Distribution of HLA class II (DRB1/DQB1) alleles and haplotypes among Bahraini and Lebanese Arabs

The genetic relationship between Bahraini and Lebanese Arabs in terms of HLA class II (DRB1 and DQB1) gene and haplotype frequencies was investigated in a group of 90 Lebanese and 52 Bahraini Arabs. Subjects of both sexes were unrelated and HLA-DRB1 and DQB1 genes were genotyped using the polymerase chain reaction-sequence specific primer (PCR-SSP) technique. Analysis of the HLA-DRB1 alleles showed that the DRB1*040101 and DRB1*110101 alleles were more common among Lebanese, whereas DRB1*030101, DRB1*130701/1327, and DRB1*160101 alleles were more common among Bahrainis. Similarly, of the 7 HLA-DQB1 alleles analyzed, the presence of DQB1*0201 was higher among Bahrainis, whereas DQB1*030101 was higher among Lebanese. The DRB1*160101-DQB1*050101 (23.08%) and DRB1*030101-DQB1*0201 (21.15%) haplotypes were more frequent among Bahrainis, while the DRB1*110101-DQB1*030101 (56.67%), DRB1*040101-DQB1*0302 (28.89%) and DRB1*040101/DQB1*030101 (25.56%) haplotypes were more frequent in Lebanese subjects. Our results underline significant differences between these two populations in HLA class II distribution, and provide basic information for further studies of MHC heterogeneity among Arab-speaking countries, and as a reference for further anthropologic studies.     

Differences in the contribution of HLA-DR and -DQ haplotypes to susceptibility to adult- and childhood-onset type 1 diabetes in Japanese patients

To clarify heterogeneity in Japanese adult-onset type 1 diabetes, we analyzed the HLA-DR and -DQ haplotypes, depending on the clinical phenotype, and compared them with those in childhood-onset type 1 diabetes (CO). The patients in a previously reported Ehime Study were divided into subgroups by the mode of onset of diabetes: 68 acute-onset type 1 diabetic patients (AO) and 28 slowly progressive type 1 diabetic patients (SO). HLA haplotypes were compared with those of 80 CO patients and 190 control subjects. Two major susceptible HLA haplotypes in the Japanese, DRB1*0405-DQB1*0401 (DR4) and DRB1*0901-DQB1*0303 (DR9), were significantly increased in the AO and CO groups, but only DR9 was increased in the SO group. AO subjects had a higher frequency of DR9 than CO subjects. Accordingly, the DR9:DR4 frequency increased with increasing age of onset. Another susceptible haplotype, DRB1*0802-DQB1*0302 (DR8), was involved only in the CO group. Analysis of haplotype combinations revealed that DR4 and DR9 had significant dosage effects on the AO and CO groups (P < 0.0001), but only DR9 had such an effect in the SO group (P < 0.03). These results suggest differences in the contribution of HLA class II haplotypes to susceptibility of type 1 diabetes depending on the clinical phenotype and also indicate that HLA class II haplotypes may be associated with the onset age of type 1 diabetes.     

Transmission of maternal islet antibodies and risk of autoimmune diabetes in offspring of mothers with type 1 diabetes

It is suggested that the maternal transmission of islet autoantibodies increases the risk of autoimmune diabetes in mice. The aim of this study was to determine whether fetal exposure to islet autoantibodies modified the risk of type 1 diabetes in humans. Islet autoantibodies were measured at birth in 720 offspring of mothers with type 1 diabetes. Offspring were prospectively followed for the development of multiple islet autoantibodies and diabetes. Offspring who were GAD or IA-2 autoantibody positive at birth (n = 678) had significantly lower risks for developing multiple islet autoantibodies (5-year risk 1.3%) and diabetes (8-year risk 1.1%) than offspring who were islet autoantibody negative at birth (5.3%, P = 0.008; and 3%, P = 0.04, respectively). Risk remained reduced after adjustment for birth weight, gestational age, or maternal diabetes duration (adjusted hazards ratio 0.25, P = 0.007 for multiple islet autoantibodies; 0.25, P = 0.04 for diabetes). Protection in offspring with islet autoantibodies at birth was most striking in offspring without the HLA DRB1*03/DRB1*04-DQB1*0302 genotype. Maternal transmission of antibodies to exogenous insulin did not affect diabetes risk in offspring. These findings suggest that fetal exposure to islet autoantibodies in children born to mothers with type 1 diabetes may be protective against future islet autoimmunity and diabetes.     

Association between HLA class II locus and the susceptibility to Artemisia pollen-induced allergic rhinitis in Chinese population.

