No primary association of MICA polymorphism with systemic lupus erythematosus

OBJECTIVE: To replicate the described association between MHC class I chain-related A (MICA) gene polymorphism and susceptibility to systemic lupus erythematosus (SLE). METHODS: MICA transmembrane microsatellite polymorphism was genotyped using a polymerase chain reaction (PCR)-based method. Genotyping of HLA-B* and DRB1* was performed using PCR and detection with a reverse sequence-specific oligonucleotide (SSO) probe system. Combined data for these three loci (HLA-B*, DRB1* and MICA) were obtained from a total of 333 patients and 361 healthy controls. RESULTS: Significant association with B*08 [P < 10(-7), odds ratio (OR) 3.17, 95% confidence interval (CI) 2.02-5.00], DRB1*0301 (P < 10(-7), OR 2.07, 95% CI 1.59-2.68) and MICA5.1 (P = 0.01, OR 1.23, 95% CI 1.04-1.46) was observed. The combinations DRB1*0301-MICA5.1-B8 and HLA-DRB1*0301-B*08-positive and MICA5-1-negative were more frequent among SLE patients (11.4 vs 3.3% in healthy controls, P = 3.9 x 10(-5), OR 3.76, 95% CI 1.85-7.73, and 6.9 vs 1.7%, P = 0.0007, OR 4.32, 95% CI 1.68-13.10, respectively). Additionally, individuals who were HLA-DRB1*0301-B*08-negative and MICA5-1-positive were less frequent among patients (22.2 vs 31.3% in healthy controls, P = 0.007, OR 0.63, 95% CI 0.44-0.89) and the magnitude of the OR was similar to that obtained in individuals negative for all the three factors (OR 0.69, 95% CI 050-0.94). Further analysis performed to detect independent association strongly suggested that the association between MICA5.1 and SLE is secondary to the linkage disequilibrium of this allele with B*08. CONCLUSIONS: Our results do not support an independent association of MICA gene polymorphism with susceptibility to SLE.     

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.     

Epistatic interactions between HLA-DRB1 and interleukin 4, but not interferon-gamma, increase susceptibility to giant cell arteritis

OBJECTIVE: To assess the roles of the interleukin 4 (IL-4) and interferon-g (IFN-g) gene polymorphisms in a series of patients with biopsy-proven giant cell arteritis (GCA). METHODS: Eighty-two patients with biopsy-proven GCA and 102 ethnically matched controls from the Lugo region (Northwest Spain) were studied. The following single nucleotide polymorphisms (SNP) were assessed: IL-4 (SNP1: rs2070874, SNP2: rs2227284, SNP3: rs2227282, SNP4: rs2243266, and SNP5: rs2243267) and IFN-g (SNP1: rs1861494, SNP2: rs1861493, and SNP3: rs2069718). RESULTS: Significant differences in allele and genotype frequencies were observed for the IL-4 SNP between HLA-DRB1*04 negative patients and controls. Epistatic interaction between SNP2 (rs2227284) with HLA-DRB1 showed a significant interaction (p = 0.001) and carriage of the SNP2*T allele in the absence of HLA-DRB1*04 resulted in a 4-fold risk of developing GCA (OR 4.2, 95% CI 1.1-15.6). Also, a significant increase in the frequency of the T-T-C-A-C IL-4 haplotype was observed in HLA-DRB1*04 negative GCA patients compared to the controls (p = 0.02; OR 2.0, 95% CI 1.0-3.9). Similar distributions of allele and genotype frequencies were observed for the IFN-g polymorphisms in both GCA patients and controls. CONCLUSION: Our results suggest an association with IL-4 gene polymorphism that is dependent on HLA-DRB1 genotype in GCA susceptible individuals. These data indicate an interaction between HLA-DRB1 and IL-4 that contributes to pronounced disease susceptibility.     

Lack of association between intercellular adhesion molecule-1 gene polymorphisms and giant cell arteritis

OBJECTIVE: Studies have shown an association between HLA-DRB1*04 and giant cell arteritis (GCA). Intercellular adhesion molecule-1 (ICAM-1) gene polymorphisms were reported to contribute susceptibility to GCA in Italian patients where susceptibility to GCA is not associated with HLA-DRB1*04 alleles. ICAM-1 is also highly expressed within inflammatory infiltrates of the blood vessels of GCA patients. To investigate the clinical implications of ICAM-1 polymorphisms in GCA, we examined their potential association and influence in the development of visual ischemic complications in a series of patients with GCA from Northwest Spain where GCA susceptibility is associated with HLA-DRB1*04. METHODS: Fifty-eight biopsy proven GCA and 129 ethnically matched controls were studied. Patients and controls were genotyped for ICAM-1 polymorphism at codons 241 and 469 by PCR-RFLP. RESULTS: The distribution of the alleles and genotypes for each ICAM- polymorphism did not show significant differences between GCA patients and controls. Although visual manifestations were significantly more likely to occur in men than women (OR 5.2, p = 0.018), allele and genotype frequencies of ICAM-1 polymorphisms in patients with GCA were not associated with development of visual complications or anemia. Visual complications in GCA were primarily associated with carriage of an HLA-DRB1*04 allele. No evidence was found for interaction between HLA-DRB1*04 and ICAM-1 polymorphism. CONCLUSION: ICAM-1 polymorphisms are not genetic risk factors for the susceptibility and severity of GCA in Northwest Spain.     

