Localization of type 1 diabetes susceptibility to the MHC class I genes HLA-B and HLA-A

The major histocompatibility complex (MHC) on chromosome 6 is associated with susceptibility to more common diseases than any other region of the human genome, including almost all disorders classified as autoimmune. In type 1 diabetes the major genetic susceptibility determinants have been mapped to the MHC class II genes HLA-DQB1 and HLA-DRB1 (refs 1-3), but these genes cannot completely explain the association between type 1 diabetes and the MHC region. Owing to the region's extreme gene density, the multiplicity of disease-associated alleles, strong associations between alleles, limited genotyping capability, and inadequate statistical approaches and sample sizes, which, and how many, loci within the MHC determine susceptibility remains unclear. Here, in several large type 1 diabetes data sets, we analyse a combined total of 1,729 polymorphisms, and apply statistical methods - recursive partitioning and regression - to pinpoint disease susceptibility to the MHC class I genes HLA-B and HLA-A (risk ratios >1.5; Pcombined = 2.01 × 10-19 and 2.35 × 10-13, respectively) in addition to the established associations of the MHC class II genes. Other loci with smaller and/or rarer effects might also be involved, but to find these, future searches must take into account both the HLA class II and class I genes and use even larger samples. Taken together with previous studies, we conclude that MHC-class-I-mediated events, principally involving HLA-B*39, contribute to the aetiology of type 1 diabetes. ©2007 Nature Publishing Group

A nonsense mutation in exon 2 of the DNase I gene is not present in UK subjects with systemic lupus erythematosus and Graves' disease: Comment on the article by Rood et al

No abstract available

Prevalence and relative risk of other autoimmune diseases in subjects with autoimmune thyroid disease

Background: Common autoimmune disorders tend to coexist in the same subjects and to cluster in families. Methods: We performed a cross-sectional multicenter study of 3286 Caucasian subjects (2791 with Graves' disease; 495 with Hashimoto's thyroiditis) attending UK hospital thyroid clinics to quantify the prevalence of coexisting autoimmune disorders. All subjects completed a structured questionnaire seeking a personal and parental history of common autoimmune disorders, as well as a history of hyperthyroidism or hypothyroidism among parents. Results: The frequency of another autoimmune disorder was 9.67 in Graves' disease and 14.3 in Hashimoto's thyroiditis index cases (P = .005). Rheumatoid arthritis was the most common coexisting autoimmune disorder (found in 3.15 of Graves' disease and 4.24 of Hashimoto's thyroiditis cases). Relative risks of almost all other autoimmune diseases in Graves' disease or Hashimoto's thyroiditis were significantly increased (>10 for pernicious anemia, systemic lupus erythematosus, Addison's disease, celiac disease, and vitiligo). There was relative "clustering" of Graves' disease in the index case with parental hyperthyroidism and of Hashimoto's thyroiditis in the index case with parental hypothyroidism. Relative risks for most other coexisting autoimmune disorders were markedly increased among parents of index cases. Conclusion: This is one of the largest studies to date to quantify the risk of diagnosis of coexisting autoimmune diseases in more than 3000 index cases with well-characterized Graves' disease or Hashimoto's thyroiditis. These risks highlight the importance of screening for other autoimmune diagnoses if subjects with autoimmune thyroid disease present with new or nonspecific symptoms. © 2010 Elsevier Inc. All rights reserved

A novel and major association of HLA-C in Graves' disease that eclipses the classical HLA-DRB1 effect

Association of the major histocompatibility complex (MHC) class II-encoded ]HLA-DRB1-DQA1-DQB1 haplotype with Graves' disease (GD) has been known for several years. Recent evidence from other autoimmune diseases has suggested that the HLA class I encoded HLA-B/-C molecules could be conferring HLA-DRB1-DQA1-DQB1 independent effects on disease. The aim of this study was to determine the effect of HLA-B and HLA-C in GD in a white ethnic group of 806 patients with GD and 487 control subjects from the UK. Of the five loci (HLA-B, -C, -DRB1, -DQA1, -DQB1), HLA-C demonstrated the strongest association (P = 1.20 � 10-20) with HLA-C*07 predisposing OR = 1.63, 95% CI (1.23-2.17) and both HLA-C*03 OR = 0.54, 95% CI (0.38-0.77), HLA-C*16 OR = 0.36, 95% CI (0.21-0.61) protective. The other loci were then tested for HLA-C-independent associations. HLA-B was found to be associated independently of HLA-C (P = 1.54 � 10-6) with the other three loci, HLA-DRB1, HLA-DQB1 and HLA-DQA1, also improving the model but with less confidence (P > 10-5). This study has for the first time provided evidence of a primary association of HLA-C, and to a lesser extent HLA-B, with GD. Class II loci could still have effects on GD, but they appear smaller than the HLA-C association. A full investigation of the MHC region, including all class I and II loci is now required. Our results point to a primary role for class I-mediated responses in GD, a condition classically assumed to be a straightforward HLA-class II-restricted autoantibody response to the thyroid stimulating hormone receptor. © The Author 2007. Published by Oxford University Press. All rights reserved

Association of the TSHR gene with Graves' disease: the first disease specific locus

The development of autoimmune thyroid disease (AITD) is associated with autoantibodies directed against the thyroid stimulating hormone receptor (TSHR). Previous studies have failed to demonstrate a consistent association between the TSHR and AITD, or any of its sub-phenotypes. In the present study, we analysed the linkage disequilibrium (LD) structure encompassing the TSHR, to identify LD 'blocks' and SNPs, which capture the majority of intra-block haplotype diversity. The haplotype tagging SNPs, plus all common SNPs reported in previous studies were genotyped in 1059 AITD Caucasian cases and 971 Caucasian controls. A haplotype, across two LD blocks, showed association (P<1 × 10-6, OR 1.7) with Graves' disease (GD) but not autoimmune hypothyroidism (AIH). We replicated these findings by genotyping the most associated GD SNP, rs2268458, in a separate UK Caucasian cohort of 1366 AITD cases and 1061 controls (GD, P =2 × 10-6, OR 1.3; AIH, P =NS). These results in two independent Caucasian data sets suggest that the TSHR is the first replicated GD-specific locus meriting further fine mapping and functional analysis to identify the aetiological variants. © 2005 Nature Publishing Group. All rights reserved

Robust associations of four new chromosome regions from genome-wide analysis of type 1 diabetes

The Wellcome Trust Case Control Consortium (WTCCC) primary genome-wide association (GWA) scan on seven diseases, including the multifactorial autoimmune disease type 1 diabetes (T1D), shows associations at P smaller than 5 x 10-7 between T1D and six chromosome regions: 12q24, 12q13, 16p13, 18p11, 12p13 and 4q27. Here, we attempted to validate these and six other top findings in 4,000 individuals with T1D, 5,000 controls and 2,997 family trios independent of the WTCCC study. We confirmed unequivocally the associations of 12q24, 12q13, 16p13 and 18p11 (P follow-up smaller than or equal to 1.35 x 10 -9; P overall smaller than or equal to 1.15 x 10-14), leaving eight regions with small effects or false-positive associations. We also obtained evidence for chromosome 18q22 (P overall = 1.38 x 10-8) from a GWA study of nonsynonymous SNPs. Several regions, including 18q22 and 18p11, showed association with autoimmune thyroid disease. This study increases the number of T1D loci with compelling evidence from six to at least ten. © 2007 Nature Publishing Group