OBJECTIVE: The aim of the study was to determine whether susceptibility or resistance to Artemisia pollen-induced allergic rhinitis was associated with HLA class II DQA1, DQB1 loci.Study design and setting Forty-one subjects with allergic rhinitis and 41 healthy controls from Beijing were genotyped at HLA class II DQA1, DQB1 alleles by polymerase chain reaction amplification with sequence-specific primers-based technique. RESULTS: The allele frequencies of HLA-DQA1*0201, DQB1*0602 were lower in patients with allergic rhinitis compared with the controls (24.39% versus 46.34%, P = 0.038; 4.88% versus 26.83%, P = 0.007), and the frequency of DQA1*0302 was higher among patients than the controls (58.54% versus 14.63%, P = 0.00004, Pc = 0.0004). CONCLUSION AND SIGNIFICANCE: HLA-DQA1 and -DQB1 genes may be involved in the development of Artemisia pollen-induced allergic rhinitis. HLA-DQA1*0201, DQB1*0602 alleles may be a protective factor and DQA1*0302 may be a susceptible factor for Artemisia pollen-induced allergic rhinitis.     

HLA Class II Genotyping of African American Type 1 Diabetic Patients Reveals Associations Unique to African Haplotypes

HLA genotyping was performed in African American type 1 diabetic patients (n = 772) and controls (n = 1,641) in the largest study of African Americans and type 1 diabetes reported to date. Cases were from Children’s Hospital and Research Center Oakland and from existing collections (Type 1 Diabetes Genetics Consortium [T1DGC], Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications [DCCT/EDIC], and Genetics of Kidneys in Diabetes [GoKinD]). Controls were from the T1DGC and from newborn bloodspot cards. The diversity of HLA DRB1-DQA1-DQB1 haplotypes and genotypes is far greater than that found in Europeans and European Americans. Association analyses replicated many type 1 diabetes risk effects of European-derived haplotypes but also revealed novel effects for African-derived haplotypes. Notably, the African-specific “DR3” haplotype DRB1*03:02-DQA1*04:01-DQB1*04:02 is protective for type 1 diabetes, in contrast to the common and highly-susceptible DR3 DRB1*03:01-DQA1*05:01-DQB1*02:01. Both DRB1*07:01 and DRB1*13:03 haplotypes are predisposing when they include DQA1*03:01-DQB1*02:01g but are protective with DQA1*02:01-DQB1*02:01g. The heterozygous DR4/DR9 genotype, containing the African-derived “DR9” haplotype DRB1*09:01-DQA1*03:01-DQB1*02:01g, exhibits extremely high risk (odds ratio = 30.88), approaching that for DR3/DR4 in European populations. Disease risk assessment for African Americans differs greatly from risk assessment in European populations. This has profound implications on risk screening programs and underscores the need for high-resolution genotyping of multiple populations for the rational design of screening programs with tests that will fairly represent the population being screened.Type 1 diabetes is an autoimmune disease characterized by destruction of insulin-producing β-cells. The incidence and prevalence of type 1 diabetes are much higher for populations of European descent than for other ethnic groups (1). In the United States, diabetes mellitus is more common among nonwhite populations, including African Americans, than among non-Hispanic white (European ancestry) populations (2). Because type 2 diabetes is far more prevalent than type 1 diabetes in African American adults, and because the incidence of type 2 diabetes is increasing in African American youth because of the obesity epidemic, the burden of type 1 diabetes in African American youth has been less emphasized in the literature than that of type 2 diabetes (3). However, type 1 diabetes presents a serious burden among African American youth younger than 10 years of age, and African American adolescents are impacted substantially by both type 1 and type 2 diabetes (3). In fact, although type 2 diabetes incidence is increasing, type 1 diabetes is still approximately three-fold more common than type 2 diabetes in the African American pediatric population at Children’s Hospital and Research Center Oakland. Moreover, early disease onset lengthens disease duration and likely leads to complications at relatively young ages. African American individuals with diabetes are at higher risk for the chronic complications of diabetes than are non-Hispanic white (European) Americans, particularly for diabetic nephropathy (4).The incidence of type 1 diabetes varies widely around the world, partly because of ethnic differences in HLA allele and haplotype frequencies across populations. Susceptibility to type 1 diabetes is strongly associated with alleles at the DRB1 locus and at the DQA1 and DQB1 loci, which encode the α-chain and β-chain of the DQ heterodimer. In general, heterodimers that are DQα Arg52–positive and DQβ Asp57–negative represent high genetic risk for type 1 diabetes (5). Because the heterodimeric DQ molecule is encoded by two polymorphic genes, DQA1 and DQB1, individuals heterozygous for DQA1-DQB1 haplotypes have the potential to express up to four different DQ molecules on the cell surface. Heterodimers encoded in trans are postulated to help explain the extremely high risk of the heterozygous “DR3/DR4” genotype, which confers the highest genetic risk known for type 1 diabetes. Data from many reports show that specific combinations of alleles in DRB1-DQA1-DQB1 haplotypes are associated with type 1 diabetes risk.To date, few studies have been reported on HLA association with type 1 diabetes in African Americans, and some early reports may be confounded by the inclusion of type 2 diabetes patients. This study is the largest of its kind reported to date (772 cases, 1,641 controls) and was made possible by combining data from newly collected samples with data from existing collections.     

