Genetic susceptibility to non-insulin dependent diabetes mellitus and glucose intolerance are located in HLA region.

OBJECTIVES--To test the hypothesis that the genetic susceptibility to non-insulin dependent diabetes mellitus is the same as that to insulin dependent disease and to see whether glucose intolerance is associated with specific HLA haplotypes. DESIGN--Population based study of men in 1989 first tested for glucose tolerance in 1984. HLA haplotypes, including HLA-A, C, B, DR, and DQ, were defined serologically. HLA haplotype data from a population based Finnish study of childhood diabetes were used for predicting non-insulin dependent diabetes and impaired glucose tolerance. SETTING--Two communities in Finland. SUBJECTS--Representative cohort of Finnish men aged 70-89, comprising 98 men with non-insulin dependent diabetes mellitus and a randomly selected group of 74 men, who served as controls, who were tested for glucose tolerance twice within five years. MAIN OUTCOME MEASURES--Non-insulin dependent diabetes, impaired glucose tolerance, blood glucose concentration. RESULTS--Diabetes associated HLA haplotypes were present in 94% (85/90) of diabetic subjects, 79% (27/34) of subjects with impaired glucose tolerance, and only 13% (3/23) of non-diabetic subjects. In this group of elderly men sensitivity of the diabetes associated HLA haplotypes for non-insulin dependent diabetes and impaired glucose tolerance was 90%, specificity 87%, and predictive power 97%. Mean fasting blood glucose concentration was only just significantly higher in men with diabetes associated haplotypes than in men with no such haplotypes, but there was a substantial difference in blood glucose values two hours after glucose loading (10.4 and 6.4 mmol/l in men with diabetes associated HLA haplotypes and men with no such haplotypes, respectively (p < 0.0001)). CONCLUSIONS--These findings support the hypothesis that specific HLA haplotypes exhibit a common genetic determinant for insulin dependent and non-insulin dependent diabetes. Furthermore, HLA is a major genetic determinant of glucose intolerance in elderly Finnish men. The belief that the HLA predisposition to diabetes is specific for insulin dependent diabetes mellitus is largely incorrect.     

HLA DR antigens and susceptibility to insulin-dependent diabetes mellitus.

Two novel analytic methods to evaluate the roles of the HLA alleles of the human major histocompatibility complex in disease predisposition have been formulated and applied to insulin-dependent diabetes mellitus (IDDM). The HLA-DR antigens, as they are presently defined, are shown not to directly predispose individuals to IDDM. This result does not discount the possibility that subdivision of the DR antigens will yield the predisposing agents. In Caucasian populations, after consideration of the predisposing effect of the antigens DR3 and DR4, the protective effect of DR2 in predisposition is demonstrated. Additionally, DR1 and possibly DRw8 exhibit a higher than expected frequency in patients.     

Genetic susceptibility to type 1 diabetes mellitus in humans

Type 1 diabetes mellitus (DM 1A) is an autoimmune disease belonging to the most frequent chronic diseases of the childhood and young adults. DM 1A results from immune-mediated destruction of the insulin-producing beta cells of the pancreas. It is a genetically determined disease and many genes or genetic regions were found to be associated with its induction. In addition to the insulin-dependent diabetes mellitus 1 (IDDM1) gene, which marks the HLA region, and IDDM2 which marks the insulin gene, significant associations of DM 1A to other IDMM genes or genetic regions we reported. We shortly review recent achievements in the field, and the state of current knowledge.     

Genetic analysis of the structure of predisposition to diabetes mellitus. III. Genetic heterogeneity of diabetes mellitus with different ages of onset

The results of genetical-epidemiological analysis of the three conventional forms of diabetes mellitus (DM) differentiated for age-at-onset are presented (the form I - from 0 to 29 y. the form II - from 30 to 59 y. the form III - 60 y. and older). The estimates of heritability of liability to the forms I, II and III of DM were 0.57, 0.70 and 0.65, respectively. It was shown that genetic components of the forms I and II are virtually different: genetic correlation between these forms was rA = 0.216 +/- 0.203, which is statistically insignificant. These data support the hypothesis assuming genetic independence of juvenile and adult forms of DM. On the other hand, the forms II and III were found to have an essential number of genes in common: genetic correlation was rA = 0.495 +/- 0.134, being significant at the 5% level. Thus, the forms II and III of DM are not to be considered as two genetically distinct diseases. The low recurrence risks of the form I for siblings (not more than 3.6%) allow to reject the hypothesis of simple monogenic inheritance of juvenile DM and to propose multifactorial nature of the disease.     

