Heterozygosity for MICA5.0/MICA5.1 and HLA-DR3-DQ2/DR4-DQ8 are independent genetic risk factors for latent autoimmune diabetes in adults

Major histocompatibility complex class I chain-related gene A (MICA) encodes polymorphic, stress-inducible antigens recognized by gammadelta T cells within the intestinal epithelium. MICA microsatellite polymorphism has been implicated to be related to different autoimmune diseases. Ninety-eight patients with type 1 diabetes (median age, 35 years; range, 9-89 years and 51 patients with latent autoimmune diabetes (LADA; median age, 48 years; range, 19-79 years) were compared with 113 healthy control patients (median age, 35 years; range, 19-65 years) to study the importance of MICA-microsatellite polymorphism and HLA-DR-DQ as genetic risk factors for diabetes. The different factors were compared univariately and by logistic regression analysis. In the logistic regression model, heterozygosity for MICA5.0/5.1 was a significant risk factor for LADA (odds ratio [OR] = 12; 95% confidence interval [95%CI], 2.5-59) as well as heterozygosity for HLA-DR3-DQ2/DR4-DQ8 (OR = 15; 95%CI, 2.7-84). None of the MICA polymorphisms were related to type 1 diabetes. Heterozygosity for HLA-DR3-DQ2/DR4-DQ8 was a risk factor for type 1 diabetes (OR = 14; 95%CI, 2.9-66) as well as DR4-DQ8/x (OR = 2.8; 95%CI, 1.4-5.9). HLA-DR15-DQ6 was protective for type 1 diabetes (OR = 0.12; 95%CI, 0.015-0.96). We concluded that both heterozygosity for MICA5.0/5.1 and HLA-DR3-DQ2/DR4-DQ8 are separate risk factors for LADA, but that heterozygosity for HLA-DR3-DQ2/DR4-DQ8 and DR4-DQ8 alone are most important for type 1 diabetes.     

Different HLA-DR-DQ and MHC class I chain-related gene A (MICA) genotypes in autoimmune and nonautoimmune gestational diabetes in a Swedish population

The genetic susceptibility for gestational diabetes (GDM) was estimated by comparisons of genotypes within human leukocyte antigen (HLA) and major histocompatibility complex class I chain-related gene A (MICA) in 199 women with GDM and 213 healthy women. At least one of ICA, glutamic acid decarboxylase antibodies, or islet cell antigen-2 antibodies/tyrosine phosphatase antibodies was found in 6.0% (12/199) of women with GDM and were considered as autoimmune GDM, whereas the remaining 187 were considered as nonautoimmune GDM. HLA genotyping was done with polymerase chain reaction and sequence-specific oligonucleotides. MICA polymorphism was determined with polymerase chain reaction and fragment size determination. HLA-DR3-DQ2/x or DR4-DQ8/x and MICA5.0/5.1 were more frequent in autoimmune GDM compared with controls; 92% versus 46% and 42% versus 13% and conferred increased risk (odds ratio [OR] = 13; 95% confidence interval [CI] 1.7–104) and (OR = 4.7; 95%CI 1.4–16). Four other genotypes were more frequent in nonautoimmune GDM compared with controls: HLA-DR7-DQ2/y, 24% versus 14%; DR9-DQ9/y, 9.6% versus 1.9%; DR14-DQ5/y, 7.5% versus 0.94%; and MICA5.0/z, 24% versus 13% and gave increased risk: OR = 2.0; 95%CI 1.2–3.4, OR = 5.6; 95%CI 1.8–17, OR = 8.5; 95%CI 1.9–38, and OR = 2.0; 95%CI 1.2–3.4, respectively. We concluded that autoimmune diabetes with onset during pregnancy is associated with the type 1 diabetes–associated genotypes and also with MICA5.0/5.1, whereas DR7-DQ2/y, DR9-DQ9/y, DR14-DQ5/y, and MICA5.0/z are risk factors for nonautoimmune GDM.     

