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)

Our knowledge of the genetics of insulin dependent diabetes (IDDM), and in particular the HLA system, has gained considerable expansion thanks to the application of molecular biology. The genetic susceptibility to the disease is linked to the HLA region, particularly at DQ-alpha and DQ-beta chain genes. Particular amino acid other than aspartic acid in position 57 of the DQ beta chain and the presence of an arginine in position 52 of the DQ alpha chain and to how these markers can be used to identify subjects at risk for developing IDDM. The identification of such subjects may be useful for the development of strategies aimed to prevent the disease and in addition may offer a new insight into population screening.
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PMID:The HLA system and insulin dependent diabetes: recent findings and prospects for disease prediction. 128 13

In this study we report, for the first time, the molecular analysis of HLA-DR and DQ gene frequencies in a large cohort of well-characterized type 1 (insulin-dependent) diabetes mellitus (IDDM) patients (n = 72), and ethnically matched controls (n = 59) collected in sub-Saharan Africa. High molecular mass DNA was prepared and analysed in Southern blots and by oligonucleotide typing. We have shown a strong positive association between IDDM and the Asp 57- DQB1 allele *0201 (DQw2). A rare DR4, DQw2 haplotype was also identified at high frequency in the IDDM cohort. We can now confirm that the association between Asp 57- DQB1 alleles and IDDM, previously reported in ethnically diverse cohorts collected in Western Europe, North America, and South Asia, is also present in an IDDM cohort collected in Africa.
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PMID:Identification of genetic susceptibility loci for insulin-dependent diabetes in Sudan. 135 6

Major determinants of susceptibility to Type 1 (insulin-dependent) diabetes (IDDM) have been mapped to the HLA complex, near to or identical with genes encoding class II molecules. The association of IDDM with HLA-DR3 and/or DR4 antigens and the highest risk for DR3/4 heterozygotes suggest a synergistic effect of the two haplotypes. The characterization at the molecular level of the class II region has provided evidence that DQ rather than DR determinants may primarily influence the disease. In caucasians the susceptibility strongly correlates with the absence of aspartic acid at position 57 on the DQ beta chain and/or the presence of arginine at position 52 on the DQ alpha chain. The formation of a putative DQ susceptibility molecule (DQ alpha Arg52+, DQ beta Asp57-) accounts best for the disease associations when trans-complementation between alpha and beta chains encoded by different haplotypes is postulated to explain the excess of heterozygotes. Observations in other populations and in animal models indicate, however, that other residues on DQ alpha and beta chains, other class II (DR beta) molecules and non-HLA linked genes also contribute to the susceptibility. The mechanism(s) by which susceptibility determinants influence IDDM is not known. It is probably in relation with the role of class II molecules in the antigen presentation to T lymphocytes.
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PMID:[The role of the HLA system in the genetics of Type I diabetes mellitus]. 145 12

Some insulin-dependent diabetic patients present with auto-immune diseases involving extra pancreatic tissues (type 1b diabetes mellitus). The genetic specificity of this syndrome, as opposed to insulin dependent diabetes mellitus (IDDM) free of such associations (Type 1a IDDM) is not clearly established. We have analyzed the HLA-DQB1 and DQA1, loci, after PCR amplification of genomic DNA, in 44 Type 1b IDDM patients, 78 Type 1a IDDM patients and 105 control subjects. No essential difference in HLA-DQ profiles appeared between Type 1b and Type 1a IDDM patients. Both diabetic groups displayed a significant enrichment in DQB1 alleles negative for aspartate at position 57 (Type 1b: 83%; Type 1a: 89%; controls 48%; p < 0.001 vs both patient groups) and in DQB1 Asp 57 negative homozygosity: 71% of Type 1b; 80% of Type 1a; 25% of controls (p < 0.01). This enrichment in DQB1 Asp 57 negative alleles was accounted for by DQB1* 0201 in the Type 1b group, and by DQB1 % 0201 and 0302 in the Type 1a patients. Conversely, alleles DQB1* 0602 and 0301 (DQB1 Asp 57 positive) were protective. Both diabetic groups also displayed a significant enrichment in DQA1 alleles positives for arginine at position 52 (65% of Type 1b; 76% of Type 1a; 50% of control subjects; p < 0.01 and 0.001, respectively, vs controls), and in DQA1 Arg 52 positive homozygotes (48% of Type 1b, 58% of Type 1a, 22% of control subjects; p < 0.01). All differences between diabetic groups and the control group were more pronounced in the case of Type 1a than of Type 1b patients. The HLA-DQ genes shared by Type 1a and Type 1b patients must therefore be closely associated with islet autoimmunity. Genetic differences between Type 1a and Type 1b syndromes, if any, must be investigated in other MHC and non-MHC regions of the genome.
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PMID:Similarity of HLA-DQ profiles in adult-onset type 1 insulin-dependent diabetic patients with and without extra-pancreatic auto-immune disease. 145 19

