The HLA-DR3,DQ2 Heterozygous Genotype is Associated with an Accelerated Progression of Primary Sclerosing Cholangitis

Background: An improvement of prognostic models in primary sclerosing cholangitis (PSC) is needed. In particular, inclusion of prognostic markers that are independent of the disease stage would be advantageous. We investigated whether HLA class II genes associated with PSC are also related to disease progression. Methods: The study included 265 PSC patients from five European countries with a median follow-up of 9.1 years. The end-points were death (n = 38) or liver transplantation (n = 52). Thirty patients developed cholangiocarcinoma during follow-up. Results: The DRB1*03,DQA1*0501,DQB1*02 (i.e. DR3,DQ2) heterozygous genotype was associated with an increased risk of death or liver transplantation (hazard ratio = 1.63; 95% confidence interval (CI) = 1.06-2.52). The presence of a DQ6 encoding haplotype (DQB1*0603 or DQB1*0602) in DR3,DQ2 negative individuals was associated with a reduced risk of death or liver transplantation (hazard ratio = 0.57; 95% CI = 0.36-0.88). There was a trend towards an increased risk of developing cholangiocarcinoma among DR4,DQ8 positive patients, but this did not reach significance (odds ratio = 2.27; 95% CI = 0.78-6.62). Conclusion: The DR3,DQ2 heterozygous genotype is associated with a more rapid progression of PSC, whereas HLA-DQ6 is associated with a retarded disease progression. It is possible that the DR4,DQ8 haplotype is related to cholangiocarcinoma development.     

Extreme genetic risk for type 1A diabetes

Type 1A diabetes (T1D) is an autoimmune disorder the risk of which is increased by specific HLA DR/DQ alleles [e.g., DRB1*03-DQB1*0201 (DR3) or DRB1*04-DQB1*0302 (DR4)]. The genotype associated with the highest risk for T1D is the DR3/4-DQ8 (DQ8 is DQA1*0301, DQB1*0302) heterozygous genotype. We determined HLA-DR and -DQ genotypes at birth and analyzed DR3/4-DQ8 siblings of patients with T1D for identical-by-descent HLA haplotype sharing (the number of haplotypes inherited in common between siblings). The children were clinically followed with prospective measurement of anti-islet autoimmunity and for progression to T1D. Risk for islet autoimmunity dramatically increased in DR3/4-DQ8 siblings who shared both HLA haplotypes with their diabetic proband sibling (63% by age 7, and 85% by age 15) compared with siblings who did not share both HLA haplotypes with their diabetic proband sibling (20% by age 15, P < 0.01). 55% sharing both HLA haplotypes developed diabetes by age 12 versus 5% sharing zero or one haplotype (P = 0.03). Despite sharing both HLA haplotypes with their proband, siblings without the HLA DR3/4-DQ8 genotype had only a 25% risk for T1D by age 12. The risk for T1D in the DR3/4-DQ8 siblings sharing both HLA haplotypes with their proband is remarkable for a complex genetic disorder and provides evidence that T1D is inherited with HLA-DR/DQ alleles and additional MHC-linked genes both determining major risk. A subset of siblings at extremely high risk for T1D can now be identified at birth for trials to prevent islet autoimmunity.     

Influence of human leukocyte antigen class II alleles on susceptibility to Entamoeba histolytica infection in Bangladeshi children

BACKGROUND: The association of antibody responses with both innate and acquired immunity to amebiasis indicate that CD4+ T cells play a role in protection against Entamoeba histolytica infection. To test this hypothesis, we compared the genotype frequencies of human leukocyte antigen (HLA) class II alleles in a cohort of Bangladeshi children intensively monitored for E. histolytica infection for a 3-year period. METHODS: Using logistic regression, we calculated the odds of disease by genotype and by haplotype. RESULTS: The DQB1*0601 heterozygous and homozygous genotypes were found in 55% of E. histolytica-negative children but in only 34% of E. histolytica-positive children (overall odds ratio, 2.39; 95% confidence interval [CI], 1.26-4.54). Children who were heterozygous for the DQB1*0601/DRB1*1501 haplotype were 10.1 times (95% CI, 2.02-50.6) more likely to be both E. histolytica negative and serum anti-lectin immunoglobulin G negative at baseline. Other DQB1 and DRB1 alleles (DQB1*0202, DQB1*0301, and DRB1*0701) were not associated with any of the clinical outcomes related to amebiasis. CONCLUSION: A potential protective association was observed with the HLA class II allele DQB1*0601 and the heterozygous haplotype DQB1*0601/DRB1*1501. This association may explain why amebiasis does not occur in some children who are exposed to the parasite and implicates HLA class II-restricted immune responses in protection against E. histolytica infection.     

