Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011854 (type 1 diabetes)
 20,749 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The major histocompatibility complex (MHC) is known to harbour genetic risk factors for type 1 diabetes (T1D) additional to the class II determinants HLA-DRB1, -DQA1 and -DQB1, but strong linkage disequilibrium (LD) has made efforts to establish their location difficult. This study utilizes a dataset generated by the T1D genetics consortium (T1DGC), with genotypes for 2965 markers across the MHC in 2321 T1D families of multiple (mostly Caucasian) ethnicities. Using a comprehensive approach consisting of complementary conditional methods and LD analyses, we identified three regions with T1D association, independent both of the known class II determinants and of each other. A subset of polymorphisms that could explain most of the association in each region included single nucleotide polymorphisms (SNPs) in the vicinity of HLA-G, particular HLA-B and HLA-DPB1 alleles, and SNPs close to the COL11A2 and RING1 genes. Apart from HLA-B and HLA-DPB1, all of these represent novel associations, and subpopulation analyses did not indicate large population-specific differences among Caucasians for our findings. On account of the unusual genetic complexity of the MHC, further fine mapping is demanded, with the possible exception of HLA-B. However, our results mean that these efforts can be focused on narrow, defined regions of the MHC.
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PMID:Conditional analyses on the T1DGC MHC dataset: novel associations with type 1 diabetes around HLA-G and confirmation of HLA-B. 1883 Feb 48

The main genetic predisposition to type 1 diabetes (T1D) is known to be conferred by the HLA-DRB1, -DQA1 and -DQB1 genes in the major histocompatibility complex (MHC). Other genetic factors within this complex are known to contribute, but their identity has often been controversial. This picture is shared with several other autoimmune diseases (AIDs). Moreover, as common genetic factors are known to exist between AIDs, associations reported with other AIDs may also be involved in T1D. In this study, we have used these observations in a candidate gene approach to look for additional MHC risk factors in T1D. Using complementary conditional methods (involving conditional logistic regression and family-based haplotype tests) and analyses of linkage disequilibrium (LD) patterns, we confirmed association for alleles of the HLA-A and HLA-B genes and found preliminary evidence for a novel association of a single-nucleotide polymorphism (rs2259571) in the AIF1 gene, independent of the DRB1-DQA1-DQB1 genes and of each other. However, no evidence of independent associations for a number of previously suggested candidate polymorphisms was detected. Our results illustrate the importance of a comprehensive adjustment for LD effects when performing association studies in this complex.
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PMID:Genetic variants of the HLA-A, HLA-B and AIF1 loci show independent associations with type 1 diabetes in Norwegian families. 1898 44

The HLA region encodes several molecules that play key roles in the immune system. Strong association between the HLA region and autoimmune disease (AID) has been established for over fifty years. Association of components of the HLA class II encoded HLA-DRB1-DQA1-DQB1 haplotype has been detected with several AIDs, including rheumatoid arthritis, type 1 diabetes and Graves' disease. Molecules encoded by this region play a key role in exogenous antigen presentation to CD4+ Th cells, indicating the importance of this pathway in AID initiation and progression. Although other components of the HLA class I and III regions have also been investigated for association with AID, apart from the association of HLA-B*27 with ankylosing spondylitis, it has been difficult to determine additional susceptibility loci independent of the strong linkage disequilibrium (LD) with the HLA class II genes. Recent advances in the statistical analysis of LD and the recruitment of large AID datasets have allowed investigation of the HLA class I and III regions to be re-visited. Association of the HLA class I region, independent of known HLA class II effects, has now been detected for several AIDs, including strong association of HLA-B with type 1 diabetes and HLA-C with multiple sclerosis and Graves' disease. These results provide further evidence of a possible role for bacterial or viral infection and CD8+ T cells in AID onset. The advances being made in determining the primary associations within the HLA region and AIDs will not only increase our understanding of the mechanisms behind disease pathogenesis but may also aid in the development of novel therapeutic targets in the future.
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PMID:The HLA Region and Autoimmune Disease: Associations and Mechanisms of Action. 1941 18