Homozygosity for Premature Stop Codon of the MHC Class I Chain-Related Gene A (MIC-A) Is Associated with Early Activation of Islet Autoimmunity of DR3/4-DQ2/8 High Risk DAISY Relatives

We hypothesized that homozygosity for the major histocompatibility complex (MHC) class I chain-related gene A (MIC-A)5.1 allele with premature stop codon would increase diabetes risk of individuals followed from infancy in the DAISY study (Diabetes Autoimmunity Study in the young). Forty five percent (10/22) of relatives (siblings and offspring cohort, SOC) who developed anti-islet autoantibodies were MIC-A5.1/5.1 homozygous. Of SOC individuals without autoantibodies, 12/58 (19%, p = 0.02) were MIC-A5.1 homozygous. By life table analysis of expression of autoantibodies, DR3-DQ2/ DR4-DQ8 more than 50% of MIC-A5.1 homozygous children became autoantibody positive by 7 years of age, compared to delayed development of autoantibodies for non-MIC-A5.1/5.1 DR3-DQ2/ DR4-DQ8 children (p = 0.005). For DR3-DQ2/DR4-DQ8 nonrelatives, the risk of activating anti-islet autoimmunity remained low even with MIC-A5.1 homozygosity suggesting that there are additional factors contributing to the marked risk of relatives compared to the general population with the DR3-DQ2/DR4-DQ8 genotype.     

Tumor necrosis factor-associated susceptibility to type 1 diabetes is caused by linkage disequilibrium with HLA-DR3 haplotypes

Tumor necrosis factor-α (TNF-α) is an important proinflammatory cytokine involved in the pathogenesis of autoimmune type 1 diabetes (T1D). The TNF gene locus is located in the major histocompatibility complex (MHC) class III region and its genetic polymorphisms have been reported to be associated with T1D. However, it is not clear whether these associations are primary or caused by their linkage disequilibrium with other predisposing genes within the MHC. We have tested 2 TNF-α single nucleotide polymorphisms at positions -308G/A and -238G/A in the 5' untranslated region and a (GT)n microsatellite TNFa in the North Indian healthy population and T1D patients with known HLA-A-B-DR-DQ haplotypes. The allele frequencies of TNFa5, -308A, and -238G were determined to be significantly increased among patients compared with controls. Although the observed positive association of -238G was caused by its presence on all 3 DR3(+) groups, namely, B8-DR3-DQ2, B50-DR3-DQ2, and B58-DR3-DQ2 haplotypes associated with T1D in this population, the increase of the -308A allele was caused by its association with the latter 2 haplotypes. On the other hand, TNF -308G occurred on B8-DR3 haplotypes along with -238G and TNFa5 alleles, particularly in T1D patients with late disease onset (at >20 years of age). These results indicate that TNF associations with T1D are caused by their linkage disequilibrium with specific HLA-DR3-DQ2 haplotypes in the Indian population. Because polymorphisms in the promoter region regulate TNF expression levels (e.g., -308A), they retain crucial immunological significance in the development of T1D and its management.     

High-risk genotypes HLA-DR3-DQ2/DR3-DQ2 and DR3-DQ2/DR4-DQ8 in co-occurrence of type 1 diabetes and celiac disease

