Autoimmune adrenocortical failure in Norway autoantibodies and human leukocyte antigen class II associations related to clinical features

Autoimmune destruction of the adrenal cortex is the most common cause of primary adrenocortical insufficiency (Addison's disease) in industrialized countries. We have investigated a large Norwegian cohort of patients with Addison's disease in terms of clinical manifestations, autoantibodies, and human leukocyte antigen (HLA) class II haplotypes. The study comprised 94 patients (54 females) of ages 6-85 yr (mean 45 yr) with, either isolated Addison's disease or part of autoimmune polyendocrine syndrome type II. Among those diagnosed before the age of thirty, 53% were men, while among those diagnosed at 30 or above, 30% were men. Altogether 77 (82%) of the 94 patients had autoantibodies against 21-hydroxylase (21OH). Thirty-eight of the 40 patients with disease duration 5 yr or less had such autoantibodies. This frequency fell to 60% among patients with a disease duration greater than 35 yr. Five women had gonadal failure. This failure correlated with antibodies against side-chain cleavage enzyme (P = 0.03). Antibodies against glutamic acid decarboxylase and IA2 correlated with the presence of type 1 diabetes (P < 0.005 and P = 0.003, respectively). The frequency of the HLA DRB1*03-DQA1*05-DQB1*02 (DR3-DQ2) and DRB1*04-DQA1*03-DQB1*0302 (DR4-DQ8) haplotypes were positively correlated to Addison's disease, whereas the DRB1*01-DQA1*0101-DQB1*0501 (DR1-DQ5) haplotype was negatively correlated. In addition, the DRB1*04 subtype DRB1*0404 was increased among Addison patients relative to controls. We verify that autoimmunity is the main cause of Addison's disease in our cohort. In younger patients, the disease is equally common in men and women. Measurement of autoantibodies against 21OH is a valuable tool in establishing the etiological diagnosis, especially in patients with a short disease duration. Addison's disease is associated with the DR3-DQ2 and DR4 (0404)-DQ8 haplotypes. A particularly high risk for disease development is observed when these occur in a heterozygous combination (DR3-DQ2/DR4-DQ8).     

Specific human leukocyte antigen DQ influence on expression of antiislet autoantibodies and progression to type 1 diabetes

CONTEXT: Human leukocyte antigen (HLA) DQ haplotypes have the strongest genetic association with type 1 diabetes (T1DM) risk. OBJECTIVE: The objective of the study was to analyze whether HLA DQ alleles influence the development of antiislet autoantibodies, the progression to T1DM among autoantibody-positive relatives, or both. DESIGN: The Diabetes Prevention Trial-1 screened more than 90,000 nondiabetic relatives of patients for cytoplasmic islet-cell autoantibody (ICA) expression between 1994 and 2002. SETTING: The study was conducted in the general community. PARTICIPANTS: The Diabetes Prevention Trial-1 found 2817 ICA-positive relatives who were tested for biochemical autoantibodies (GAD65, ICA512, and insulin) and HLA-DQ haplotypes, and 2796 of them were followed up for progression to diabetes for up to 8 yr (median, 3.6 yr). MAIN OUTCOME MEASURE: Progression to T1DM was measured. RESULTS: High-risk DQ haplotypes and genotypes were associated with a higher percentage of relatives expressing multiple biochemical autoantibodies and higher T1DM risk (e.g., respectively, 59 and 36% at 5 yr for carriers of the DQA1*0301-DQB1*0302/DQA1*0501-DQB1*0201 genotype). The number of autoantibodies expressed significantly increased T1DM risk and across different DQ genotypes, autoantibody positivity directly correlated with diabetes risk. However, multivariate analyses indicated that the influence of most genotypes on T1DM risk was not independent from autoantibody expression, with the possible exception of DQA1*0102-DQB1*0602. Specific genotypic combinations conferred 5-yr diabetes risks significantly lower (e.g. 7%-DQA1*0201-DQB1*0201/DQA1*0501-DQB1*0201 and 14%-DQA1*0301-DQB1*0301/DQA1*0501-DQB1*0201) than when those haplotypes were found in other combinations. CONCLUSION: HLA DQ alleles determine autoantibody expression, which is correlated with diabetes progression. Among autoantibody-positive relatives, most HLA DQ genotypes did not further influence T1DM risk.     