Heterozygosity or homozygosity for 2 HLA class II haplotypes predict favorable outcomes for renal cell carcinoma treated with cytokine therapy

PURPOSE: Durable responses to cytokine therapy occur in a small subset of patients with renal cell carcinoma. We determined if a common HLA genotype existed among these patients which might be associated with response and survival. MATERIALS AND METHODS: The study population consisted of 80 patients with metastatic renal cell carcinoma who had received cytokine therapy. DNA obtained from these patients was used for high resolution typing of HLA A, B, C, DRB1, DQA1 and DQB1 alleles. RESULTS: The class II alleles from patients with prolonged disease-free survival were predominantly composed of haplotype DRB1*0301/DQA1*0501/DQB1*0201 and DRB1*1501/DQA1*0102/DQB1*0602. The frequency of heterozygosity or homozygosity for these alleles was significantly greater in the good outcome group of patients than in those whose disease progressed during therapy. Heterozygosity or homozygosity at these loci was also associated with significant prolongation of survival. CONCLUSIONS: We conclude that heterozygosity or homozygosity for the class II haplotypes DRB1*0301/DQA1*0501/DQB1*0201 and DRB1*1501/DQA1*0102/DQB1*0602 is associated with durable response and survival in patients with metastatic renal cell carcinoma treated with cytokine therapy.     

Stepwise or linear decrease in penetrance of type 1 diabetes with lower-risk HLA genotypes over the past 40 years

OBJECTIVE

The objective of this study was to test if the proportion of new-onset diabetic subjects with the HLA-DR3/4-DQB1*0302 genotype is decreasing over time.

RESEARCH DESIGN AND METHODS

We analyzed HLA class II genotype frequencies over time in two large populations with type 1 diabetes diagnosed at ≤18 years of age. There were 4,075 subjects from the Type 1 Diabetes Genetics Consortium (T1DGC) and 1,675 subjects from the Barbara Davis Center (BDC).

RESULTS

Both T1DGC and BDC cohorts showed a decrease of the highest-risk HLA-DR3/4-DQB1*0302 genotype over time. This decrease was greatest over time in T1DGC subjects with age of onset ≤5 years (P = 0.004) and onset between ages 6 and 10 years (P = 0.002). The overall percent of HLA-DR3/4-DQB1*0302 was greater in the T1DGC population compared with the BDC population. There was an increased percent over time of other HLA genotypes without HLA-DR3 or -DR4 in T1DGC new onsets (P = 0.003), and the trend was similar in BDC subjects (P = 0.08). Analyzing time trend, there appears to be a large stepwise decrease in percent DR3/4 in the 1980s in T1DGC subjects with onset age <5 years (P = 0.0001).

CONCLUSIONS

The change in frequency of multiple different genotypes and a possible stepwise decrease in percent DR3/4 suggest a change in genetic risk factors and environmental determinants of type 1 diabetes. Larger studies are needed to confirm the changing pattern of genetic risk because a stepwise change may have direct bearing on defining critical environmental determinants of type 1 diabetes.The incidence of type 1 diabetes has been increasing worldwide by approximately 3% per year (1,2), with the highest increase occurring in young children (3,4). The major type 1 diabetes susceptibility locus maps to the HLA class II genes and accounts for 30–50% of genetic type 1 diabetes risk (5,6). Age at onset is inversely related to the frequency of high-risk HLA genotypes, with young children having the greatest proportion of HLA-DR3/4-DQB1*0302 genotype (7,8). Although 40% of Caucasians in the U.S. have an HLA-DR3 (with DQB1*0201) or -DR4 (with DQB1*0302) allele, at least one of these alleles is present in 95% of patients with type 1 diabetes. The estimated risk of developing type 1 diabetes for children in the general population who have the HLA DR3-DQB1*0201/DR4-DQB1*0302 genotype is ∼1:15–1:25 (9). Only 2.4% of the general population carries this genotype compared with 30–40% of type 1 diabetic patients. In siblings, HLA-DR3/4 heterozygosity identifies higher risk of type 1 diabetes than HLA identity (10). A combination of HLA-DR3/4 heterozygosity and HLA identity in siblings is associated with extreme diabetes risk of 55% by age 12 years in the Diabetes Autoimmunity Study in the Young (DAISY) population (11).However, as type 1 diabetes incidence increases, the percentage of those cases with high-risk HLA genotype is decreasing (12). A study from the U.K. (13) compared two cohorts and found a decrease in the high-risk HLA-DR3/4-DQB1*0302 genotype from 47% (Golden Years cohort diagnosed more than 50 years ago) to 35% in the more recently diagnosed cohort (between 1985–2002). Hermann et al. (8) reported a similar decrease in high-risk HLA genotypes over time (from 25 to 18%), although both of these studies (8,13) compared contemporary subjects with selective cohorts of surviving adults with childhood-onset type 1 diabetes. A study from Australia by Fourlanos et al. (14) with continuous information available reports a decrease in the high-risk HLA genotype from 79% in 1950–1969 to 28% in 2000–2005 in 462 subjects diagnosed before age 18 years; the authors conclude that the rising incidence of type 1 diabetes in childhood is accounted for by cases with lower-risk HLA genotypes.In this study, we analyze HLA class II allele frequencies over a time period ranging from 1965 to 2008 in two large populations of type 1 diabetic subjects diagnosed at age ≤18 years and describe a possible stepwise decrease in percent DR3/4.     