Genetic analysis of the structure of the predisposition to diabetes mellitus. II. The prevalence, morbidity and heritability of diabetes mellitus

Prevalence of diabetes mellitus (D.M.) was estimated in several Moscow districts. The prevalence increases with the age from 0.073 in males and 0.085% in females at the age of 16-19 yrs to 4.9 in males and 6.2% in females at the age of 75 yrs and older. The overall prevalence of D.M. was 1.12%. The morbidity risks have the same patterns of increase: from 0.007 and 0.008% at the age of 0-4 yrs to 1.6 and 2.7% at the age of 75 yrs and older in males and females, respectively. The values of "cumulative" morbidity risk, for the population living long enough, derived from the estimates of age-specific morbidity risks were 6.57 for males and 11.93% for females. The estimate of correlation between first-degree relatives at onset-age of D.M. was 0.307. Accounted for the age-at-onset of the probands and for current ages of siblings, the estimates of recurrence risks, i.e. the probability to develop D.M. for siblings living long enough, were: 27.28 for sisters of the male-probands, 21.59 for sisters of the female-probands, 19.28 for brothers of male-probands and 9.62% for brothers of the female-probands. Thus, the family distribution of D.M., according to the sex of the probands and that of their relatives corresponds to the multifactorial model of inheritance for the diseases with sex-specific thresholds. The estimates of correlation in liability and that of heritability of D.M. calculated from the data on sibs, were 0.284 +/- 0.0351 and 0.568 +/- 0.0702, respectively. The data obtained show that hereditary factors play an essential role in the development of D.M. These results are of a practical interest for genetic counselling, as well as for establishing the preventive measures in the Public Health Service.     

Heterogeneity of non-insulin-dependent diabetes mellitus in HLA types and clinical features: comparison with insulin-dependent diabetes mellitus

We determined HLA types in 110 Japanese patients with non-insulin-dependent diabetes mellitus (NIDDM) and studied the relationship between the HLA phenotypes and clinical features. Sixty-nine patients with insulin-dependent diabetes mellitus (IDDM) and 100 healthy blood donors served as controls. Concerning HLA DR and DQ loci, frequencies of DR4, DRw9 and DQw3.2 were higher, and those of DR2, DRw8, DRw11, DRw12 and DQw1 were lower in patients with IDDM compared than in healthy controls. There were no differences between NIDDM and normal controls in the frequency of a particular HLA DR antigen except for a decreased frequency in DRw11 in the former. The frequency of DQw3.2 antigen in NIDDM was intermediate between IDDM and normal controls. There were some differences between DQw3.2-positive and -negative NIDDM patients in clinical features. Those who showed low C-peptide responses during oral glucose tolerance test were more frequently found among DQw3.2-positive NIDDM patients. These results suggest that Type 1 diabetes mellitus may have a mild clinical course and is found among the Japanese NIDDM population.     

The immunoglobulin heavy-chain variable region in insulin-dependent diabetes mellitus: affected-sib-pair analysis and association studies.

We have analyzed immunoglobulin heavy-chain variable-region (VH) polymorphisms and genetic susceptibility to insulin-dependent diabetes mellitus (IDDM) by using a set of polymorphic loci that span approximately 1,000 kb of the VH region on chromosome 14q32. One hundred one Finnish families with at least two children affected with IDDM were studied. Conventional RFLPs determined by hybridization were used, since no microsatellite repeat markers have been available for this gene region. No evidence for linkage between the VH genes and IDDM could be obtained from haplotype-sharing analysis among the 133 diabetic sib pairs. The frequencies of various VH genotypes were also compared between 101 familial IDDM cases and 114 controls derived from the Finnish background population. The distribution of the genotypes at the VH2-B5 locus was significantly different between these groups (P=.004), the 3.4/3.4 genotype being less common in the IDDM cases. In addition, a different genotype distribution at the VH5-B2 locus was observed in the diabetic subjects (P = .022). When the IDDM cases were stratified by presence or absence of the high-risk HLA-DQB1*0302 allele, no differences in VH genotype frequencies were observed between the 0302-positive and 0302-negative cases. In the transmission test for linkage disequilibrium (TDT), no differences were found between the expected and observed frequencies of the transmitted alleles at the VH2-B5 or VH5-B2 locus. In conclusion, significant differences in VH genotype distributions were observed between the familial IDDM cases and the controls, but the observed associations could not be confirmed by the TDT. Haplotype sharing analysis provided no evidence for genetic linkage between the VH gene region and IDDM.     