Shared susceptibility alleles in the HLA region contribute to the co-existence of type 1 diabetes (T1D) and celiac disease (CD). The aim of our study was to identify HLA genotype variations that influence co-occurrence of T1D and CD (T1D?+?CD) and the order of their onset. Totally 244 patients, 67 with T1D, 68 with CD and 69 with T1D?+?CD, (split into “T1D first” and “CD first”), were analyzed. Control group consisted of 130 healthy unrelated individuals. Two-tailed Fisher’s exact test was used for statistical analysis. The genetic background of Slovenian CD patients resembled more northern than southern European populations with DR3-DQ2/DR3-DQ2 (odds ratio [OR]?=?19.68) conferring the highest risk. The T1D?+?CD was associated with DR3-DQ2/DR3-DQ2 (OR?=?45.53) and even more with DR3-DQ2/DR4-DQ8 (OR?=?93.76). DR3-DQ2/DR7-DQ2 played a neutral role in susceptibility for T1D?+?CD. The order of the onset of T1D or CD in patients with co-occurring diseases was not influenced by HLA risk genotype profile. DR3-DQ2/DR3-DQ2 was associated with an increased risk for developing CD in patients with T1D, whereas patients with CD carrying DR3-DQ2/DR4-DQ8 were at higher risk for developing T1D. In addition to other genetic factors including HLA class I alleles present on DR3-DQ2 extended haplotype, the second extended haplotype may moderate the risk for T1D?+?CD conferred by DR3-DQ2. Our results suggested that individuals carrying high-risk genotypes DR3-DQ2/DR3-DQ2 or DR3-DQ2/DR4-DQ8 would more likely develop both T1D and CD than either disease alone.     

Association of pulmonar tuberculosis with HLA system antigens in Northeastern Mexico

BACKGROUND: Genetic susceptibility to pulmonary tuberculosis (PTb) has been associated with the HLA (Antigens of the Human Leukocytes) system of the MHC (Major Histocompatibility Complex), mainly with HLA-DR and-DQ antigens. Based on this assumption we carried out a case control study to determine the association of PTb with the HLA-DR and-DQ antigens among a sample of patients attending a medical unit belonging to the Mexican Social Security System (IMSS). METHODS: HLA system phenotypes from cases (n=50) and controls (n=417), were defined serologically using a complement dependent microlymphocytotoxic assay. B lymphocytes were obtained using immunobeads. The allele and haplotype frequencies were determined using the Arlequin version 3.01 computer software. Relative risk (RR) was calculated with the Epimax Table Calculator. RESULTS: The alelles HLA-DR11(5), -DR16(2) and -DQ7(3) and haplotypes /DR11(5)-DQ7(3), /DR14(6)-DQS(1) and /DR16(2)-DQ7(3) had a higher frequency in cases than in controls (RR>1, p<0.05). The HLA-DR17(3) and DQ8(3) alelles and /DR17(3)-DQ2 and /DR4-DQ8(3) haplotypes had a higher frequency among controls than among cases (RR<1, p<.05). CONCLUSIONS: These results indicate an association between PTb with the HLA-DR and -DQ antigens in a Mexican sample. Our results are similar to those found in the international literature.     

HLA class II associations with Type 1 diabetes mellitus: a multivariate approach

The association of HLA class II phenotype with the development of insulin-dependent (Type 1) diabetes mellitus (IDDM) is well established but the contribution of the various HLA-DR and -DQ alleles and haplotypes to disease predisposition is not fully understood. We have determined haplotype and genotype odds ratios, and further employed multivariate tree analysis to explore the contribution of individual HLA-DRDQ haplotypes to the genetic risk for developing IDDM in the Dutch population. Next to haplotype and genotype odds ratios, multivariate tree analysis techniques provide overall risk calculations for each modeled parameter, and offer insight in the interaction of the model parameters via tree-shaped reports, in which subsequent stratifications on the data can easily be followed. We compared 206 Dutch IDDM patients with 840 serologically typed random healthy unrelated Dutch Caucasoid controls. The multivariate tree analysis showed that the HLA-DR7DQ9 and DR15DQ6 haplotype were strongly associated with disease protection (OR = 0.04, P = 0.0003, and OR = 0.07, P < or = 0.0001, respectively). The highest ORs were found for the DR4DQ8/DR8DQ4 genotype (OR = 21.04, P = 0.001), followed by DR4DQ8/DR17DQ2 (OR = 12.45, P < 0.0001) and DR9DQ9/DR17DQ2 (OR = 10.87, P = 0.02). DR4DQ8 homozygous and DR17DQ2 homozygous individuals have a disease OR of 9.0 and 3.0 (P = 0.01 and 0.03), respectively. In conclusion, the results from haplotype, genotype, and tree analyses provide insight into the disease associations for combinations of HLA-DRDQ haplotypes. We confirm that the DR9DQ9/DR17DQ2 genotype is associated with susceptibility in the Dutch population, which has previously been noticed as a HLA risk genotypes in Asian populations only.     