Susceptibility to IDDM in a Chinese population. Role of HLA class II alleles.

MHC associations with IDDM in a Chinese population were studied to investigate genetic susceptibility to the disorder. The frequency of HLA-DR3 was significantly higher in the diabetic patients (19/49 [38.7%] vs. control subjects, 11/105 [10.5%], Pc less than 1.3 x 10(-3), RR = 5.3 [CI 2.3-12.1]), whereas DR4 was not (11/49 [22.4%] vs. 28/105 [26.7%], NS). The frequency of DR3/4 heterozygosity was higher in the diabetic patients (6/49 [12.2%] vs. control subjects, 0/105 [0%], P = 1.7 x 10(-3), RR = 31.5 [CI 3.8-263.6]). The frequency of DR3/9 heterozygosity also was higher in the diabetic patients (6/49 [12.2%] vs. control subjects, 2/105 [1.9%], P = 0.03, RR = 6.2 [CI 3.0-12.7]). No significant associations were noted between DQB1 alleles and IDDM. Among DR4-positive subjects, the frequency of DQB1 allele DQB1*0302 was higher in the diabetic patients (10/11 [90.0%] vs. control subjects, 12/24 [50%], Pc less than 0.05, RR = 7.0 [CI 1.3-38.0]), and the frequency of DQB1*0401 was significantly lower in the diabetic patients (2/11 [18.2%] vs. control subjects, 16/24 [66.7%], Pc = 0.04, RR = 0.1 [CI 0.02-0.46]). No DR4 subtype was associated significantly with IDDM. The frequency of DQA1*0501, a DQA1 allele, was higher in diabetic patients (22/41 [53.7%] vs. control subjects, 20/95 [21.1%], Pc less than 3 x 10(-3), RR = 4.3 [CI 2.0-9.3]). The frequency of DQA1*0301, which has been associated consistently with IDDM in other ethnic groups, was not significantly higher in the diabetic patients in this study (27/41 [65.9%] vs. control subjects, 53/95 [55.8%], NS).(ABSTRACT TRUNCATED AT 250 WORDS)     

Genetic markers, humoral autoimmunity, and prediction of type 1 diabetes in siblings of affected children. Childhood Diabetes in Finland Study Group

The relationships between genetic markers and disease-associated autoantibodies were studied in an unselected population of 701 siblings of children with type 1 diabetes, and the predictive characteristics of these markers over a period of 9 years were determined. Increased prevalences of all the antibodies were closely associated with HLA identity to the index case, the DR4 and DQB1*0302 alleles, and the DR3/4 phenotype and the DQB1*02/0302 genotype. Antibodies to GAD (GADA) were also associated with the DR3 and DQB1*02 alleles. Siblings carrying the protective DR2 and DQB1*0602-3 alleles were characterized by lower frequencies of islet cell antibodies (ICA), antibodies to IA-2 (IA-2A), and GADA. Higher levels of ICA were related to HLA identity, the DR4 and DQB1*0302 alleles, and the susceptible DQB1 genotypes, while no significant differences were observed in the levels of IA-2A, GADA, or insulin autoantibodies among siblings with different HLA risk markers. The DR2 or DQB1*0602-3 alleles were not related to the levels of any antibody specificity. A combination of the genetic markers and autoantibodies increased the positive predictive values of all autoantibodies substantially, which may have clinical implications when evaluating the risk of developing type 1 diabetes at the individual level or when recruiting high-risk individuals for intervention trials. However, because such combinations also resulted in reduced sensitivity, autoantibodies alone rather than in combination with genetic markers are recommended as the first-line screening in siblings. Finally, not all siblings with a broad humoral autoimmune response or high-risk genetic markers present with type 1 diabetes, while some with a low genetic risk and weak initial signs of humoral autoimmunity may progress to disease.     