Possible human leukocyte antigen-mediated genetic interaction between type 1 and type 2 Diabetes

We assessed the prevalence of families with both type 1 and type 2 diabetes in Finland; and we studied, in patients with type 2 diabetes, the association between a family history of type 1 diabetes, glutamic acid decarboxylase (GAD) antibodies (GADab), and type 1 diabetes-associated human leukocyte antigen (HLA) DQB1-genotypes. Further, in mixed type 1/type 2 diabetes families, we investigated whether sharing an HLA haplotype with a family member with type 1 diabetes influenced the manifestation of type 2 diabetes. Among 695 families ascertained through the presence of more than 1 patient with type 2 diabetes, 100 (14%) also had members with type 1 diabetes. Type 2 diabetic patients from the mixed families had, more often, GADab (18% vs. 8%, P < 0.0001) and DQB1*0302/X genotype (25% vs. 12%, P = 0.005) than patients from families with only type 2 diabetes; but they had a lower frequency of DQB1*02/0302 genotype, compared with adult-onset type 1 patients (4% vs. 27%, P < 0.0001). In the mixed families, the insulin response to oral glucose load was impaired in patients who had HLA class II risk haplotypes, either DR3(17)-DQA1*0501-DQB1*02 or DR4*0401/4-DQA1*0301-DQB1*0302, compared with patients without such haplotypes (P = 0.016). This finding was independent of the presence of GADab. We conclude that type 1 and type 2 diabetes cluster in the same families. A shared genetic background with a patient with type 1 diabetes predisposes type 2 diabetic patients both to autoantibody positivity and, irrespective of antibody positivity, to impaired insulin secretion. The findings support a possible genetic interaction between type 1 and type 2 diabetes mediated by the HLA locus.     

IDDM2/insulin VNTR modifies risk conferred by IDDM1/HLA for development of Type 1 diabetes and associated autoimmunity

AIM/HYPOTHESIS: Type 1 diabetes (T1D) is an autoimmune disease with multiple susceptibility genes. The aim of this study was to determine whether combining IDDM1/HLA and IDDM2/ insulin( INS) 5' variable number of tandem repeat locus (VNTR) genotypes improves T1D risk assessment. METHODS: Patients with T1D (n=488), control subjects (n=846), and offspring of parents with T1D (n=1122) were IDDM1 and IDDM2 genotyped. Offspring were followed for islet autoantibodies and T1D from birth until the age of 2 to 12 years. RESULTS: Compared to the I/I INS VNTR genotype, the I/III and III/III genotypes reduced T1D risk conferred by IDDM1/HLA in all HLA genotype categories of the case-control cohort by 1.6-fold to three-fold. The highest T1D risk was associated with INS VNTR class I/I plus HLA DR3/DR4-DQ8 (20.4% in patients, 0.6% in control subjects) or HLA DR4-DQ8/DR4-DQ8 (6.3% in patients, 0.2% in control subjects). In the offspring, HLA DR3/DR4-DQ8 and DR4-DQ8/DR4-DQ8 conferred increased risk for early development of islet autoantibodies (14.6% and 12.9% by age 2 years). Offspring with these high risk IDDM1 genotypes plus the INS VNTR class I/I genotype (n=71; 6.3%) had the highest risk of developing islet autoantibodies (21.8% by age 2 years vs 8.9% in offspring with high risk IDDM1 plus INS VNTR class I/III or III/III genotypes, p<0.05) and T1D (8.5% by age 6 years vs 4.3%). Offspring who developed autoantibodies to multiple antigens had increased frequencies of both high risk IDDM1 and IDDM2 genotypes (p<0.0001), whereas offspring who developed autoantibodies to GAD only had increased frequencies of high risk IDDM1 and protective IDDM2 genotypes, suggesting that IDDM2 influences the autoimmune target specificity. CONCLUSION/INTERPRETATION: Combining IDDM1 and IDDM2 genotyping identifies a minority of children with an increased T1D risk.     