Differences in the genetic background of latent autoimmune diabetes in adults (LADA) and type 1 diabetes mellitus

OBJECTIVES: According to the recent classification of diabetes mellitus the Latent Autoimmune Diabetes in Adults (LADA) belongs to the group of type 1 autoimmune diabetes, as a slowly progressive form. Our aim was to determine (i) the prevalence of HLA-DRB1 and DQB1 genotypes, and (ii) to determine the tumor necrosis factor (TNF) alpha promoter polymorphism at position -308 (the G-->A substitution, designated the TNF2 allele) in patients with type 1 diabetes and with LADA compared with the healthy population. METHODS: The major histocompatibility complex (MHC) II genotypes and the TNF alpha promoter polymorphism were determined by PCR method. We examined 69 type 1 diabetic and 42 LADA patients. As control samples of 336 cadaver kidney donors and 138 volunteers were used. RESULTS: Both type 1 diabetes mellitus and LADA were positively associated with the DRB1*04-DQB1*0302 (DR4/DQ8) haplotype (P=0.00001, and P=0.0005, respectively), and negatively associated with the DRB1*11-DQB1*0301 (DR11/DQ7) haplotype (P=0.00006, and P=0.007, respectively) compared with control population. There were differences between the two disease entities in the frequency of the DRB1*03-DQB1*02 (DR3/DQ2) haplotype (P=0.00008 vs. P=0.177) compared with control group. The presence of the TNF2 allele was significantly lower in LADA than type I diabetes (P=0.022) or control group (P=0.017). CONCLUSION: Our findings indicate that there are marked differences in the genetic background of type 1 diabetes and LADA. The low presence of TNF2 allele (known to be associated with high amount of TNF alpha production) in LADA could be one of the factors responsible for the relatively slow progression.     

HLA-DR,HLA-DQB1 and PTPN22 gene polymorphism: association with age at onset for autoimmune diabetes

Introduction

Autoimmune diabetes has different clinical manifestations related to the age at onset. It is divided into several subtypes, including “classical” type 1 diabetes (T1D) and latent autoimmune diabetes in adults (LADA). The LADA is considered a slowly progressing subtype of autoimmune diabetes, although the clinical picture is more similar to type 2 diabetes.

Material and methods

The aim of this study is to investigate whether genetic predisposition influences age at onset in autoimmune diabetes. We studied rs2476601 PTPN22 gene polymorphism and HLA DR, HLA-DQB1 in 175 patients with classical type 1 diabetes, 80 LADA, and 151 control subjects from north-east Poland.

Results

The frequencies of the PTPN22 TT genotype were higher in the group of patients with classical type 1 diabetes (6.3%) and LADA (11.3%) than in control subjects (0.7%) (p = 0.02 and p = 0007, respectively). In patients with classical type 1 diabetes we observed an increasing trend in frequencies of genotype TT dependent on age at onset (3.9% (0-5 year olds), 6.0% (6-15 year-olds), 8.2% (16-25 year olds), p = 0.048). The incidence of predisposing human leukocyte antigen (HLA) genotypes HLA DR3/DQB1*02 and DR4/DQB1*0302 was found to decrease in the group with type 1 diabetes in relation to age at onset and LADA (HLA DR3/DQB1*02 – 69.2% (0-5 year olds), 57.0% (6-15 year olds), 51.0% (16-25 year olds), 46.3% (LADA), p = 0.032; HLA DR4/DQB1*0302 – 80.8% (0-5 year olds), 63.0% (6-15 year olds), 51.0% (16-25 year olds), 43.8% (LADA), p = 0.0003), and to increase for the protective allele DQB1*0602 (0.0% (0-5 year olds), 1.0% (6-15 year olds), 2.0% (16-25 year olds), 6.3% (LADA), p = 0.029).