The HLA class II locus DPB1 can influence susceptibility to type 1 diabetes

HLA-DPB1 genotypes were determined for samples from 269 multiplex Caucasian families from the Human Biological Data Interchange. DRB1 and DQB1 loci were also characterized, allowing assignment of DPB1 alleles to haplotypes and calculation of linkage disequilibrium values. Frequencies for several DPB1 alleles differed significantly between patients and affected family-based control subjects. Some differences were attributable to linkage disequilibrium with DR and DQ alleles, whereas others were not. DPB1*0301 and DPB1*0202 alleles are predisposing for type 1 diabetes in these data, not only in analyses of individual alleles, but also in genotype analyses. DPB1*0402 appears protective; however, stratification analysis indicates that its protective effect is specific for DR3 haplotypes. A protective role for DPB1*0401 is suggested by genotype analysis. For increased statistical power, DPB1 alleles were pooled into three categories: susceptible, neutral, and protective after removal of effects due to linkage disequilibrium with DR-DQ. Analysis of these pools suggests that DPB1 primarily affects susceptibility to, rather than protection from, type 1 diabetes in a dominant fashion. This effect is more apparent in patients with genotypes other than the highest risk DR3/DR4-DQB1*0302 genotype. These data support a role for the DPB1 locus in conferring susceptibility to type 1 diabetes.     

Two single nucleotide polymorphisms identify the highest-risk diabetes HLA genotype: potential for rapid screening

OBJECTIVE—People with the HLA genotype DRB1*0301-DQA1*0501-DQB1*0201/DRB1*04-DQA1*0301-DQB1*0302 (DR3/4-DQ8) are at the highest risk of developing type 1 diabetes. We sought to find an inexpensive, rapid test to identify DR3/4-DQ8 subjects using two single nucleotide polymorphisms (SNPs).RESEARCH DESIGN AND METHODS—SNPs rs2040410 and rs7454108 were associated with DR3-DQB1*0201 and DR4-DQB1*0302. We correlated these SNPs with HLA genotypes and with publicly available data on 5,019 subjects from the Type 1 Diabetes Genetic Consortium (T1DGC). Additionally, we analyzed these SNPs in samples from 143 HLA-typed children who participated in the Diabetes Autoimmunity Study of the Young (DAISY) using Taqman probes (rs7454108) and restriction digest analysis (rs2040410).RESULTS—With a simple combinatorial rule, the SNPs of interest identified the presence or absence of the DR3/4-DQ8 genotype. A wide variety of genotypes were tested for both SNPs. In T1DGC samples, the two SNPs were 98.5% (1,173 of 1,191) sensitive and 99.7% (3,815 of 3,828) specific for DR3/4-DQ8. In the DAISY population, the test was 100% (69 of 69) sensitive and 100% (74 of 74) specific. Overall, the sensitivity and specificity for the test were 98.57 and 99.67%, respectively.CONCLUSIONS—A two-SNP screening test can identify the highest risk heterozygous genotype for type 1 diabetes in a time- and cost-effective manner.We have the ability to identify subjects with a greater than 50% risk of developing anti-islet autoimmunity and type 1 diabetes on the basis of family history and HLA genotype (1,2). Siblings with the highest type 1 diabetes risk HLA genotype DRB1*0301-DQA1*0501-DQB1*0201/DRB1*04-DQA1*0301-DQB1*0302 (DR3/4-DQ8) who are identical by descent for the major histocompatibility complex region with a type 1 diabetic sibling have an 85% risk of developing diabetes-related autoimmunity by age 15 years and a 55% risk of developing type 1 diabetes by age 12 years (1). Children with multiple first-degree relatives with type 1 diabetes and high–or moderate–diabetes risk HLA genotypes are reported to have a 50% risk for the development of multiple diabetes-related autoantibodies and type 1 diabetes (2).Prevention trials, including the Trial to Reduce Type 1 Diabetes in the Genetically at Risk (TRIGR) (3), the Nutritional Intervention to Prevent Diabetes (NIP-Diabetes) trial (4), and the Primary Oral and Intranasal Trial (Pre-POINT) are currently underway in genetically at-risk children. Many of these trials include first-degree relatives of people with diabetes as well as individuals with high-risk HLA genotypes, including DR3/4-DQ8. The identification of subjects for these trials requires large-scale HLA screening, with many children tested who do not have the highest type 1 diabetes risk. Current typing techniques for DR3/4-DQ8 often utilize coamplification of the DQA1 and DQB1 genes followed by multiple probe hybridization or direct sequencing. This technique uses sequence-specific oligonucleotides in a linear assay for hybridization with amplified product from DNA samples (5). Alleles are called with a customized typing program. Sequence-based typing techniques use PCR to amplify DRB1 genes that are sequenced, with HLA type determined using special software (6). High-throughput screening systems that employ asymmetric PCR and hybridization of allele-specific probes as a first screening step to identify samples with specified HLA genotypes have been developed. Samples identified via these programs can be identified for further HLA genotyping (7). This method is cost and time consuming, as it may cost up to $31.44 to genotype 1 sample and takes up to 9 h to perform and analyze a set of 50 samples.Several studies have examined the possibility of predicting HLA alleles from existing single nucleotide polymorphism (SNP) data (8–10); however, only one article has provided data on predicting specific HLA alleles from individual SNPs. de Bakker et al. (8) reported an association between HLA types and SNPs. SNP rs2040410 A allele was associated with DRB1*0301, and rs7454108 C allele with DQB1*0302. We have developed and tested the ability of these two SNPs to identify individuals with the DR3/4-DQ8 genotype in subjects within the Type 1 Diabetes Genetics Consortium (T1DGC) and the Diabetes Autoimmunity Study in the Young (DAISY). This novel method adds to existing knowledge by utilizing SNP technology to quickly identify individuals with the DR3/4-DQ8 genotype and may be beneficial to prevention trials because it provides high-throughput screening in a time- and cost-effective manner.     

