances.The chosen genotyping platform was unable to distinguish many allele combinations, which would require further multiple stepwise testing to resolve. For these combinations, a standard allele assignment was agreed upon, allowing further analysis if required.High-resolution HLA genotyping can be performed in multiple laboratories using standard equipment, reagents, protocols, software, and communication to produce consistent and reproducible data with minimal systematic error. Many of the strategies used in this study are generally applicable to other large multi-center studies.

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Type 1 Diabetes Genetics Consortium: A multi-ancestry, genome-wide association study of type 1 diabetes

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