HLA-DQB1*0201/0302 is associated with severe retinopathy in patients with IDDM

Summary Some insulin-dependent diabetic (IDDM) patients develop severe forms of retinopathy. Putative risk factors such as hypertension, poor metabolic control, nephropathy and growth hormone levels do not fully explain the progress of retinopathy in these patients. It has been discussed whether there is a genetic marker, since some diabetic patients without any known predisposing risk factors develop severe retinopathy and others do not. In the present study, HLA-DR and DQ were compared in two patient groups with IDDM. One group consisted of patients with early-onset diabetes, with severe non-proliferative or proliferative retinopathy; the other group had no or only mild signs of retinopathy. High resolution HLA typing was carried out by polymerase chain reaction (PCR) and hybridization with allele specific probes. Alleles on the DR3-DQ2 haplotype, DRB1^*0301, DQA1*0501 and DQB1^*0201, were more frequent in patients with severe retinopathy. A difference was seen when combining certain alleles in the genotypes of DQA1*03/0501 (p > 0.05) and DQB1^*0201/0302 (p < 0.01). The findings of the present study suggest that DQB1^*0201/0302 is the strongest genetic marker for severe retinopathy and DRB1*0301/0401 only has a secondary influence when combined with this genotype. It seems as if IDDM patients who are positive for the genotype DR3-DQ2/DR4-DQ8 (DRB1^*0301-DQA1*0501-DQB1^*0201/DRB1*0401 -DQA1^*03-DQB1*0302) are at greater risk of developing severe retinopathy. [Diabetologia (1996) 39: 1313–1317] Received: 15 February 1996 and in revised form: 24 April 1996     

Inheritance of MHC class II genes in IDDM studied in population-based affected and control families

Summary The transmission of HLA-DR and DQ was compared between 46 families with at least one child affected by insulin dependent diabetes mellitis (IDDM) and 43 healthy control families. In the patient families, there was an increased transmission of DR4 (p<0.025) and DQB1*0302 (p<0.01) from both parents to the index patient. There was an increased transmission of DQB1*0302 (p<0.03) from the mothers only. The non-inherited maternal haplotypes showed a significantly decreased frequency (p<0.01) of positively associated haplotypes (DR4-DQA1* 0301-DQB1*0302, DR3-DQA1*0501-DQB1*0201) compared to all parental haplotypes in the control families. In the control families neither transmission rates nor frequencies of non-inherited haplotypes differed from those expected in the control families. In conclusion, the observed reduction of IDDM-positively associated haplotypes in patient non-inherited maternal haplotypes, but not in non-inherited paternal haplotypes, suggests that tolerance during fetal life to maternal non-inherited HLA molecules may be important to diabetes development.Abbreviations HLA Human Leucocyte antigen - NIMH non-inherited maternal haplotype - NIPH non-inherited paternal haplotype - MHC major histocompatibility complex - RPE relative predispositional effect - RFLP restriction fragment length polymorphism - w/v weight volume     

Genetic and humoral autoimmunity markers of type 1 diabetes: from theory to practice

Type 1 A diabetes mellitus (T1AD) results from the autoimmune destruction of the insulin producing pancreatic beta-cells. The largest contribution to genetic susceptibility comes from several genes located in the major histocompatibility complex on chromosome 6p21.3 (IDDM1 locus), accounting for at least 40% of the family aggregation of this disease. The highest-risk human leukocyte antigen HLA genotype for T1AD is DR3-DQA1*0501-DQB1*0201/DR4-DQA1*0301-DQB1*0302, whereas -DR15-DQA1*0102-DQB1*0602 haplotype is associated with dominant protection. Three other T1D loci associated with predisposition are the Variable Number for Tandem Repeats (VNTR) near the insulin gene (IDDM2), which accounts to 10% of genetic susceptibility, the Cytotoxic T-Lymphocyte-associated Antigen (CTLA-4)(IDDM 12) and the Protein Tyrosine Phosphatasis Nonreceptor-type 22 (PTPN22). Many other gene suspected to predispose to autoimmunity have been investigated. T1AD is frequently associated with autoimmune thyroid disease, celiac disase, Addison s disease and many other autoimmune diseases, characterized by organ-specific autoantibodies and related to the same genetic background. Using these autoantibodies, organ specific autoimmunity may be detected before the development of clinical disease preventing significant morbidity.     

Genetic determinants of 21-hydroxylase autoantibodies amongst patients of the type 1 diabetes genetics consortium