Report of recombinations between HLA loci within two families: utility of high resolution typing

We have analysed two Caucasian families in which recombinant individuals have been identified. In both families, initial low resolution typing of class I and II antigens of possible patients referred for bone marrow transplantation and their respective potential donors (based on inherited haplotypes analysis) revealed them to be HLA identical and supposedly inheriting-non-recombinant haplotypes. The mothers were found to be DRB1*04 generic allele homozygous, but possessing two DRB1*04 specific alleles, DRB1*0403 and DRB1*0404 (family A) and DRB1*0401 and DRB1*0402 (family B). In both cases the patients inherited a maternal haplotype that is the result of a recombination event between the mother's HLA-DRB1 and -B genes on their chromosomes. Based on linkage disequilibrium it is likely that the recombinant haplotypes are present in the patients rather than their brothers. In both families, the results of the MLC in terms of relative response was positive. Thus, these cases illustrate the importance of high resolution DNA class II typing when assignment of MHC antigens is of extreme importance (i.e. bone marrow transplantation).     

Recognition of HLA class I-restricted beta-cell epitopes in type 1 diabetes

Type 1 diabetes results from the autoimmune destruction of insulin-producing pancreatic beta-cells by cytotoxic T-lymphocytes (CTLs). In humans, few beta-cell epitopes have been reported, thereby limiting the study of beta-cell-specific CTLs in type 1 diabetes. To identify additional epitopes, HLA class I peptide affinity algorithms were used to identify a panel of peptides derived from the beta-cell proteins islet amyloid polypeptide (IAPP), islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGRP), insulin, insulinoma-associated antigen 2 (IA-2), and phogrin that were predicted to bind HLA-A*0201. Peripheral blood mononuclear cells from 24 HLA-A*0201 recent-onset type 1 diabetic patients and 11 nondiabetic control subjects were evaluated for gamma-interferon secretion in response to peptide stimulation in enzyme-linked immunospot assays. We identified peptides IAPP9-17, IGRP215-223, IGRP152-160, islet IA-2(172-180), and IA-2(482-490) as novel HLA-A*0201-restricted T-cell epitopes in type 1 diabetic patients. Interestingly, we observed a strong inverse correlation between the binding affinity of beta-cell peptides to HLA-A*0201 and CTL responses against those peptides in recent-onset type 1 diabetic patients. In addition, we found that self-reactive CTLs with specificity for an insulin peptide are frequently present in healthy individuals. These data suggest that many beta-cell epitopes are recognized by CTLs in recent-onset type 1 diabetic patients. These epitopes may be important in the pathogenesis of type 1 diabetes.     

Identification of Novel HLA-A*0201-restricted epitopes in recent-onset type 1 diabetic subjects and antibody-positive relatives

Cytotoxic T-lymphocytes (CTLs) are considered to be essential for beta-cell destruction in type 1 diabetes. However, few islet-associated peptides have been demonstrated to activate autoreactive CTLs from type 1 diabetic subjects. In an effort to identify novel epitopes, we used matrix-assisted algorithms to predict peptides of glial fibrillary acidic protein (GFAP), prepro-islet amyloid polypeptide (ppIAPP), and islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGRP) that likely bind to HLA-A*0201 with a strong affinity and contain a COOH-terminal proteasomal cleavage site. Seven peptides stabilized HLA-A*0201 expression in binding assays and were used to stimulate peripheral blood mononuclear cells and were evaluated for granzyme B secretion. We found that 5 of 13 type 1 diabetic subjects and 4 of 6 antibody-positive relatives exhibited greater numbers of granzyme B-secreting cells in response to at least one putative epitope compared with healthy control subjects. The most prevalent responses in antibody-positive and type 1 diabetic subjects were to ppIAPP(9-17). Other peptides recognized by type 1 diabetic or antibody-positive subjects included GFAP(143-151), IGRP(152-160), and GFAP(214-222). These data implicate peptides of ppIAPP, GFAP, and IGRP as CTL epitopes for a heterogenous CD8(+) T-cell response in type 1 subjects and antibody-positive relatives.     

Asian-specific HLA haplotypes reveal heterogeneity of the contribution of HLA-DR and -DQ haplotypes to susceptibility to type 1 diabetes.