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.     

MHC class I chain related gene A (MICA) modulates the development of coeliac disease in patients with the high risk heterodimer DQA1*0501/DQB1*0201

BACKGROUND AND AIMS: Coeliac disease (CD) is an enteropathic disorder characterised by a strong association with major histocompatibility complex (MHC) heterodimer HLA-DQ2. It has been suggested that other HLA class I genes in combination with DQ may also contribute to CD susceptibility. The aim of this study was to investigate whether other candidate genes modify the risk of developing different clinical forms of CD. PATIENTS AND METHODS: We studied 133 Spanish coeliac patients, divided according to their clinical presentation into typical and atypical groups, and 116 healthy controls. All were typed by polymerase chain reaction-sequence specific primers (PCR-SSP) at HLA-B, DRB1, DQA1, and DQB1 loci and for exon 5 of the MHC class I chain related gene A (MICA). RESULTS: No differences were found in the frequency of the DQA1*0501/DQB1*0201 heterodimer in either group. The risk of typical CD was significantly associated with the DR7/DQ2 haplotype (p(c)=0.02, odds ratio (OR)=3.4, ethiological fraction (EF)=0.4). Extended haplotype (EH) 8.1 (B8/DR3/DQ2) was found to be overrepresented in the atypical form compared with the typical form (p(c)=0.001, OR=4.19, EF=0.56). The trinucleotide repeat polymorphism MICA-A5.1 was found to be increased in the atypical group of patients compared with the typical group (p(c)=0.00006, OR=8.63, EF=0.81). This association was independent of linkage disequilibrium with EH8.1 as this was also found to be increased in EH8.1 negative atypical patients compared with the typical group (p(c)=0.004, OR=6.66, EF=0.56). CONCLUSIONS: Our results showed that the risk of developing typical forms of CD was associated with DR7/DQ2 haplotype, and the presence of B8/DR3/DQ2 was significantly increased in atypical patients. In these, the MICA-A5.1 allele confers an additive effect to the DR3/DQ2 haplotype that may modulate the development of CD.     

汉族类风湿关节炎患者HLA—DR和—DQ基因分型研究

为探讨ＨＬＡ－ＤＲ和－ＤＱ等位基因与我国汉族类风湿关节炎（ＲＡ）的相关性，采用聚合酶链反应－限制性内切酶片段长度多态性分析（ＰＣＲ－ＲＦＬＰ）方法对汉族人群中３５例ＲＡ患者和１００名健康人的ＤＲ和ＤＱ位点进行ＤＮＡ定型分析。结果发现，ＤＲ４频率在正常人为２４．０％，在ＲＡ患者为５１．４％（Ｐ＜０．０１，ＲＲ＝３．３０）；ＤＲ４亚型位点分析发现２组均以ＤＲＢ１＊０４０５占多数，但ＤＲＢ１＊０４０５频率在ＲＡ组为３１．４％，高于正常人的１０．０％（Ｐ＜０．０１）。ＤＱ４频率在全部ＲＡ患者为３７．１％，在ＤＲ＋４ＲＡ患者为７２．２％，均高于全部正常人的１０．０％（Ｐ＜０．０１）和ＤＲ＋４正常人的４１．６％（Ｐ＝０．０３７６）；ＤＲ＋４－ＤＱ＋４ＲＡ患者的病情重于ＤＲ－４患者。结果提示，ＤＲ４、主要是ＤＲＢ１＊０４０５与ＲＡ相关，ＤＱ４可增加ＤＲ４对ＲＡ的易感性，ＤＲ＋４－ＤＱ＋４单倍型是ＲＡ病情严重程度的标志。     