Fulminant type 1 diabetes is a novel subtype characterized by a markedly rapid progression and almost complete destruction of pancreatic beta cells. The number of patients in Japan has been speculated to be 5,000-7,000. A marked decrease of beta cells in addition to alpha cells and mononuclear cell infiltration both in the endocrine and exocrine pancreas are characteristic pathological findings in recent-onset fulminant type 1 diabetes. Laboratory examinations have revealed a high blood glucose level, near normal hemoglobin A1c, ketosis or ketoacidosis, elevation of serum pancreatic exocrine enzymes, and absence of anti-islet autoantibodies such as anti-glutamic acid decarboxylase (GAD) antibody or anti-insulinoma-associated antigen-2 (IA-2) antibody at disease onset. Genetic factors of HLA-DR-DQ, CTLA-4, and HLA-B are associated with this subtype. Both diagnostic criteria for screening and establishing have been announced by the Japan Diabetes Society. In approximately half of fulminant type 1 diabetes, HbA1c was lower than 6.2% at disease onset, indicating that newly proposed diagnostic criteria of diabetes (HbA1c > or = 6.5%) from the joint committee of the American Diabetes Society, the European Association for the Study of Diabetes, and the International Diabetes Federation are not applicable to fulminant type 1 diabetes. In conclusion, all medical practitioners must remember that fulminant type 1 diabetes, an extremely rapidly progressing type of diabetes, does exist, and must pay special attention to avoid overlooking this disease.
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PMID:[Fulminant type 1 diabetes mellitus]. 2040 39

Fulminant type 1 diabetes is defined as a subtype of type 1 diabetes with a remarkably acute onset. A nationwide survey identified that this variant accounts for approximately 20% of acute-onset type 1 diabetic patients in Japan. Recent studies indicate that this is not a minor subtype in other East Asian countries. As genetic factors, we revealed association of HLA-DR-DQ, HLA-B and CTLA-4 to fulminant type 1 diabetes. As an environmental factor, viral infection would contribute to the development of this subtype. Cellular infiltration to islets was detected soon after the onset but not observed 1 month after the onset. Macrophages and T cells were the main components of the infiltrates. Enterovirus RNA and Toll-like receptor-3 expression, a signature of viral infection, was also observed. These findings suggest that viral infection in the susceptible individual might trigger anti-viral immune response and that pancreatic beta cells are rapidly destroyed through the accelerated immune reaction.
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PMID:Fulminant type 1 diabetes--an important subtype in East Asia. 2206 93

Interactions among multiple genes across the genome may contribute to the risks of many complex human diseases. Whole-genome single nucleotide polymorphisms (SNPs) data collected for many thousands of SNP markers from thousands of individuals under the case-control design promise to shed light on our understanding of such interactions. However, nearby SNPs are highly correlated due to linkage disequilibrium (LD) and the number of possible interactions is too large for exhaustive evaluation. We propose a novel Bayesian method for simultaneously partitioning SNPs into LD-blocks and selecting SNPs within blocks that are associated with the disease, either individually or interactively with other SNPs. When applied to homogeneous population data, the method gives posterior probabilities for LD-block boundaries, which not only result in accurate block partitions of SNPs, but also provide measures of partition uncertainty. When applied to case-control data for association mapping, the method implicitly filters out SNP associations created merely by LD with disease loci within the same blocks. Simulation study showed that this approach is more powerful in detecting multi-locus associations than other methods we tested, including one of ours. When applied to the WTCCC type 1 diabetes data, the method identified many previously known T1D associated genes, including PTPN22, CTLA4, MHC, and IL2RA. The method also revealed some interesting two-way associations that are undetected by single SNP methods. Most of the significant associations are located within the MHC region. Our analysis showed that the MHC SNPs form long-distance joint associations over several known recombination hotspots. By controlling the haplotypes of the MHC class II region, we identified additional associations in both MHC class I (HLA-A, HLA-B) and class III regions (BAT1). We also observed significant interactions between genes PRSS16, ZNF184 in the extended MHC region and the MHC class II genes. The proposed method can be broadly applied to the classification problem with correlated discrete covariates.
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PMID:BLOCK-BASED BAYESIAN EPISTASIS ASSOCIATION MAPPING WITH APPLICATION TO WTCCC TYPE 1 DIABETES DATA. 2214 Apr 19