Background: Autoantibodies to 21-hydroxylase (21OH-AA) precede the onset of autoimmune Addison's disease (AD) and are found in 1.5% of individuals with type 1 diabetes mellitus (T1DM). The greatest genetic risk for both disorders is found in the major histocompatibility complex (MHC), suggesting a common pathophysiology between AD and T1DM. Screening for 21OH-AA in newly diagnosed T1DM patients is a valuable prognostic tool, made stronger when MHC genotype is considered. Methods: The Type 1 Diabetes Genetics Consortium has collected genotype data in T1DM subjects with tissue-specific autoantibody typing. Genotype and phenotype data in individuals positive and negative for 21OH-AA are compared. Results: Major genetic risk for 21OH-AA is in the MHC haplotypes DRB1*04-DQB1*0302 (primarily DRB1*0404) and DRB1*0301-DQB1*0201. Protective effects in class II MHC haplotypes DRB1*0101-DQB1*0501 and DRB1*0701-DQB1*0202 also were detected. There is no difference in the presence of HLA-B15 and little difference in the presence of HLA-B8 (after class II effects are accounted for) in T1DM patients with 21OH-AA compared with known associations (HLA-B8 positive and HLA-B15 negative) in AD. Conclusions: In 21OH-AA(+) subjects, genetic risk is found mainly in MHC class II haplotypes DR3 and DR4 but not class I alleles (HLA-B8 or HLA-B15). This suggests a difference between autoantibody formation (class II dependent) and progression to overt disease (class I dependent) in AD.     

Temporal changes in the frequencies of HLA genotypes in patients with Type 1 diabetes--indication of an increased environmental pressure?

AIMS/HYPOTHESIS: The incidence of Type 1 diabetes has increased 2.5 times during the time period from 1966 to 2000 in Finland-a general trend seen in almost all developed countries that can only be explained by environmental factors. The aim of this study was to test the possible effect of a changing environment on distribution of genotypes associated with disease susceptibility. METHODS: HLA DRB1-DQA1-DQB1 genes and two diabetes-associated polymorphisms at IDDM2 and IDDM12 were analyzed. The frequencies of genotypes were compared between cases diagnosed with childhood-onset Type 1 diabetes during the period of 1939-1965 (n=367) and those diagnosed between 1990 and 2001 (n=736). Chi-square statistics or the Fisher's Exact test were used for the comparison of frequencies of analyzed haplotypes and genotypes in the two groups. RESULTS: The frequencies of (DR3) -DQA1*05-DQB1*02 and (DR4) -DQB1*0302 risk haplotypes and the high risk (DR3) -DQA1*05-DQB1*02/DRB1*0401-DQB1*0302 genotype were higher while proportion of patients carrying protective haplotypes-(DR15) -DQB1*0602 and (DR1301) -DQB1*0603-or protective genotypes was lower in patients diagnosed before 1965 as compared to those who developed disease after 1990. No temporal variation was found in the frequencies of genotypes at IDDM2 and IDDM12. CONCLUSION/INTERPRETATION: Our data suggest that the need for genetic susceptibility to develop Type 1 diabetes has decreased over time due to an increasing environmental pressure and this results in a higher disease progression rate especially in subjects with protective HLA genotypes.     

HLA-DR-DQ haplotypes and genotypes in Finnish patients with rheumatoid arthritis

OBJECTIVES: To elucidate the contribution of HLA-DR-DQ haplotypes and their genotypic combinations to susceptibility to rheumatoid arthritis, and to evaluate the various models for HLA associated risk for the disease in a series of Finnish patients. METHODS: 322 Finnish patients with rheumatoid arthritis were typed for common north European HLA-DR-DQ haplotypes and compared with a series of 1244 artificial family based control haplotypes. RESULTS: The association of the so called shared epitope (SE) haplotypes (DRB1*0401, *0404, *0408, and *01) with rheumatoid arthritis was confirmed. The DRB1*0401 haplotypes carried a far stronger risk for the disease than the (DRB1*01/10)-(DQA1*01)-DQB1*0501 haplotypes. Seven protective HLA haplotypes--(DRB1*15)-(DQA1*01)-DQB1*0602; (DRB1*08)-(DQA1*04)-DQB1*04; (DRB1*11/12)-DQA1*05-DQB1*0301; (DRB1*1301)-(DQA1*01)-DQB1*0603; (DRB1*1302)-(DQA1*01)-DQB1*0604; (DRB1*07)-DQA1*0201-DQB1*0303; and (DRB1*16)- (DQA1*01)-DQB1*0502--were identified. In accordance with the reshaped shared epitope hypothesis, all the protective DRB1 alleles in these haplotypes share either isoleucine at position 67 or aspartic acid at position 70 in their third hypervariable region motif. However, differences in the disease risk of haplotypes carrying the same DR but different DQ alleles were also found: (DRB1*07)-DQA1*0201-DQB1*0303 was protective, while (DRB1*07)-DQA1*0201-DQB1*02 was neutral. The same haplotypes carried different risks for rheumatoid arthritis depending on their combination in genotypes. CONCLUSIONS: When assessing the influence of HLA genes on the susceptibility to rheumatoid arthritis, not only should the HLA-DR or -DQ alleles or haplotypes be unravelled but also the genotype. The effect of HLA class II region genes is more complicated than any of the existing hypotheses can explain.     