中国人群1型糖尿病HLA-DQ基因多态性的Meta分析

目的　综合评价中国人群HLA DQ基因多态性与 1型糖尿病 (DM)的关联性。方法　以 1型DM组和健康对照组的各HLA DQ等位基因频数(基因型频数、单倍型频数 )分布的OR值为统计量,全面检索相关文献;应用Meta分析软件包REVMAN4. 2,在基因分型水平上,对各研究的结果进行一致性检验和数据合并,并评估发表偏倚。结果　等位基因DQA1* 0301、DQA1* 0501、DQB1* 0201、DQB1* 0303、DQB1* 0401和DQB1* 0604是中国人群 1型DM的危险基因 (均P<0. 05), 他们的合并OR值分别为2. 83、2. 90、4. 17、1. 65、2. 00和 3. 00;基因型 (或单倍型 )DQA1* 0301 /DQB1* 0201、DQA1* 0301 /DQB1*0302、DQA1* 0501 /DQB1* 0201、DQA1* 0301 /DQB1* 0201 /DRB1* 0301和DQB1* 0302 /DRB1* 0405是中国人群 1型DM的危险基因型(或单倍型,均P<0. 05),他们的合并OR值分别为 8. 95、3. 09、6. 01、6. 57和 14. 85。而等位基因DQA1* 0101、DQA1* 0102、DQA1* 0103、DQA1* 0104、DQA1* 0201、DQA1* 0401、DQA1* 0601、DQB1* 0301、DQB1* 0501、DQB1* 0503、DQB1* 0601和DQB1* 0602是中国人群 1型DM的保护等位基因(均P<0. 05),他们的合并OR值分别为 0. 47、0. 38、0. 21、0. 07、0. 44、0. 39、0. 44、0. 19、0. 33、0. 32、0. 42和 0. 28; 基因型     

HLA class II favors clearance of HCV infection and progression of the chronic liver damage

BACKGROUND/AIMS: This study was aimed to determine whether host-dependent genetic factors modulate the outcome of HCV infection. METHODS: HLA class II DRB and DQB typing was performed in 184 infected patients and 200 healthy volunteers. Among the patients, 149 subjects had persistent HCV viremia (Group 1) and 35 subjects underwent spontaneous viral clearance (Group 2). Group 1 included cirrhotic patients with transfusion-acquired infections (n = 79), asymptomatic HCV carriers (n = 42), and patients with chronic hepatitis C responsive to interferon therapy (n = 28). RESULTS: Spontaneous viral clearance was associated with HLA DRB1*1104 (pc = 0.054, OR = 4.51, 95% C.I. 2.02-10.1) and HLA DQB1*0301 (pc = 0.0039, OR = 4.52, 95% C.I. 2.15-9.51). In Group 1 the haplotype DRB1*1104/DQB1*0301 was less frequent (4.8%) than in Group 2 (18.3%) (pc = 0.009, OR = 7.38, 95% C.I. 2.58-21.59). At the HLA level, cirrhotic patients were not different from asymptomatic HCV carriers and patients with interferon-induced viral clearance. In cirrhotic patients infected with genotype 1b, the DQB1*0502 allele was more frequently found in those with rapidly progressive liver damage (OR = 8.15, 95% C.I. 1.49-44.44), but the corrected p-value was not significant (pc = 0.09). CONCLUSIONS: The HLA haplotype DRB1*1104/DQB1*0301 appears to contribute to the spontaneous clearance of HCV infection. The predominance of the DQB1*0502 allele in cirrhotic patients with a rapidly progressive disease possibly reflects an influence of this allele on the progression of the HCV-related liver disease.     

Analysis by the polymerase chain reaction of histocompatibility leucocyte antigen-DR9-linked susceptibility to insulin-dependent diabetes mellitus.

DNA sequence analysis of class II HLA from Caucasian and black patients with type 1 (insulin-dependent) diabetes mellitus has suggested that aspartic acid at position 57 (Asp 57) of the DQ beta chain provides protection against insulin-dependent diabetes mellitus (IDDM). In contrast, most Japanese patients with IDDM have Asp 57-positive alleles. To determine the reason for the differences and to localize the HLA-linked diabetogenic gene in Japanese, we studied the DQA1 and DQB1 genes of Japanese patients with IDDM and control subjects by the polymerase chain reaction in combination with restriction fragment length polymorphism analysis. Associations of DQA1*0301 and DQB1*0303 with IDDM were observed. DQA1*01 was associated negatively with IDDM. The HLA-DR9 haplotype, which is associated positively with IDDM in Japanese, was associated with DQA1*0301 and DQB1*0303, indicating that the Japanese DR9 haplotype is the same as that in caucasians but different from that in blacks. Of the loci on Japanese DR9 haplotypes, the DQA1*0301 allele showed the highest association with IDDM. DQB1*0303 was also positively associated with IDDM. Since DQB1*0303 is identical to DQB1*0302 except that it contains Asp 57, the data suggests that an Asp 57-positive allele confers susceptibility to IDDM when the whole molecule of the DQ beta chain is similar to other susceptible DQ beta chains. DQA1*0301 appears to be a marker of IDDM in all these populations: Japanese, caucasian, and black.     