The primary associations of the HLA class II genes, HLA-DRB1 and HLA-DQB1, and the class I genes, HLA-A and HLA-B, with type 1 diabetes (T1D) are well established. However, the role of polymorphism at the HLA-DRB3, HLA-DRB4, and HLA-DRB5 loci remains unclear. In two separate studies, one of 500 subjects and 500 control subjects and one of 366 DRB1*03:01-positive samples from selected multiplex T1D families, we used Roche 454 sequencing with Conexio Genomics ASSIGN ATF 454 HLA genotyping software analysis to analyze sequence variation at these three HLA-DRB loci. Association analyses were performed on the two HLA-DRB loci haplotypes (DRB1-DRB3, -DRB4, or -DRB5). Three common HLA-DRB3 alleles (*01:01, *02:02, *03:01) were observed. DRB1*03:01 haplotypes carrying DRB3*02:02 conferred a higher T1D risk than did DRB1*03:01 haplotypes carrying DRB3*01:01 in DRB1*03:01/*03:01 homozygotes with two DRB3*01:01 alleles (odds ratio [OR] 3.4 [95% CI 1.46-8.09]), compared with those carrying one or two DRB3*02:02 alleles (OR 25.5 [3.43-189.2]) (P = 0.033). For DRB1*03:01/*04:01 heterozygotes, however, the HLA-DRB3 allele did not significantly modify the T1D risk of the DRB1*03:01 haplotype (OR 7.7 for *02:02; 6.8 for *01:01). These observations were confirmed by sequence analysis of HLA-DRB3 exon 2 in a targeted replication study of 281 informative T1D family members and 86 affected family-based association control (AFBAC) haplotypes. The frequency of DRB3*02:02 was 42.9% in the DRB1*03:01/*03:01 patients and 27.6% in the DRB1*03:01/*04 (P = 0.005) compared with 22.6% in AFBAC DRB1*03:01 chromosomes (P = 0.001). Analysis of T1D-associated alleles at other HLA loci (HLA-A, HLA-B, and HLA-DPB1) on DRB1*03:01 haplotypes suggests that DRB3*02:02 on the DRB1*03:01 haplotype can contribute to T1D risk.
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PMID:Next generation sequencing reveals the association of DRB3*02:02 with type 1 diabetes. 2346 45

Disease susceptibility for type 1 diabetes is strongly associated with the inheritance of specific HLA alleles. However, conventional allele frequency analysis can miss HLA associations because many alleles are rare. In addition, disparate alleles that have similar peptide-binding sites, or shared epitopes, can be missed. To identify the HLA shared epitopes associated with diabetes, we analyzed high-resolution genotyping for class I and class II loci. The HLA epitopes most strongly associated with susceptibility for disease were DQB1 A(57), DQA1 V(76), DRB1 H(13), and DRB1 K(71), whereas DPB1 YD(9,57), HLA-B C(67), and HLA-C YY(9,116) were more weakly associated. The HLA epitopes strongly associated with resistance were DQB1 D(57), DQA1 Y(80), DRB1 R(13), and DRB1 A(71). A dominant resistance phenotype was observed for individuals bearing a protective HLA epitope, even in the presence of a susceptibility epitope. In addition, an earlier age of disease onset correlated with significantly greater numbers of susceptibility epitopes and fewer resistance epitopes (P < 0.0001). The prevalence of both DQ and DR susceptibility epitopes was higher in patients than in control subjects and was not exclusively a result of linkage disequilibrium, suggesting that multiple HLA epitopes may work together to increase the risk of developing diabetes.
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PMID:Multiple HLA epitopes contribute to type 1 diabetes susceptibility. 2435 3

The largest contribution of type 1 diabetes mellitus (T1DM) from a single locus comes from several genes located in the major histocompatibility complex on chromosome 6p21. Because DQB1 is the best single genetic marker for T1DM, it is the gene most often used to identify individuals with a high risk of developing disease. As per the data collected from the All India Institute of Medical Sciences, among the human leukocyte antigen (HLA)-DRB1 genes, HLA-DR3 showed strongest association with the disease; however, unlike Caucasians and other populations, DR4 was not significantly increased in these patients. HLA-DR10, 11, 13, and 15 showed a negative association with the disease as they were reduced in these patients. In India, the relative risk of developing T1DM is higher with the DR3-DQ2 haplotypes as compared to DR4-DQ8 haplotypes. Studies have shown that in North India, the relative risk for T1DM is comparatively higher (>30) with the DQ2/DQ8 genotype, but is relatively lower (approximately 18) for the DQ2/DQ2 genotype. In addition, the three sets of HLA-B-DR3 haplotypes, mainly B58-DR3, B50-DR3, and B8-DR3 have shown to have modulated susceptibility for T1DM in India and worldwide. New interventions that will be tested in the future will be conducted through T1DM TrialNet, a collaborative network of clinical centers and experts in diabetes and immunology. These studies will identify unaffected first-degree relatives with beta cell autoantibodies who will be eligible for new interventions.
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PMID:Understanding type 1 diabetes through genetics: Advances and prospects. 2594 48


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