To assess the effect of Asian-specific HLA haplotypes on susceptibility to type 1 diabetes, we investigated the association of genotypic combinations of DRB1-DQB1 haplotypes with susceptibility to type 1 diabetes. We studied 132 Japanese patients with type 1 diabetes and 157 control subjects, along with 67 Korean patients and 109 control subjects. DRB1*0405-DQB1*0401 and DRB1*0901-DQB1*0303 were confirmed to be two major susceptible HLA haplotypes in the Japanese population. The frequencies of heterozygotes and homozygotes with DRB1*0405-DQB1*0401 were similarly higher in patients than in control subjects (homozygotes, 5.3% vs. 3.8%; heterozygotes, 48.5% vs. 26.1%). In contrast, homozygotes, but not heterozygotes, with DRB1*0901-DQB1*0303 were more frequent in patients with type 1 diabetes than in control subjects (homozygotes, 12.9% vs. 0.6%; heterozygotes, 22.0% vs. 24.8%). A similar tendency was also observed in the Korean population. In multiple logistic regression analysis, DRB1*0405-DQB1*0401 fitted a dominant model and DRB1*0901-DQB1*0303 fitted a recessive model. These data, which indicate that the contribution of HLA haplotypes to the genetic susceptibility to type 1 diabetes differs depending on the genotypic combination of HLA haplotypes, suggest the importance of extensive analysis of genotypes in studies on HLA and disease association in general.     

HLA-DQB1* alleles and genetic susceptibility to type 1 diabetes mellitus

AIM: To determine human leukocyte antigen (HLA)DQB1 allele association with susceptibility to type 1 diabetes (T1D) and to clinical and laboratory findings. METHODS: This study was conducted on 85 unrelated Egyptian children with T1D recruited consecutively from the Pediatric Diabetes Endocrinology outpatients Clinic; Mansoura University Children’s Hospital, Egypt. Patient mean follow up period was 2.5 years. Patients were subdivided according to level of HbA1c (optimal/suboptimal control < 8.5% and poor control ≥ 8.5%). Thecontrol group consisted of 113 unrelated ageand sexmatched healthy subjects without T1D or other autoimmune diseases. Genomic DNA extraction was done for all subjects using a DNA isolation kit. HLA-Class Ⅱ-DQB1 allele typing was carried out with a polymerase chain reaction-sequence-specific oligonucleotide probe using a INNO-LiPA HLA-DQB1 update kit. RESULTS: Significant differences were detected between Egyptian patients with T1D and control groups in the frequencies of DQB1*02 [44.4% vs 18.6%, corrected P value (Pc) < 0.001] and DQB1*03 (41.2% vs 24.4%, Pc < 0.001). Significant differences were also observed between control groups and T1D patients in the frequencies of DQB1*05 (14.6% vs 7.2%, P = 0.029) and DQB1*06 (34.1% vs 7.2%, P < 0.001). However, after correction for multiple comparisons, the significance was retained for HLA-DQB1*06 (Pc < 0.001) but lost for HLA-DQB1*05. HLA-DQB1*0201, *0202, *030201 were positively associated with T1D (Pc = 0.014, Pc < 0.001, and Pc < 0.001 respectively), while HLA-DQB1*060101 was negatively associated (Pc < 0.001) with the condition. Although the HLA-DQB1 alleles 030101 and 050101 were significantly higher in controls (P = 0.016, P = 0.025 respectively), both of them lost statistical significance after correction of P value. The frequency of the HLA-DQB1 genotypes 02/02, 02/03, and 03/03 was higher in T1D patients, and the frequency of the genotypes 03/06, 05/06, and 06/06 was higher in controls, these differences being statistically significant before correction. After correction, the genotypes 02/02, 02/03 in T1D, and the genotypes 03/06, 06/06 in controls were still significant (Pc = 0.01, Pc < 0.001, Pc < 0.001, and Pc = 0.04, respectively). Non-significant associations were found between the frequency HLA-DQB1 alleles and genotypes in T1D in relation to the grade of diabetic control, Microalbuminuria, age, gender, age of presentation, weight, height, frequency of diabetic ketoacidosis (P =0.42), serum cholesterol, and fasting and post-prandial level of C-peptide (P = 0.83, P = 0.9, respectively). CONCLUSION: The Current work suggests that HLADQB1 alleles *030201, *0202, *0201, and genotypes 02/03, 02/02 may be susceptibility risk factors for development of T1D in Egyptian children, while the HLADQB1*060101 allele, and 03/06, 06/06 genotypes may be protective factors. HLA-DQB1 alleles and genotypes do not contribute to microalbuminuria or grade of diabetic control.     

Association of HLA-DQA1*03011-DQB1*0301 haplotype with the development of respiratory scleroma.

OBJECTIVE: Respiratory scleroma (RS) is a progressive, chronic, granulomatous disease caused by Klebsiella rhinoscleromatis. There is only one report of RS association with HLA-DQ3. In this study, molecular association of HLA class II and RS was determined. STUDY DESIGN AND SETTING: Nine RS patients and 163 healthy controls were compared. DQA1, DQB1, and DRB1 loci were typed. RESULTS: Statistical analysis demonstrated association between DQB1*0301 and susceptibility to RS (P(c) = 0.004). Haplotype analysis showed an association of DQA1*03011-DQB1*0301 (P = 1.21E-19) and DRB1*0407-DQA1*03011-DQB1*0301 (P = 0.0002). CONCLUSIONS: Results established that DQA1*03011-DQB1*0301 haplotype is a strong risk factor for development of RS.     