HLA class II is a factor in cardiovascular morbidity and mortality rates in patients with type 1 diabetes

Aims/hypothesis

Patients with type 1 diabetes and kidney disease have a higher risk of cardiovascular events. HLA class II genes are expressed on infiltrated inflammatory cells and smooth-muscle cells in atherosclerotic plaques. We hypothesised that HLA class II haplotypes or genotypes might influence the risk of cardiovascular complications and death in Finnish type 1 diabetic patients.

Methods

We included 3,082 patients with type 1 diabetes from the Finnish Diabetic Nephropathy Study. We analysed the 12 and ten most common HLA II haplo- and genotypes, respectively, using χ ² tests. The positive findings were analysed with three differently adjusted regression models with cardiovascular morbidity and death as endpoints. Different kidney status groups were analysed separately.

Results

At baseline, the common (DR1/10)-DQB1*05:01 haplotype (20.4%) and the (DR1/10)-DQB1*05:01/DRB1*04:01-DQB1*03:02 genotype (8.7%) were independently associated with cardiovascular disease in all kidney status groups, except in patients with normal AER. At follow-up (9.45?years; range 0.1–16.1?years), the (DR1/10)-DQB1*05:01/DRB1*04:01-DQB1*03:02 genotype was associated with cardiovascular mortality rates in patients with normal AER and microalbuminuria.

Conclusions/interpretation

The (DR1/10)-DQB1*05:01 haplotype and the (DR1/10)-DQB1*05:01/DRB1*04:01-DQB1*03:02 genotype are independently associated with cardiovascular events and death in Finnish type 1 diabetic patients.     

Evidence for a protective role of the human leukocyte antigen class II region in early rheumatoid arthritis

OBJECTIVE: To analyse the distribution of predisposing DQ3 (DQB1*03(*04)/DQA1*03) and DQ5 (DQB1*0501/DQA1*01), shared epitope encoding and protective DRB1 alleles in patients with early rheumatoid arthritis (RA) and undifferentiated arthritis (UA). METHODS: Consecutive patients enrolled in an early arthritis clinic were DNA-typed for HLA-DQ and DR. RA patients (n=195), UA patients (n=160) and controls from the same region (n=306) were sorted according to their DQ-DR phenotypes: DQ3 vs DQ5 and the presence or absence of a protective DERAA-positive DRB1 molecule. The three groups were also sorted according to the shared epitope (SE) hypothesis. RESULTS: We observed the association of both DQ3 and DQ5 with RA. DQ3/3 homozygous individuals had the highest risk of developing disease [odds ratio (OR)=20.00]. Conversely DQ5, but not DQ3, was associated with undifferentiated arthritis (OR=2.15 vs 1.25). Consistent with these differences, DQ3-positive individuals had significantly more active disease at the first visit at the outpatient clinic than DQ5-positive patients. DRB1 alleles encoding a DERAA motif in their third hypervariable region provided a strong dominant protection against RA among DQ5-positive individuals and decreased arthritis activity among DQ3-positive patients. Individuals with SE-positive DR1, DR4 and DR10 alleles were also predisposed to RA, DR4/4 homozygous individuals having the highest risk of developing RA (OR=11.00). CONCLUSION: The DQ3-DR4/9 haplotypes are associated with RA. The DQ5-DR1/10 haplotypes are associated with less active disease, i.e. UA, and DERAA encoding DRB1 alleles modulate either predisposition to or the severity of RA. We propose that HLA polymorphism influences not only the initiation or perpetuation of RA but also protection against the disease.     