Genetic association, post-translational modification, and protein-protein interactions in Type 2 diabetes mellitus

Type 2 diabetes mellitus is a complex disorder with a strong genetic component. Inherited complex disease susceptibility in humans is most commonly associated with single nucleotide polymorphisms. The mechanisms by which this occurs are still poorly understood. Here we focus on analyzing the effect of a set of disease-causing missense variations of the monogenetic form of Type 2 diabetes mellitus and a set of disease-associated nonsynonymous variations in comparison with that of nonsynonymous variations without any experimental evidence for association with any disease. Analysis of different properties such as evolutionary conservation status, solvent accessibility, secondary structure, etc. suggests that disease-causing variations are associated with extreme changes in the value of the parameters relating to evolutionary conservation and/or protein stability. Disease-associated variations are rather moderately conserved and have a milder effect on protein function and stability. The majority of the genes harboring these variations are clustered in or near the insulin signaling network. Most of these variations are identified as potential sites for post-translational modifications; certain predictions have already reported experimental evidence. Overall our results indicate that Type 2 diabetes mellitus may result from a large number of single nucleotide polymorphisms that impair modular domain function and post-translational modifications involved in signaling. Our emphasis is more on conserved corresponding residues than the variation alone. We believe that the approach of considering a stretch of peptide sequence involving a polymorphism would be a better method of defining the role of the polymorphism in the manifestation of this disease. Because most of the variations associated with the disease are rare, we hypothesize that this disease is a "mosaic model" of interaction between a large number of rare alleles and a small number of common alleles along with the environment, which is little contrary to the existing common disease common variant model.     

Genetic analysis of the structure of the predisposition to diabetes mellitus. I. Genetic epidemiological approaches to an analysis of age-dependent multifactorial diseases

The statistical methods for genetic analysis of multifactorial diseases (MFD) with variable age-at-onset are developed. It is emphasized that the index numbers used in the genetical-epidemiological studies, such as frequency of MFD in the population (qg--incidence) and that among family members (PR), should be independent on the demographic structure of both the population and the families. The mathematical grounds for the estimating methods as well as biological meaning for such index numbers are given. The approach suggested will be used later in analysis of the structure of predisposition to diabetes mellitus.     

Genetic analysis of HLA in the U.S. Schmiedenleut Hutterites.

The Hutterites are an Anabaptist population, highly inbred, with large family sizes and extensively documented pedigrees. As part of genetic-epidemiologic studies of the impact of HLA on fertility, HLA-A, -B, -C, -DR, and -DQ typing was performed on a total of 650 Schmiedenleut Hutterities in South Dakota. An extraordinary degree of homogeneity was found. HLA-A1, -A2, -A3, -A24, and -A26 accounted for 83%, HLA-B8, -B27, -B35, -B51, -Bw60, and -Bw62 for 75%, and HLA-DR1, -DR2, -DR3, and -DR4 for 66% of the antigens at the respective HLA-A, -B, and -DR loci. All Hutterites characterized for HLA were descendants of no more than 78 ancestors. However, family analysis identified only 45 unique HLA haplotypes thought to reflect the original gene pool. Eight haplotypes were particularly frequent, accounting for nearly 50% of all observed haplotypes; four of these were consistent with a European ancestry. Coefficients measuring linkage disequilibrium were computed from haplotypes identified by family analysis. Overall, HLA analysis portrayed the Schmiedenleut Hutterities as a homogeneous and unique population, with disequilibrium among particular alleles and a spectrum of common and uncommon European haplotypes.     

Heterozygous expression of insulin-dependent diabetes mellitus (IDDM) determinants in the HLA system.

HLA phenotypes of cases with insulin-dependent diabetes mellitus (IDDM) and identity by descent of HLA haplotypes in affected sib-pairs support an intermediate model in which morbid risk is increased by one HLA-linked IDDM determinant, and greatly increased by two determinants, which may be qualitatively different in DR3 and DR4 haplotypes. Linkage analysis allowing for gametic disequilibrium reveals no recombination in pedigrees with a DR3/DR4 propositus, but spurious recombination in the remaining pedigrees. This evidence favors interaction of unlinked IDDM determinants to produce affection in a small proportion of heterozygotes for an HLA-linked determinant. Partition of data by HLA type of the propositus (ideally by DR and the complement types jointly) is a powerful method to resolve etiological heterogeneity for HLA-associated diseases.     

The role of HLA class II genes in insulin-dependent diabetes mellitus: molecular analysis of 180 Caucasian,multiplex families.