Absolute risk of childhood-onset type 1 diabetes defined by human leukocyte antigen class II genotype: a population-based study in the United Kingdom

The autoimmune disease process leading to childhood-onset type 1 diabetes appears to start in infancy, and decisions on treatment to prevent initiation of autoimmunity will need to be based on genetic susceptibility alone. We set out to quantify the absolute risk associated with human leukocyte antigen (HLA) DRB1-DQA1-DQB1 class II genotypes and to develop strategies for recruitment into primary prevention trials. HLA class II haplotype- and genotype-specific risks were derived from 753 United Kingdom families from the Bart's-Oxford population-based study of type 1 diabetes and combined with incidence data from the region to calculate the absolute risk of development of diabetes. A hierarchy of susceptibility was established for both HLA class II haplotypes and genotypes, and the sensitivity and specificity of each genotype was established relative to age at disease onset. Highest risk was conferred by the genotype DRB1*03-DQA1*0501-DQB1*0201/DRB1*0401-DQA1*0301-DQB1*0302 (5% absolute risk of diabetes by age 15 yr), although sensitivity was only 22.6%. Combining the six highest risk genotypes conferred similar risk but increased sensitivity to 36.6% and was most sensitive for diagnosis of diabetes before age 5 yr (48.4%), whereas inclusion of 11 genotypes achieved the same sensitivity for diagnosis for ages 10-14 yr. Analysis of genotype-specific risk should form the basis for design of future primary prevention trials in the general population.     

Association of hla–dr4-dw15 (drb1*0405) and dr10 with rheumatoid arthritis in a spanish population

Objective. To analyze the associations of HLA class II antigens with rheumatoid arthritis (RA) in a Spanish population. Methods. We used DNA oligotyping to determine DR types, DQA1 and DQB1 alleles, and DR4 variants in 70 unrelated seropositive RA patients and 189 healthy controls living in Spain. Results. A significantly higher frequency of DR4 was seen in RA patients compared with controls (relative risk [RR] = 2.40). The DR10 specificity correlated most strongly with disease susceptibility (RR = 3.84). A significant decrease in the frequency of DR7 was observed in the RA patients (RR = 0.48). DR4-Dw15 (DRB1*0405) was found to be the unique DR4 allele associated with RA (RR = 4.27, P < 0.05), whereas Dw4 (DRB1*0401) and Dw14 (DRB1*0404/0408) showed no association, and both D10 (DRB1*0402) and Dw13 (DRB1*0403/0407) were negative risk factors for the disease. Approximately one-third of the cases of RA could not be explained by the “shared epitope” hypothesis. Investigation of the DQ alleles associated with DR4 showed that the haplotype Dw15-DQ8 (DRB1*0405-DQB1*0302) was a susceptibility factor for RA (RR = 6.36, P < 0.05). Conclusion. Our results suggest that HLA class II alleles involved in RA susceptibility can vary among different Caucasian populations.     

Epidemiology and genetic risk of type 1 diabetes among children in Aragon community, Spain

The incidence of type 1 diabetes in children from Aragon (a population of the North of Spain) is reported determining the relations between the onset of type 1 diabetes and gender, age at diagnosis, genetic risk (HLA class II genes) or climatology factors. The population at risk was all 0-14 year-old inhabitants. Patients were identified from five sources: hospitals, primary assistance, endocrinologists, diabetic associations and diabetes camps. The degree of ascertainment was 98.93%. HLA genetic study was performed. Annual incidence was 16.4 per 100,000 per year (95% CI: 14.7-18.2). This incidence was significantly higher in males than in females, 18.7 versus 14.2 (p<0.02), and increased with age. The haplotypes (DR3)-DQB1*0201/(DR4)-DQB1*0302 and (DR3)-DQB1*0201/(DR7)-DQB1*0202 conferred the highest risk of type 1 diabetes. A relative high incidence of type 1 diabetes mellitus has been demonstrated in the Northeast of Spain, and it does not support south-to-north incidence gradient in Europe. Haplotypes that conferred a higher risk of disease agree with those founded in other Caucasic populations.     