The MHC is a major determinant of viral status, but not fibrotic stage, in individuals infected with hepatitis C

BACKGROUND & AIMS: In hepatitis C infection, several studies have examined the role of the major histocompatibility complex (MHC) in determining outcome, with variable results. To clarify the importance of MHC, we examined class II DR and DQ antigens in a homogenous cohort of women exposed to hepatitis C genotype 1b from a single inoculum. METHODS: Of 243 participants, 95 had spontaneous viral clearance and 148 are chronically infected. The frequencies of HLA class II DR and DQ antigens were compared between the 2 groups and between liver biopsy findings of 145 chronically infected subjects. RESULTS: DRB1*0101 and DQB1*0501 alleles were more frequent in subjects who sustained viral clearance than in chronically infected subjects (32.3% and 36.8% vs. 8.8% and 14.2%, respectively; P = 0.002). DRB1*03011 and DQB1*0201 occurred more frequently in chronically infected subjects than in those who cleared the virus (41.5% and 42.6% vs. 16.7% and 15.8%, respectively; P = 0.001). Both DRB1*03011 and DQB1*0201 were significantly less frequent in those with higher inflammatory scores on liver biopsy. CONCLUSIONS: We show that in a homogenous cohort of women infected with the same hepatitis C virus, several HLA antigens are associated with either viral clearance or persistence. This suggests a strong role for host immunogenetic factors in determining outcome in hepatitis C infection.     

Association between HLA class II genes and autoantibodies to cyclic citrullinated peptides (CCPs) influences the severity of rheumatoid arthritis

OBJECTIVE: The functional role of HLA class II molecules in the pathogenesis of rheumatoid arthritis (RA) is unclear. HLA class II molecules are involved in the interaction between T and B lymphocytes required for long-lived B cell responses and generation of high-affinity IgG antibodies. We undertook this study to investigate the relationship between HLA class II gene polymorphisms and RA-specific IgG antibodies against cyclic citrullinated peptides (anti-CCP antibodies). METHODS: High-resolution HLA-DR and DQ typing and anti-CCP-2 antibody testing were performed on 268 RA patients from the Early Arthritis Clinic cohort at the Department of Rheumatology of the Leiden University Medical Center. The presence of anti-CCP antibodies was analyzed in carriers of the different DR and DQ alleles. Disease progression was measured over a period of 4 years by scoring radiographs of the hands and feet using the Sharp/van der Heijde method. RESULTS: Carriership of the individual alleles HLA-DRB1*0401, DRB1*1001, DQB1*0302, and DQB1*0501 was associated with the presence of anti-CCP antibodies. Carriers of DQ-DR genotypes containing proposed RA susceptibility alleles were significantly more often anti-CCP antibody positive. Carriership of one or two HLA-DRB1 shared epitope (SE) alleles was significantly associated with production of anti-CCP antibodies (odds ratio [OR] 3.3, 95% confidence interval [95% CI] 1.8-6.0 and OR 13.3, 95% CI 4.6-40.4, respectively). An increased rate of joint destruction was observed in SE+, anti-CCP+ patients (mean Sharp score 7.6 points per year) compared with that in SE-, anti-CCP+ patients (2.4 points per year) (P = 0.04), SE+, anti-CCP- patients (1.6 points per year) (P < 0.001), and SE-, anti-CCP- patients (1.6 points per year) (P < 0.001). CONCLUSION: HLA class II RA susceptibility alleles are associated with production of anti-CCP antibodies. Moreover, more severe disease progression is found in RA patients with both anti-CCP antibodies and SE alleles.     

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.     

Genetic susceptibility and the link between cat exposure and rheumatoid arthritis