We report here our analysis of HLA class II alleles in 180 Caucasian nuclear families with at least two children with insulin-dependent diabetes mellitus (IDDM). DRB1, DQA1, DQB1, and DPB1 genotypes were determined with PCR/sequence-specific oligonucleotide probe typing methods. The data allowed unambiguous determination of four-locus haplotypes in all but three of the families. Consistent with other studies, our data indicate an increase in DR3/DR4, DR3/DR3, and DR4/DR4 genotypes in patients compared to controls. In addition, we found an increase in DR1/DR4, DR1/DR3, and DR4/DR8 genotypes. While the frequency of DQB1*0302 on DR4 haplotypes is dramatically increased in DR3/DR4 patients, DR4 haplotypes in DR1/DR4 patients exhibit frequencies of DQB1*0302 and DQB1*0301 more closely resembling those in control populations. The protective effect of DR2 is evident in this data set and is limited to the common DRB1*1501-DQB1*0602 haplotype. Most DR2+ patients carry the less common DR2 haplotype DRB1*1601-DQB1*0502, which is not decreased in patients relative to controls. DPB1 also appears to play a role in disease susceptibility. DPB1*0301 is increased in patients (P < .001) and may contribute to the disease risk of a number of different DR-DQ haplotypes. DPB1*0101, found almost exclusively on DR3 haplotypes in patients, is slightly increased, and maternal transmissions of DRB1*0301-DPB1*0101 haplotypes to affected children occur twice as frequently as do paternal transmissions. Transmissions of DR3 haplotypes carrying other DPB1 alleles occur at approximately equal maternal and paternal frequencies. The complex, multigenic nature of HLA class II-associated IDDM susceptibility is evident from these data.     

HLA class II SNP interactions and the association with type 1 diabetes mellitus in Bengali speaking patients of Eastern India

Background

Several studies have demonstrated a fundamental role for the HLA in the susceptibility of, or protection to, type 1 diabetes mellitus (T1DM). However, this has not been adequately studied in Asian Indian populations. To assess the frequency of HLA class II (DPA1, DPB1, DQA1, DQB1 and DRB1) associated to susceptibility or protection toT1DM in a Bengali population of India with diabetes.

Results

Single nucleotide polymorphism study. The HLA genotyping was performed by a polymerase chain reaction followed by their HLA-DP, DQ, and DRB1 genotypes and haplotypes by sequencing method. The results are studied by Plink software. The χ² tests were used for the inferential statistics. To our knowledge, this study is the first of a kind which has attempted to check the HLA association with T1DM by SNPs analysis. The study recruited 151 patients with T1DM and same number of ethno-linguistic, sex matched non-diabetic controls. The present study found a significant SNP rs7990 of HLA-DQA1 (p = 0.009) negative correlation, again indicating that risk from HLA is considerably more with T1DM.

Conclusions

This study demonstrates that the HLA class-II alleles play a major role in genetic basis of T1DM.     

Genetic considerations on association between HLA and disease

Summary Blood specimens from a random sample of 981 South African Negroid females were typed electrophoretically inter alia for their G-6-PD phenotypes. The allele frequency for Gd^B and Gd^nonB was found to be 0.8126 and 0.1874 respectively. Calculating the number of individuals expected for each phenotypic class, a highly significant deviation from the Hardy-Weinberg equilibrium became manifest, i.e. there was a deficit of 24.6% of heterozygotes and an excess of 12.3% of each of the two classes of homozygotes.Several possible reasons for this discrepancy e.g. the effects of pooling sub-samples, selection and misclassifications due to insufficient staining were examined and were found not to be likely explanations for the observed phenomenon. Instead, the result is interpreted as due to only 3–4 stem cells which give rise to the haematopoetic system in man.Part of this work was presented at the biennial Congress of the Deutsche Gesellschaft für Anthropologie und Humangenetik held in Vienna, September 22–25, 1975Supported by a research fellowship (1975/76) granted by the Alexander von Humboldt-Stiftung, Bonn-Bad GodesbergSupported by the Deutsche Forschungsgemeinschaft (DFG), Bonn-Bad Godesberg     

Genetic analysis of the LEW.1AR1-iddm rat: an animal model for spontaneous diabetes mellitus

The LEW.1AR1-iddm/Ztm rat is a new animal model of type 1 diabetes mellitus, which shows an autosomal recessive mode of inheritance for the diabetes-inducing gene. The aim of this study was to define predisposing loci of the diabetic syndrome by linkage analysis using microsatellite markers. A backcross population of 218 rats (BN × LEW.1AR1-iddm) × LEW.1AR1-iddm was analyzed using 157 polymorphic microsatellite markers covering the entire genome. Three genomic regions showed a significant linkage to the diabetic syndrome. The first susceptibility locus on rat Chromosome (RNO) 1 (LOD score 4.13) mapped to the region 1q51–55, which codes for potential candidate genes like Ins1 and Nkx2-3. The second susceptibility locus was also localized on RNO1 in the centromeric region 1p11 (LOD score 2.7) encompassing the Sod2 gene. The third quantitative trait loci (LOD score 2.97) was located on RNO20 within the major histocompatibility complex region. Comparative mapping revealed that the homologous regions in the human genome contain the IDDM loci 1, 5, 8, and 17. The identification of diabetes susceptibility regions of the genetically uniform LEW.1AR1-iddm rat strain will pave the way toward a detailed characterization of the loci conferring diabetes development as well as their functional relevance for the pathogenesis of type 1 diabetes mellitus.