Conclusions

Thus, age at onset for autoimmune diabetes appears to be related to a combination of predisposing and protective HLA alleles. Against a background of HLA genetic predisposition, other non-HLA loci may influence age at onset for late autoimmune diabetes.     

HLA-DR and -DQ gene polymorphism in Latvian patients with insulin-dependent diabetes mellitus

Abstract: Latvian insulin-dependent diabetes mellitus (IDDM) patients ( n =101) and healthy controls ( n = 111) were analyzed for HLA-DR and DQ polymorphism. DR3-DQ2 and DR4-DQ8 were positively associated and DR15-DQ6, DR13-DQ6, DR1-DQ5 and DQ7 negatively associated with the disease. The incidence of LDDM in Latvia is very low (6.5 per 100,000) compared to Sweden (24.4 per 100,000), even though Latvia is close to Sweden. The reasons for the decreased incidence are not clear. When the negatively associated DQ were taken together in the healthy controls, more than 75% of the healthy controls were positive for one of the four negatively associated DQ molecules. The excess frequency of the negatively associated DQ molecules in the general population could explain the lower incidence of IDDM in Latvia. Association of HLA-DR and DQ genes with autoantibody markers shows DR3, but not DQ2, to be increased in GAD65 antibody-positive compared to antibody-negative patients. This association was not observed with ICA512 antibodies.     

Modulation of insulitis and type 1 diabetes by transgenic HLA-DR3 and DQ8 in NOD mice lacking endogenous MHC class II

To evaluate the contributions of DR3 and DQ8 to the etiopathogenesis of type 1 diabetes in a diabetes-predisposing milieu, we developed human leukocyte antigen (HLA) transgenic mice on the nonobese diabetic (NOD) background in the absence of the endogenous class II molecule, I-A(g7) and studied the incidence of both spontaneous and experimental (induced) autoimmune diabetes. Transgenic expression of HLA-DR3 and -DQ8 (either alone or in combination) did not confer susceptibility to spontaneous or cyclophosphamide-induced type 1 diabetes. Expression of I-A(g7) was mandatory for development of spontaneous or cyclophosphamide-induced diabetes. However, multiple low doses of streptozotocin could induce diabetes in all groups of mice independent of the class II molecules expressed. In unmanipulated mice, only islets from I-A(g7+/+) mice revealed significant intra-islet infiltration. Although a characteristic peri-insulitis/peri-ductulitis was present in Abeta(0)/NOD mice, islets from DR3, DQ8 and DR3 x DQ8 double transgenic mice demonstrated significantly less infiltration. In conclusion, transgenic expression of HLA-DR3 and -DQ8 associated with predisposition to type 1 diabetes alone is not sufficient to induce spontaneous diabetes in NOD mice lacking endogenous class II molecules.     

The peptide-binding motif of HLA-DR8 shares important structural features with other type 1 diabetes-associated alleles

The objective of this study was to characterize the peptide-binding motif of the major histocompatibility complex (MHC) class II HLA-DR8 molecule included in the type 1 diabetes-associated haplotype DRB1(*)0801-DQA1(*)0401/DQB1(*)0402 (DR8-DQ4), and compare it with that of other diabetes-associated MHC class II alleles; DR8-bound peptides were eluted from an HLA-DR homozygous lymphoblastoid cell line. The repertoire was characterized by peptide sequencing using a LTQ ion trap mass spectrometer coupled to a multidimensional liquid chromatography system. After validation of the spectra identification, the definition of the HLA-DR8 peptide-binding motif was achieved from the analysis of 486 natural ligands, based on serial alignments of all possible HLA-DR-binding cores. The DR8 motif showed a strong similarity with the peptide-binding motifs of other MHC class II diabetes-associated alleles, HLA-DQ8 and H-2 I-A(g7). Similar to HLA-DQ8 and H-2 I-A(g7), HLA-DR8 preferentially binds peptides with an acidic residue at position P9 of the binding core, indicating that DR8 is the susceptibility component of the DR8-DQ4 haplotype. Indeed, some DR8 peptides were identical to peptides previously identified as DQ8- or I-A(g7) ligands, and several diabetes-specific peptides associated with DQ8 or I-A(g7) could theoretically bind to HLA-DR8. These data further strengthen the association of HLA-DR8 with type I diabetes.     