OBJECTIVES: Rheumatoid arthritis (RA) is a chronic inflammatory disease for which immunogenetic susceptibility factors have been defined. In a recent case control study, it was shown that a prior intimate relationship with pet cats or budgerigars confers risk for subsequent development of RA after a period of latency. Pets are a potential reservoir for putative microbial agents that could be a stimulus for chronic inflammation subject to the influence of immunogenetic factors. Therefore, a study was undertaken to determine whether the presence of HLA-DRB1 alleles bearing the RA susceptibility motif influenced risk for RA associated with prior exposure to pets. METHODS: Blood samples were obtained from available RA patients and their case controls who had participated in the prior epidemiologic study. DR and DQ genotypes were determined by sequence analysis of oligonucleotides amplified from the DRB1 and DQB1 genes by polymerase chain reactions (PCR). Subjects were segregated according to pet exposure (as determined previously) and genotype for statistical analyses. RESULTS: The odds ratio (OR) for prepubertal exposure to cats and RA in available subjects irrespective of DRB1 genotype was 4.2 (CI, 2.1 to 8.5; P<.00002). The OR between prior exposure to cats and RA in subjects with the RA susceptibility genotype DRB1 *0401 and *0404 was 5.8 (CI, 1.4 to 26; P<.02) and >24 (CI, 1.6 to 813; P<.01), respectively. In subjects with the genotype DRB1 *1501, the association between RA and prior cat exposure was OR 8.4 (CI, 1.7 to 45; P<.01). No significant association between RA and pet exposure was found in patients selected according to other genotypes. The association between RA and the recognized HLA-DR susceptibility motif was slightly stronger in subjects with a history of intimate cat exposure (OR 4.7 [CI, 1.5 to 14.8], P<.005) than subjects without prior intimate exposure (OR 3.3 [CI; 1.2 to 9.3], P<.02). In the small number of subjects who had reported an intimate association with pet birds, no influence of DR genotype on risk for RA was discerned. CONCLUSIONS: Risk for RA associated with prior intimate exposure to cats is concentrated in subjects with the RA-susceptibility conferring genotypes DRB1 *0401 and *0404. The findings suggest an interaction between an environmen-tal agent associated with pet cats and certain RA susceptibility-conferring DR genotypes. The risk for RA associated with intimate cat exposure also was significant in subjects with DRB1*1501, a genotype not otherwise associated with RA, but which shares with known RA susceptibility-bearing alleles the presence of an electropositive pocket (Pocket 4) in the DR peptide binding groove.     

Racial differences in HLA class II associations with hepatitis C virus outcomes

A broad, vigorous CD4 T cell response, mediated by class II human leukocyte antigens (HLAs), favors hepatitis C virus (HCV) clearance. HLA-DQB1*0301 has been associated with viral clearance in an ethnically homogeneous cohort. To validate this association and to identify other class II associations in an ethnically varied cohort, molecular class II HLA typing was performed on 200 HCV clearance and 374 matched persistently infected subjects. HLA-DQB1*0301 was weakly associated with viral clearance in combined ethnic groups (odds ratio [OR], 0.72; 95% confidence interval [CI], 0.53-0.97) but was stronger in black subjects. In white subjects, viral clearance was associated with DRB1*0101 (OR, 0.32; 95% CI, 0.17-0.60) and its DQB1*0501 haplotype, whereas viral persistence was associated with DRB1*0301 (OR, 2.36; 95% CI, 1.23-4.52) and its DQB1*0201 haplotype. These results support a role for class II alleles in the immune response to HCV and underscore the importance of studying genetic associations in an ethnically diverse cohort.     

HLA class II distribution in Congolese with hyperthyroidism: preliminary results

OBJECTIVE: Incidence of the hyperthyroidism is continuously increasing, whereas our knowledge concerning the facilitating or etiologic factors of this increase are still partial. To evaluate some of these unknown factors, we started this preliminary study, in order to identify HLA genes in hyperthyroid Congolese, and to determine their susceptibilty in the appearance and development of hyperthyroidism at the Hospital Clinic of Kinshasa. MATERIALS AND METHODS: Nine Congolese women with hyperthyroidism, and thirteen healthy controls (3 women and 10 men) were examined and compared for HLA-DR and HLA-DQ genes analyses, from August 2000 to August 2002. DRB1 and DQB1 alleles were identified, using the Polymerase Chain Reaction (PCR) and immobilized sequence-specific oligonucleotide (SSO HLA-DRB1 and DQB1 test) probes assays. RESULTS: In the group with hyperthyroidism, three alleles (HLA-DR1, HLA-DR2, HLA-DR3) and an allele group (HLA-DR11,13,14) were found for DRB1 locus, while only one allele (HLA-DQB1*0602) was identified for DQB1 locus; allele group HLA-DR11,13,14 was the most frequent (allele frequency=0.50), followed by HLA-DR3 allele (allele frequency=0.222); 6 haplotypes were observed, with predominance of haplotype DR3/DR11,13,14 (genotype frequency=0.333), followed by haplotype DR11,13,14/DR11,13,14-DQB1*0602 (genotype frequency=0.222). In the group of healthy controls, three alleles (HLA-DR2, HLA-DR3, HLA-DR4) and an allele group (HLA-DR11,13,14) were identified for DRB1; HLA-DR2 allele was predominant (allele frequency=0.615), followed by allele group HLA-DR11,13,14 (allele frequency=0.231); a statistic significant difference was observed between the frequencies of DR2 allele and allele group DR11,13,14 in the healthy controls compared to those of hyperthyroid patients (p=0.02); 6 haplotypes were also detected in this group, the most frequent haplotype being HLA-DR2/DR2-DQB1*0602 (genotype frequency=0.540 versus 0.333 in the hyperthyroid group) (p=0.048). HLA-DQB1*0602 was dominant in the healthy controls group (allele frequency=0.890), versus HLA-DQB1*0302 (allele frequency=0.110). CONCLUSIONS: HLA-DR2, HLA-DQB1*0602 and DR2/DR2-DQB1*0.602 would play a protective role against the hyperthyroidism, while DR3 allele, allele group DR11,13,14 and haplotype HLA-DR3/DR11,13,14 would predispose to this disease or to Graves' exophtalmopathy. A large and profound study is needed to confirm our preliminary results.     