Genetic susceptibility alleles have been identified at the DQ HLA region. The aim of the present study was to confirm the value of these markers, and to evaluate the respective weight in the risk of the different alleles at the DQA1 and DQB1 levels, identified by restriction mapping after polymerase chain reaction on exon 2. A significant enrichment in DQB1 alleles encoding for an aminoacid different from Aspartic acid at position 57 (NA) was observed in diabetic (n = 213) in comparison to control (n = 93) children (94% vs 52%; p < 10(-8)). Not all the given NA/NA allelic combinations were equally and positively associated to the disease. Homozygous "Ala/Ala" combinations carried the highest relative risk (OR = 12.3; p < 10(-8)), and among them, the *0201/*0302 genotype was more positively associated to type 1 diabetes (OR = 66; p < 10(-8)). A significant enrichment in DQA1 alleles encoding for Arginine at position 52 in diabetic children was also observed (82% vs 40%; p < 10(-8)). The *0301/*0501 (Arg/Arg) genotype was significantly associated to Type 1 diabetes (OR = 16.2; p < 10(-4)). The highest risk was carried by the whole genotype, a result which could be expected from the known linkage desequilibrium between HLA-DQA1 and DQB1, DRB1 loci. The frequency of Ala DQB1 alleles was low in the background non-at-risk population, although the incidence of the disease is low in our country.
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PMID:[Respective weight of genotypes DQA1 and DQB1 associated with insulin-dependent diabetes in French children]. 145 18

A significant increase in the prevalence of selective IgA deficiency has been observed in patients with autoimmune disorders such as systemic lupus erythematosus and rheumatoid arthritis. Insulin-dependent diabetes mellitus (IDDM) is an autoimmune disease and susceptibility to both IDDM and IgA deficiency is associated with HLA DQB1 alleles encoding non-Asp amino acids at position 57. In order to assess whether the prevalence of selective IgA deficiency is increased in IDDM, we have screened a homogeneous series of adult patients with IDDM for selective IgA deficiency. One patient (1:261) was found to have a selective IgA deficiency. The prevalence of selective IgA deficiency among adult French blood donors is 1:1400. Thus, although IDDM and selective IgA deficiency are both associated with the presence of non-Asp amino acids at position 57 of the HLA DQ beta chain, the frequency of this immunodeficiency in adult IDDM patients is not significantly increased.
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PMID:The prevalence of selective IgA deficiency in type 1 diabetes mellitus. 152 Apr 83

Insulin-dependent diabetes mellitus (IDDM) in whites is strongly associated with particular HLA-DQ alpha beta heterodimers composed of a DQ alpha chain with an arginine at residue 52 (Arg52+) combined to a DQ beta chain lacking an aspartic acid at residue 57 (Asp57-). With the aim of confirming this association, clarifying which heterodimers account for the highest risk of IDDM and explaining the excess risk of DR3-DQw2/DR4-DQw8, 115 unrelated white IDDM patients and 108 unrelated healthy nondiabetic control subjects were studied. With polymerase chain reaction and sequence-specific oligonucleotide probes, both patients and control subjects were typed for their HLA-DQA1 and DQB1 alleles and their DQA1-DQB1 haplotype and genotype frequencies were compared. Four major findings emerged from our analysis. 1) Arg52+ DQ alpha/Asp57- DQ beta heterodimers, formed in cis and/or in trans, are strongly associated with susceptibility to IDDM; 97% of patients and 46% of control subjects had at least one such susceptibility heterodimer (relative risk [RR] 32, confidence interval [Cl] 14.25-71.86, P less than 10(-7). 2) The degree of disease susceptibility depends on the number of such DQ heterodimers that a subject can express according to his or her DQA1-DQB1 genotype. The highest RR was observed in patients with four susceptibility DQ heterodimers (RR 41, Cl 17.05-95.9). 3) Only part of the susceptibility DQ heterodimers were significantly increased in patients, conferring IDDM susceptibility of different strength. The strongest association was with the DQA1*0501-DQB1*0302 combination formed in trans position (RR 35.2, CI 12.88-96.78, P less than 10(-7).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Dose effect of cis- and trans-encoded HLA-DQ alpha beta heterodimers in IDDM susceptibility. 155 98

In this study we report for the first time, the molecular analysis of HLA-DR and -DQ gene frequencies in a large cohort of well characterized type 1 (insulin-dependent) diabetes mellitus (IDDM) patients (n = 72), and ethnically matched controls (n = 59) collected in sub-Saharan Africa. High molecular mass DNA was prepared and analyzed in Southern blots with DRB1, DQA1, and DQB1 probes. By identifying DR and DQ allele-specific restriction fragment length polymorphisms (RFLPs), we have shown a strong positive association between IDDM and the Asp 57- DQB1 allele *0201 (DQw2). A rare DR4, DQw2 haplotype was also identified at high frequency in the IDDM cohort. We can now confirm that the association between Asp 57-DQB1 alleles and IDDM, previously reported in ethnically diverse cohorts collected in Western Europe, North America, and South Asia, is also present in an IDDM cohort collected in Africa.
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PMID:Analysis of HLA-DR and -DQ gene polymorphisms in Sudanese patients with type 1 (insulin-dependent) diabetes. 168 74