Role of HLA class II genes in susceptibility and resistance to multiple sclerosis: studies using HLA transgenic mice

Multiple sclerosis (MS), an inflammatory and demyelinating autoimmune disease of CNS has both, a genetic and an environmental predisposition. Among all the genetic factors associated with MS susceptibility, HLA class II haplotypes such as DR2/DQ6, DR3/DQ2, and DR4/DQ8 show the strongest association. Although a direct role of HLA-DR alleles in MS have been confirmed, it has been difficult to understand the contribution of HLA-DQ alleles in disease pathogenesis, due to strong linkage disequilibrium. Population studies have indicated that DQ alleles may play a modulatory role in the progression of MS. To better understand the mechanism by which HLA-DR and -DQ genes contribute to susceptibility and resistance to MS, we utilized single and double transgenic mice expressing HLA class II gene(s) lacking endogenous mouse class II genes. HLA class II transgenic mice have helped us in identifying immunodominant epitopes of PLP in context of various HLA-DR and -DQ molecules. We have shown that HLA-DR3 transgenic mice were susceptible to PLP_91–110 induced experimental autoimmune encephalomyelitis (EAE), while DQ6 (DQB1*0601) and DQ8 (DQB1*0302) transgenic mice were resistant. Surprisingly DQ6/DR3 double transgenic mice were resistant while DQ8/DR3 mice showed higher disease incidence and severity than DR3 mice. The protective effect of DQ6 in DQ6/DR3 mice was mediated by IFNγ, while the disease exacerbating effect of DQ8 molecule was mediated by IL-17. Further, we have observed that myelin-specific antibodies play an important role in PLP_91–110 induced EAE in HLA-DR3DQ8 transgenic mice. Based on these observations, we hypothesize that epistatic interaction between HLA-DR and -DQ genes play an important role in predisposition to MS and our HLA transgenic mouse model provides a novel tool to study the effect of linkage disequilibrium in MS.     

The interferon-induced helicase C domain-containing protein 1 gene variant (rs1990760) as an autoimmune-based pathology susceptibility factor

PurposeAutoimmune diseases are a group of complex diseases localized in multiple organ systems, with a wide spectrum of symptoms and still unclear causes. The aim of the present study was to analyse a possible association of three autoimmune disabilities - Multiple sclerosis (MS), LADA diabetes and Graves’ disease (GD) with single nucleotide polymorphism (SNP; rs1990760) in the IF IH1 gene (also known as a melanoma differentiation-associated protein 5 - MDA5) within the Polish population. An additional goal was also to look for a correlation between this polymorphism and different clinical patient-related factors.Materials and methodsThe study population consisted of four groups of 944 unrelated Polish origin Caucasian patients – 324 with GD, 171 with MS, 49 with LADA diabetes and 400 healthy subjects as a control group. The SNP analysis was performed using the allelic discrimination technique.Results & ConclusionsThere were significant associations of risk T allel of the analyzed polymorphism with all studied autoimmune diseases (GDOR = 1.34, p = 7.02e-03; MSOR = 1.36, p = 2.17e-02; LADA – OR = 3.36, p = 8.73e-07). We also found that the frequency of CT and TT genotypes of the rs1990760 IFIH1 gene only in females (with LADA, GD, MS) was significantly higher than those in the female control group (47%, 41% vs 44%, 34%; p = 1.32e-03, p = 4.39e-04; OR = 2.08, 95%CI: (1.33–3.28), OR = 2.29, 95% CI: (1.44–3.65) respectively). Our research has shown significant differences regarding some clinical features (BMI, TRAb, TSH, HbA1C, anti-GAD antibodies) and age at the beginning of the studied autoimmune disabilities. This study showed an association of rs1990760 polymorphism in the IFIH1 gene in the development of GD, LADA diabetes and MS within the Polish population. To our knowledge, this is the first study to investigate the relationship between IFIH1 polymorphisms and the risk of the development of MS and LADA in Poland.     