Risk variation in celiac disease in a population from Southern Spain: evaluating the influence of the DQB1*02:02 allele frequency

Objectives: To date, the greatest genetic risk factor known for celiac disease (CD) is the presence of HLA-DQ2 heterodimers, specifically DQ2.5 in state of homozygosis or heterozygosis. DQ2.2 variants are the second most important risk factor when carried trans to DQ2. This study aimed to determine the prevalence and risk genotypes of HLA-DR-DQ.

Material and methods: A total of 196 patients with CD and 206 healthy controls from the Province of Málaga (southern Spain) were included. The corresponding risk gradient in our population was established in accordance with the odds ratios (ORs) found.

Results: The heterozygous genotype for DR7-DQ2.2/DR3-DQ2.5 presented the highest risk (OR =6.404, p?=?.0001) followed by the DR3-DQ2.5 homozygous genotype (OR =4.721, p?=?.001). An intermediate risk was found for the DQ2.5 heterozygous genotype with no other DQ risk variant (DQ8 or DQ2.2). Similarly, these three genotypes had also an increase in the risk of associated-autoimmune diseases. The DQB1*02:01 allele was the most widely represented among patients with CD respect to the control group (f?=?0.479, p?=?.0001), with the second most common being DQB1*02:02 (f?=?0.209, p?=?.0001).

Conclusions: In addition to the gene dosage effect confirmed in our report, and in contrast with previous studies, we found a raised risk for those patients with DQ2.2 heterodimers in trans configuration to DQ2.5 compared to DQ2.5 homozygous individuals. Therefore, in our population of patients with CD the frequency of DQ2.2 acts as a factor that increases the genetic risk of developing CD.     

Genetics of the HLA Region in the Prediction of Type 1 Diabetes

Type 1 diabetes (T1D) is one of the most widely studied complex genetic disorders, and the genes in HLA are reported to account for approximately 40–50% of the familial aggregation of T1D. The major genetic determinants of this disease are polymorphisms of class II HLA genes encoding DQ and DR. The DR-DQ haplotypes conferring the highest risk are DRB1*03:01-DQA1*05:01-DQB1*02:01 (abbreviated “DR3”) and DRB1*04:01/02/04/05/08-DQA1*03:01-DQB1*03:02/04 (or DQB1*02; abbreviated “DR4”). The risk is much higher for the heterozygote formed by these two haplotypes (OR = 16.59; 95% CI, 13.7–20.1) than for either of the homozygotes (DR3/DR3, OR = 6.32; 95% CI, 5.12–7.80; DR4/DR4, OR = 5.68; 95% CI, 3.91). In addition, some haplotypes confer strong protection from disease, such as DRB1*15:01-DQA1*01:02-DQB1*06:02 (abbreviated “DR2”; OR = 0.03; 95% CI, 0.01–0.07). After adjusting for the genetic correlation with DR and DQ, significant associations can be seen for HLA class II DPB1 alleles, in particular, DPB1*04:02, DPB1*03:01, and DPB1*02:02. Outside of the class II region, the strongest susceptibility is conferred by class I allele B*39:06 (OR =10.31; 95% CI, 4.21–25.1) and other HLA-B alleles. In addition, several loci in the class III region are reported to be associated with T1D, as are some loci telomeric to class I. Not surprisingly, current approaches for the prediction of T1D in screening studies take advantage of genotyping HLA-DR and HLA-DQ loci, which is then combined with family history and screening for autoantibodies directed against islet-cell antigens. Inclusion of additional moderate HLA risk haplotypes may help identify the majority of children with T1D before the onset of the disease.