Some alleles of the HLA-DQB1 and DQA1 loci are preferentially associated with susceptibility to type 1 (insulin-dependent) diabetes mellitus (IDDM). Analysis of the HLA-DQ genetic profile may therefore become important for the screening of subjects at risk of IDDM. However ethnic variations in the genetic profile can occur and require background knowledge of the HLA-DQ allelic distribution before screening campaigns. In the present work, HLA-DQA1 and DQB1 genes have been analyzed, after PCR amplification of the genomic DNA, in French and Algerian control subjects (a total of 148) and diabetic patients (a total of 107). Allelic distributions have been investigated in view of a) possible inter-ethnic differences; b) identification of risk and protective alleles and c) the prevalence of DQB1 aspartate 57 negative and DQA1 arginine 52 positive alleles in control and diabetic groups. The DQB1 allelic distribution was similar in both control groups; alleles negative for aspartate at position 57 were 48% in French and 50% in Algerian. In both diabetic groups, the prevalence of alleles negative for aspartate at position 57 was significantly higher: 91% (French) and 81% (Algerian) (p less than 0.001). A majority of patients were homozygote for DQB1 Asp 57 negativity: 83% (French) and 63% (Algerian). The highest relative risk was associated with HLA-DQB1 0201/0302 heterozygosity. The HLA-DQA1 allelic distribution was also similar in French and Algerian controls. Alleles positive for arginine (ARG+) at position 52 were 50% (French) and 57% (Algerian) of controls. In both diabetic groups the prevalence of alleles positive for arginine at position 52 was significantly higher: 78% (French) and 84% (Algerian).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:HLA-DQA1 and DQB1 alleles in French and Algerian type 1 diabetic subjects. 168 68

1. In no ethnic group is the overall association between systemic sclerosis and the MHC strong enough for direct clinical use. MHC associations do support the classification of the disease into limited cutaneous systemic sclerosis and diffuse cutaneous systemic sclerosis. 2. Indications are that associations between specific subsets of patients with systemic sclerosis and genetic markers will assume greater importance both diagnostically and prognostically. The group with lung fibrosis look prime candidates, for example. 3. Genetic markers are useful means of relating chemically induced systemic sclerosis like disorders with the classical disease. Vinyl chloride disease provides an example. 4. Evidence is emerging of strong associations between certain genetic markers and autoantibody production; a similar story has emerged in systemic lupus erythematosus. We believe that, eventually, genetic tests will be used to influence treatment in at least a subset of patients with systemic sclerosis but that a dramatic breakthrough will not be made until we know how the genetics of the disease relate to the primary biochemical disease characteristic--that is, the overproduction of collagen. In this respect it has been suggested that the 5' flanking DNA of dermal collagen genes is particularly susceptible to the action of Scl-70 (topoisomerase I). A problem is how to tie this and the other observations discussed above together. The association of autoantibodies with topoisomerase I provides a tentative link between the MHC and collagen gene expression. Although the role and reason for anti-Scl-70 in systemic sclerosis is unknown, humoral autoimmunity, at least in systemic lupus erythematosus, seems to be strongly dependent on specific HLA genes. With an understanding of the function of MHC products at the molecular level, HLA and disease associations can now be analysed on a mechanistic level. For insulin dependent diabetes mellitus it has been shown that the MHC determined susceptibility to the disease is conferred by neutral residues (Val, Ser, Ala), at position 57 of the DQ beta chain, while Asp at this position correlates with resistance. A similar phenomenon has been described in rheumatoid arthritis. Although DR4 in general is associated with rheumatoid arthritis, it is heterogeneous, but a subtype of DR4 which is characterised by positively charged residues at positions 70 and 71 of the beta chains is not found in patients with rheumatoid arthritis (Wordsworth B P et al, unpublished data). A similar approach applied to the study of systemic sclerosis is likely to be similarly rewarding. The precise subtyping of the class II genes and the characterisation of their associated haplotypes is therefore required for a complete understanding of the contribution of the MHC to the disease. Additional genes linked to the MHC must not be overlooked, and are relevant to associations of haplotypes with the disease. Of particular interest are the recent reports of a new class of proteins, which are determined by genes in the MHC and which are considered to play a part in the assembly of the antigen peptide/MHC molecule complex.
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PMID:Major histocompatibility complex class II genes and systemic sclerosis. 175 Jul 98


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