HLA-DRB1-DQA1-DQB1 genotype and frequency of enterovirus in longitudinal monthly fecal samples from healthy infants

Enterovirus infections may be involved in the etiology of type 1 diabetes (T1D), which is strongly associated with certain human leukocyte antigen (HLA) class II haplotypes. Our aim was to assess whether HLA genotypes conferring varying degrees of risk for T1D were associated with enterovirus gut infections. From the general Norwegian population, 190 healthy infants at high-risk for T1D (DR4-DQ8/DR3-DQ2), and 383 infants without this genotype were identified. Non-DR4-DQ8/DR3-DQ2 genotypes were further categorized as conferring either an increased-to-moderate risk (DR4-DQ8 or DR3-DQ2), were protective (DQB1*06:02), or were neutral (all other genotypes). A total of 4626 monthly fecal samples taken between age 3 and 12?mo were tested for enterovirus RNA using real-time PCR. Enterovirus prevalence was 11.5% among high-risk children, and 12.2% in other children (adjusted odds ratio: 1.23, p=0.12). The prevalence was 11.3% in those with increased-to-moderate risk, 13.0% in the protective group, and 12.6% in the neutral group (likelihood ratio test, 3 d.f.: p=0.37). In conclusion, there was no statistically significant association between HLA genotype and the occurrence of human enterovirus gut infections.     

Insulin gene VNTR, CTLA-4 +49A/G and HLA-DQB1 alleles distinguish latent autoimmune diabetes in adults from type 1 diabetes and from type 2 diabetes group

Recent research has underlined the need to explore pathogenic, genetic and clinical spectrum of adult onset autoimmune diabetes, also known as latent autoimmune diabetes in adults (LADA). We aimed to investigate whether genetic factors that are associated with type 1 diabetes (T1D) susceptibility, namely HLA-DQB1 alleles, cytotoxic T-lymphocyte antigen 4 gene (CTLA-4) and insulin gene (INS) polymorphisms, are also associated with an atypical subset of patients diagnosed with type 2 diabetes (T2D). The case-control study included 70 T1D, 305 T2D and 252 nondiabetic controls. The T2D group was divided into atypical T2D (LADA, n = 61) or typical T2D (n = 244) subgroups based on the presence of at least one pancreas-specific antibody. Our data suggested that HLA-DQB1 alleles of all three risk classes, INS variable number of tandem repeat (VNTR) I/I and CTLA-4 +49 GG or AG genotypes, were independent risk factors for developing LADA and could be used as a diagnostic tool to discriminate between LADA and T2D. Additionally, there was an increased association between LADA and CTLA-4 diabetes-susceptibility genotypes and decreased association with INS VNTR and high-risk HLA-DQB1 alleles, compared with T1D. Our study suggested the need for further investigation into the genetic background and functional genomics of LADA in comparison with T1D and T2D.     

The HLA-DRB1*0405 haplotype is most strongly associated with IDDM in Algerians.