Non-transmitted maternal HLA DQ2 or DQ8 alleles and risk of Type I diabetes in offspring: the importance of foetal or post partum exposure to diabetogenic molecules

AIMS/HYPOTHESIS: Type I (insulin-dependent) diabetes mellitus results from an immune-mediated destruction of pancreatic beta cells for which HLA haplotypes DR3-DQ2 and DR4-DQ8 represent the strongest genetic risk markers. Mothers of patients with rheumatoid arthritis carry more frequently the HLA DR4-DQ8 haplotype as non-transmitted haplotype than mothers of healthy control subjects. As maternal cells have been shown to persist in their offspring up to 30 years after birth, we investigated whether the association of HLA DR3-DQ2 and DR4-DQ8 with Type I diabetes is purely a genetic effect acting through inheritance or whether it can also act as an environmental factor, for example through foetal exposure in utero to maternal circulating cells. METHODS: We analysed the non-transmitted parental HLA DQ alleles of 464 families (1367 subjects) with a Type I diabetic offspring. HLA DQ alleles were assessed using sequence-specific primers and allele-specific oligonucleotides hybridisation. A chi-square test was done to compare allele and transmission frequencies in the respective subsets of families. RESULTS: The non-transmitted HLA DR3-DQ2 and DR4-DQ8 were more frequent in mothers than in fathers of all non- DQ2/DQ8 heterozygous diabetic offspring ( p=0.0001) as well as in offspring not carrying any HLA high-risk allele ( p=0.0243). In patients with either risk allele alone, more maternal than paternal non-transmitted risk alleles complemented the constellation to DQ2/DQ8 ( p<0.0099). CONCLUSION/INTERPRETATION: HLA high risk alleles were more frequent among maternal non-inherited (but possibly exposed) alleles than among paternal non-inherited alleles. These results indicate that HLA DR-DQ is an environmental risk factor for Type I diabetes.     

HLA-DQ haplotypes in Spanish and German families with Graves' disease: contribution to DQA1*0501-DQB1*0301 mediated genetic susceptibility from fathers.

Genetic and environmental factors are involved in the pathogenesis of Graves' disease. The human leukocyte antigen (HLA) locus is considered to be one risk factor for Graves' disease but parent of origin effects have not been studied. Therefore, we investigated the transmission of HLA risk haplotypes DQA1*0501, DQA1*0501-DQB1*0201 (DQ2), and DQA1*0501-DQB1*0301 (DQ7) in two Graves' disease family-cohorts from Spain and Germany. Altogether 208 trio-families (109 from Spain and 99 from Germany; n = 624 individuals) with Graves' disease were genotyped for HLA-DQ alleles DQA1*0501 and the haplotypes DQA1*0501-DQB1*0201 (DQ2) and DQA1*0501-DQB1*0301 (DQ7). Since both family groups-German and Spanish-showed the same pattern of HLA transmission and nontransmission, they were analyzed together. HLA DQA1*0501 and DQA1*0501-DQB1*0201 (DQ2) were significantly overtransmitted from the parents to the affected offspring (204 vs. 131, p = 0.0057, pc = 0.0228 and 109 vs. 55, p = 0.0036, pc = 0.0144, respectively). These haplotypes were preferentially transmitted from fathers and DQA1*0501-DQB1*0301 (DQ7) was also more prevalent in fathers (24.0% vs. 17.1%, p = 0.0162, pc = 0.0648). We conclude, that HLA DQA1*0501 and DQA1*0501-DQB1*0201 (DQ2) are strongly associated with Graves' disease in both populations. A parent of origin effect of risk haplotypes can not be excluded at present, warranting further family studies.     

Juvenile idiopathic arthritis (JIA) is primarily associated with HLA-DR8 but not DQ4 on the DR8-DQ4 haplotype

BACKGROUND: Juvenile idiopathic arthritis (JIA) is strongly associated with the DR8-DQ4 haplotype. The genes encoding DR8 and DQ4 are in strong linkage disequilibrium (LD) and occur together on the same HLA haplotype in almost all patients and controls. Because of the strong LD it is not clear whether DR8, DQ4, or both, are primarily associated with JIA. OBJECTIVE: To unveil the primary association of JIA--that is, with DR8 or DQ4. METHODS: DRB1, DQA1, and DQB1 alleles of 585 Norwegian and 47 Polish unrelated patients with JIA (categorised as pauciarticular and rheumatoid factor negative polyarticular JIA), and of 3155 Norwegian and 158 Polish unrelated controls, were typed using a polymerase chain reaction or oligonucleotide hybridisation and sequence-specific primers method. RESULTS: Several haplotypes which encoded DR8 (that is, carried DRB1*08) and which did not encode DQ4 (that is, did not carry DQA1*0401) were found. Such haplotypes were found in three Norwegian patients and two controls (p=0.029). In the Polish population such haplotypes were found among four patients with JIA and two controls (p=0.025). No haplotypes which carried DQA1*0401 and DQB1*0402 in the absence of DRB1*08 were found, either among patients with JIA (Polish and Norwegian) or among the controls (Polish). CONCLUSION: On the DR8-DQ4 haplotype the DRB1*08 allele is primarily associated with JIA.     