HLA class I and II in black children with hepatitis B virus-associated membranous nephropathy

BACKGROUND: The pathogenetic mechanisms by which individuals with chronic hepatitis B virus (HBV) infection develop membranous nephropathy (MN) are probably dependent on interactions between viral, host and environmental factors; some evidence suggests a genetic predisposition. HBVMN constitutes a major etiological group in black children with nephrotic syndrome. We therefore explored the HLA associations in black children with HBVMN. METHOD: Thirty black children, age range 2 to 16 years, with biopsy-proven HBVMN, were the subjects of the study. HBV status was determined using third generation ELISA. HLA A, B and C antigens were determined using a two-stage lymphocytotoxic test. HLA DRB1* and DQB1* typing was done using sequence-specific primers. HLA class 1 and II antigen frequencies of the study subjects were compared to controls that were randomly chosen healthy blood donors from the same population. RESULTS: HLA DQB1*0603 was increased in patients with HBVMN compared to controls (chi2 = 13.65, RR = 4.3). DRB1*07 and DQB1*02 were increased in frequency in the study subjects but failed to reach statistical significance. There was no significant difference in the frequencies of class 1 antigens in the study group compared to controls. CONCLUSION: To our knowledge, this is the first report of HLA associations in black patients with HBVMN in whom Class 1 and 11 antigens were determined using molecular methodology. There was a high frequency of DQB1*0603 in subjects compared to controls, suggesting a possible genetic predisposition to the development of HBVMN.     

Next-Generation Sequencing Reveals That HLA-DRB3, -DRB4, and -DRB5 May Be Associated With Islet Autoantibodies and Risk for Childhood Type 1 Diabetes

The possible contribution of HLA-DRB3, -DRB4, and -DRB5 alleles to type 1 diabetes risk and to insulin autoantibody (IAA), GAD65 (GAD autoantibody [GADA]), IA-2 antigen (IA-2A), or ZnT8 against either of the three amino acid variants R, W, or Q at position 325 (ZnT8RA, ZnT8WA, and ZnT8QA, respectively) at clinical diagnosis is unclear. Next-generation sequencing (NGS) was used to determine all DRB alleles in consecutively diagnosed patients ages 1–18 years with islet autoantibody–positive type 1 diabetes (n = 970) and control subjects (n = 448). DRB3, DRB4, or DRB5 alleles were tested for an association with the risk of DRB1 for autoantibodies, type 1 diabetes, or both. The association between type 1 diabetes and DRB1*03:01:01 was affected by DRB3*01:01:02 and DRB3*02:02:01. These DRB3 alleles were associated positively with GADA but negatively with ZnT8WA, IA-2A, and IAA. The negative association between type 1 diabetes and DRB1*13:01:01 was affected by DRB3*01:01:02 to increase the risk and by DRB3*02:02:01 to maintain a negative association. DRB4*01:03:01 was strongly associated with type 1 diabetes (P = 10⁻³⁶), yet its association was extensively affected by DRB1 alleles from protective (DRB1*04:03:01) to high (DRB1*04:01:01) risk, but its association with DRB1*04:05:01 decreased the risk. HLA-DRB3, -DRB4, and -DRB5 affect type 1 diabetes risk and islet autoantibodies. HLA typing with NGS should prove useful to select participants for prevention or intervention trials.     

Do the HLA-DQ and DP genes play a role in rheumatoid arthritis?

Whereas the DRB1 alleles have well-established associations with rheumatoid arthritis (RA), the DQ and DP alleles are of more controversial relevance to RA. Early studies of the DQB1 genes in RA determined the frequencies of the two DQB1*03 subtypes that are in linkage disequilibrium with DR4, DQB1*0301 (DQw7) and *0302 (DQw8). Their results are conflicting and difficult to interpret because molecular biology techniques for determining DR4 specificity polymorphism were not available at the time. None of the more recent studies found compelling evidence that the DQB1 alleles influenced the susceptibility to RA. A few studies suggest that the DQ alleles may influence the clinical or biological expression of the disease, perhaps through a complementary effect of the DRB1 and DQB1 alleles. DR-DQ complementarity has been demonstrated in the DQ8 transgenic mouse model, although this is not necessarily relevant to the human disease. The role of DPB1 remains hypothetical but may involve an influence of some alleles in relatively mild forms of RA. The DQB1 and DPB1 alleles are in strong linkage disequilibrium with the DRB1 alleles, making the elucidation of their independent effects a challenging task. Studies are needed to determine whether these linkage disequilibriums can influence the development of autoimmune diseases.