Insulin-dependent diabetes mellitus (IDDM) in Caucasians is strongly associated with HLA-DR3-DQ2 and DR4-DQ8. In order to investigate the HLA class II associations with IDDM in Algerians, we have used polymerase chain reaction (PCR) and sequence specific oligonucleotide analysis (SSO) to identify DQA1, DQB1, and DRB1 alleles, haplotypes and genotypes in 50 unrelated IDDM patients and 46 controls from a homogeneous population in Western Algeria. Both DRB1*0301-DQA1*0501-DQB1*0201 (DR3-DQ2) and DRB1*04-DQA1*0301-DQB1*0302 (DR4-DQ8) haplotypes were found at increased frequencies among the patients compared to controls (45% vs. 13%, RR = 5.5, Pc < 10(-5) and 37% vs. 4%, RR = 12.9, Pc < 10(-4), respectively). Among the latter, in contrast to other Caucasian populations, only DRB1*0405-DQA1*0301-DQB1*0302 was significantly increased in the Algerian patients (25% vs. 1% in controls, RR = 30.3, Pc < 10(-3). Accordingly, the highest risk of disease was observed in DRB1*0301-DQA1*0501-DQB1*0201/DRB1*0405-DQA1+ ++*0301-DQB1*0302 heterozygotes (34% in patients vs. 0% in controls; RR = 49; Pc < 10(-3). This observation and its comparison with DR-DQ haplotypes in other ethnic groups suggest that the DRB1*0405 allele which encodes an Asp57-negative beta chain may contribute to IDDM susceptibility in a similar way as Asp57-negative DQ beta chains.     

Tri-SNP polymorphism in the intron of HLA-DRA1 affects type 1 diabetes susceptibility in the Finnish population

Genes in the HLA class II region include the most important inherited risk factors for type 1 diabetes (T1D) although also polymorphisms outside the HLA region modulate the predisposition to T1D. This study set out to confirm a recent observation in which a novel expression quantitative trait locus was formed by three single nucleotide polymorphisms (SNP) in the intron of HLA-DRA1 in DR3-DQ2 haplotypes. The SNPs significantly increased the risk for T1D in DR3-DQ2 homozygous individuals and we intended to further explore this association, in the Finnish population, by comparing two DR3-DQ2 positive genotypes. Cohorts with DR3-DQ2/DR3-DQ2 (N = 570) and DR3-DQ2/DR1-DQ5 (N = 1035) genotypes were studied using TaqMan analysis that typed for rs3135394, rs9268645 and rs3129877. The tri-SNP haplotype was significantly more common in cases than controls in the DR3-DQ2/DR3-DQ2 cohort (OR = 1.70 CI 95% = 1.15–2.51P = 0.007). However, no significant associations could be observed in the DR3-DQ2/DR1-DQ5 cohort.     

Association of variants in genes involved in pancreatic β-cell development and function with type 2 diabetes in North Indians

Variants in genes involved in pancreatic β-cell development and function are known to cause monogenic forms of type 2 diabetes and are also associated with complex form. In this study, we studied the genetic association of polymorphisms in such important genes with type 2 diabetes in the high-risk Indians. We genotyped 91 polymorphisms in 19 genes (ABCC8, HNF1A, HNF1B, HNF4A, INS, INSM1, ISL1, KCNJ11, MAFA, MNX1, NEUROD1, NEUROG3, NKX2.2, NKX6.1, PAX4, PAX6, PDX1, USF1 and WFS1) in 2025 unrelated North Indians of Indo-European ethnicity comprising of 1019 diabetic and 1006 non-diabetic subjects. HNF4A promoter P2 polymorphisms rs1884613 and rs2144908, which are in high linkage disequilibrium, showed significant association with type 2 diabetes (odds ratio (OR)=1.37 (95% confidence interval (CI) 1.19-1.57), P=9.4 × 10(-6) for rs1884613 and OR=1.37 (95%CI 1.20-1.57), P=6.0 × 10(-6) for rs2144908), as previously shown in other populations. We observed body mass index-dependent association of these variants with type 2 diabetes in normal-weight/lean subjects. Variants in USF1, ABCC8, ISL1 and KCNJ11 showed nominal association, while haplotypes in these genes were significantly associated. rs3812704 upstream of NEUROG3 significantly increased risk for type 2 diabetes in normal-weight/lean subjects (OR=1.68 (95%CI 1.25-2.24), P=4.9 × 10(-4)). Thus, pancreatic β-cell development and function genes contribute to susceptibility to type 2 diabetes in North Indians.