Contribution of MHC class I chain-related A (MICA) gene polymorphism to genetic susceptibility for systemic lupus erythematosus

OBJECTIVE: To evaluate the contribution of the MHC class I chain-related A (MICA) gene polymorphism to the genetic risk of systemic lupus erythematosus (SLE). METHODS: HLA-DRB1-DQA1-DQB1 genotyping, MICA exon 5 microsatellite genotyping and HLA-B8 genotyping were performed in 48 Italian SLE patients and in 158 healthy control subjects. RESULTS: Of HLA class II haplotypes, only DRB1*03-DQA1*0501-DQB1*0201 (DR3-DQ2) was significantly more frequent among SLE patients than among healthy control subjects [odds ratio (OR) = 6.5, corrected P < 0.0026]. HLA-B8 was detected in 31% SLE patients and 13% healthy control subjects (OR = 3.0, P = 0.005). The allele-wise comparison between patients and controls showed that both MICA5 (OR = 2.5, corrected P < 0.0005) and MICA5.1 (OR = 2.4, corrected P < 0.0005) were positively and MICA9 (OR = 0.2, corrected P < 0.0005) was negatively associated with the disease. The MICA5/5.1 genotype was positively associated with SLE (OR = 28.9, corrected P < 0.0015) also in subjects negative for DR3-DQ2 (OR > 22.6, corrected P < 0.011). The simultaneous presence of DR3-DQ2 and MICA5.1 was detected in 15/48 (31%) SLE and in 10/158 (6%) healthy control subjects (OR = 6.7, corrected P < 0.011). The simultaneous combination of DR3-DQ2 and MICA5 was found in 10/48 (21%) SLE patients and in only 1/158 healthy control subjects (OR = 41.3, corrected P < 0.011). Logistic regression analysis showed the independent positive associations of MICA5 and MICA5.1 and negative association of MICA9 with the disease, and revealed that the interaction of the three major markers (DR3-DQ2, MICA5 and MICA5.1) was associated with increasing genetic risk, which was highest (OR > 30.3) in DR3-DQ2-positive subjects carrying the MICA5-5.1 genotype. CONCLUSIONS: Our study provides the first demonstration of the independent association of the MICA gene polymorphism with genetic risk of SLE.     

Contribution of selective HLA-DRB1/DQB1 alleles and haplotypes to the genetic susceptibility of type 1 diabetes among Lebanese and Bahraini Arabs

CONTEXT: Human leukocyte antigen (HLA) class II genes contribute to the genetic susceptibility of type 1 diabetes (T1D), and both susceptible and protective alleles were implicated with its pathogenesis, which varies among various ethnic/racial groups. OBJECTIVE: This study investigated the heterogeneity in HLA class II haplotypes distribution among Bahraini and Lebanese T1D patients. DESIGN: This was a cross-sectional retrospective study. SETTING: The study was conducted at primary care private and public health centers. PATIENTS AND OTHER PARTICIPANTS: Subjects comprised 126 T1D patients and 126 healthy controls from Bahrain and 78 Lebanese T1D patients and 111 control subjects. Intervention(s): There were no interventions. RESULTS: Although Lebanese and Bahraini patients share DRB1*030101, DQB1*0201 as susceptible and DRB1*100101 and DQB1*030101 as protective alleles, DRB1*040101 was an additional susceptible allele in Bahraini patients, and DRB1*130701 and DQB1*050101 were additional susceptible and protective alleles in Lebanese, respectively. DRB1*030101-DQB1*0201 was susceptible, whereas DRB1*070101-DQB1*0201 and DRB1*110101-DQB1*030101 were protective haplotypes in Bahraini and Lebanese. DRB1*040101-DQB1*0302 and DRB1*040101-DQB1*050101 displayed different associations: they were protective in Lebanese but susceptible or neutral among Bahrainis. Whereas the frequency of homozygous DRB1*03011-DQB1*0201 was higher in Bahraini and to a lesser extent Lebanese patients, homozygous DRB1*110101-DQB1*030101 was significantly more frequent in Lebanese but not Bahraini controls, whereas DRB1*030101-DQB1*0201/DRB1*040101-DQB1*0201 was the major genotype among Bahraini patients but not Lebanese subjects in whom it was present at very low frequencies. CONCLUSION: In view of these differences between Bahraini and Lebanese, this demonstrates that the contribution of HLA class II to the genetic susceptibility to T1D must be evaluated with regard to specific HLA haplotypes and also ethnic origin and racial background.     

HLA DQA1-DQB1-TAP2 haplotypes in IDDM families: no evidence for an additional contribution to disease risk by the TAP2 locus

Summary The TAP2 gene, located in the HLA class II region, encodes a subunit of a transporter involved in the endogenous antigen-processing pathway, and has been suggested to contribute to the genetic risk for insulin-dependent diabetes (IDDM). In order to determine whether the TAP2 locus modulates the risk conferred by HLA DQ loci, HLA DQA1-DQB1-TAP2 haplotypes were analysed in 48 IDDM probands, their first degree relatives, and in 62 normal control subjects. A decreased frequency of the TAP2B allele was confirmed in this IDDM cohort (12 vs 28% in control subjects, p _c <0.05). Analysis of 73 informative meiotic events in IDDM and control families demonstrated a recombination fraction between HLA DQB1 and TAP2 loci of 0.041 (Log of the odds score=16.5; p<10^–8) indicating strong linkage between these loci. Family haplotype analysis demonstrated linkage disequilibrium between TAP2 and HLA DQA1-DQB1, and showed that the reduced frequency of TAP2B was associated with its absence on the IDDM susceptible DQA1*0301-DQB1*0302 haplotype, its low frequency on DQA1*0501-DQB1*0201, and the association of TAP2B with DQA1*0101-DQB1*0501 haplotypes which were less frequent in IDDM patients. Comparison of transmitted with non-transmitted haplotypes in IDDM families showed a slight but not significant decrease in TAP2B allele frequency on transmitted (3 of 37) vs non-transmitted (2 of 9) HLA DQA1*0501-DQB1*0201 haplotypes. No other differences were observed. Twenty-four unrelated DQA1*0501-DQB1*0201 haplotypes from non-diabetic families had a TAP2B allele frequency (4%) similar to that in IDDM haplotypes. These findings suggest that the decreased TAP2B allele frequency in Italian IDDM patients is due to HLA DQ haplotype differences between IDDM patients and control subjects, and do not support a contribution to IDDM risk by the TAP2 locus.Abbreviations ARMS Amplificatory refractory mutation system - IDDM insulin-dependent diabetes mellitus - MHC major histocompatibility complex - PCR polymerase chain reaction - TAP transporter associated with antigen processing     

Association of particular HLA class II alleles,haplotypes and genotypes with susceptibility to IDDM in the Belgian population

Summary Using a highly discriminatory DNA typing technique, based on the polymerase chain reaction and reverse dot blot hybridization, more refined results were obtained on the association of particular HLA class II alleles, haplotypes and genotypes with insulin-dependent diabetes mellitus in the Belgian population. The previously reported predisposing effect for the DRB1*0301 encoded DR3 serologic specificity was confirmed and could be assigned to the DRB3*0200 encoded DR52b serologic specificity. A second high risk haplotype, DRB1*0401-DQB1*0302 encoding the DR4-DQ8 serologic specificity, accounted for increased susceptibility both in the total insulin-dependent diabetic population and among DR4-positive patients. Moreover, we found that these DR4 associated DRB1 and DQB1 alleles act as independent risk factors. A possible role for the DPB1 locus can be rejected since the observed predisposing effect for DPB1*0202 probably occurred due to linkage disequilibrium of this allele with DRB1*0301. Particular extended haplotypes accounted for the decreased relative risk observed for the DR2, DR11 and DR13 serologic specificities. The highest relative risk was observed for those DQA1/DQB1 genotypes, allowing for the formation of 4SS (DQ^Arg52+/DQ ^Asp57–) heterodimers.Abbreviations aa Amino acid - Asp aspartic acid - Arg arginine - SSO sequence-specific oligonucleotide - PCR polymerase chain reaction - NBT nitroblue tetrazolium chloride - BCIP 5-Bromo-4-chloro-3-indolyl phosphate - RR relative risk - df degrees of freedom - HO null hypothesis - IDDM insulin-dependent diabetes mellitus