HLA-DRB1 allele distribution in polymyalgia rheumatica and giant cell arteritis: influence on clinical subgroups and prognosis

OBJECTIVE: To evaluate HLA-DRB1 associations in patients with polymyalgia rheumatica (PMR) and giant cell arteritis (GCA) in the Spanish population, especially those alleles that include the disease-linked sequence motif DRYF (positions 28 to 31 of the HVR2). METHODS: We performed a PCR based HLA-DRB1 genotyping in 89 PMR patients, 44 GCA patients, and 99 unrelated healthy controls from the same geographic area. RESULTS: We did not find any significant difference between the whole group of PMR/GCA patients (n = 133) compared with the healthy controls with the exception of a lower frequency of HLA-DRB1*0405 in the patient group (odds ratio [OR], 0.1 [CI0.02 to 1.2]; P =.04). The distribution of DRB1 alleles was very similar between PMR patients and controls. However, DRB1*0401 (OR, 3.1 [1.1 to 8.6]; P =.02) and DRB1*0404 (OR, 3.5 [0.97 to 12.9]; P =.04) were overrepresented in patients with GCA compared with the control group. DRB1*04 (OR, 1.9 [0.96 to 3.8]; P =.06), especially *0401 (OR, 2.8 [1 to 7.7]; P =.04), and DRB1*07 (OR, 2.3 [1.2 to 4.6]; P =.01) were more frequent in GCA than in PMR. Frequency of the DRYF 28-31 motif was similar among GCA (79.5%), PMR (89.9%), and controls (87.9%) and did not confer any significant risk of the development of systemic vasculitis. We also compared the DRB1 allele distribution in patients with classic PMR (n = 58) and those with an erythrocyte sedimentation rate (ESR) <40 mm/hour (n = 31). Patients with classic PMR expressed DRB1*07 less frequently (OR, 0.4 [0.1 to 1]; P =.04) and had a higher frequency of the DRYF 28-31 motif (94.8% vs 80.6%; P =.03) than patients with ESR < 40. Within the GCA group, DRB1 alleles were not predictive for the development of severe ischemic complications. However, the development of relapses in patients with PMR was associated with a higher frequency of DRB1*09 (5.6% vs 0%; P =.04). CONCLUSIONS: Our data suggest that the HLA-DRB1 alleles associated with susceptibility for developing PMR and GCA are different. Whether PMR with low ESR represents a different clinical subset of the disease should be clarified in a larger sample of patients. HLA-DRB1 genes might predict the presence of relapses in PMR, but they do not seem to be indicators of severe disease in GCA patients.     

Association and frequency of HLA-A, B and HLA-DR genes in south Tunisian patients with spondyloarthritis (SpA)

The aim of this study is to investigate the association of HLA-A, B and HLA-DR gene expression and to assess an association of additional HLA antigens besides HLA-B27 in south Tunisian patients with spondyloarthritis (SpA). Eighty-five patients diagnosed with ankylosing spondylitis (AS, n=68) and reactive arthrithis (ReA, n=17) were selected and compared with 100 healthy controls (HC). HLA class I antigens were typed serologically using microlymphocytotoxicity technique. HLA-DRB1* alleles were studied by polymerase chain reaction amplification with sequence-specific primers. The significance of differences between patients and controls was tested by chi-square analysis. We found significantly increased frequencies of HLA-A3 (30.6%; pC=0.04; OR=2.95), HLA-B27 (62.35%; pC=4.10(-17), OR=53.55), and HLA-DRB1*15 (17.2%; pC=0.026; RR=2.58) alleles in SpA patients compared to HC. The most frequent and strongest association was observed for HLA-B27 in AS (pC=6.6 ×10(-16), OR=52.23). When AS and ReA patients were analysed separately, HLA-DRB1*15 and HLA-A3 were increased only in AS (pC=0.01, OR=2.99 and pC=0.03, OR=3.14, respectively). In ReA patients, HLA-DRB1*04 (p=0.033, pC=NS, OR=2.89) was found to be the most common allele. By analysing the HLA-B27-negative subgroup, HLA-A3 and HLA-DRB1*15 expression was found to be dependent on the presence of HLA-B27. HLA-B27 expression was higher in male (45/53; 85%) as compared to female (8/53; 15%) patients (p=0.03). Apart from HLA-B27, HLA-A3 and HLA-DRB1*15 are the MHC class I and II alleles found most frequent in Tunisian patients with AS, whereas HLA-DRB1*04 was found most frequent in ReA patients. HLA-B27 is more frequent in male than in female patients.     

MHC class I chain-related gene B (MICB) is associated with rheumatoid arthritis susceptibility

OBJECTIVES: Several recent studies have shown that the MHC class III region, located telomeric to HLA-DRB1, contains an additional genetic factor that predisposes to rheumatoid arthritis (RA). In this study, we investigate whether inhibitor of kappaB-like (IkappaBL), MICB or MICA located in the MHC class III region are the second susceptibility gene associated with RA. METHODS: A total of 154 healthy controls and 140 RA patients were genotyped for HLA-DRB1, MICA, MICB and the polymorphism -62 of the IkappaBL gene. RESULTS: A significant increase of HLA-DRB1 shared epitope (SE) alleles was detected in RA patients (61.4 vs 43.5%, P(c) = 0.01, OR = 2.1, 95% CI = 1.3-3.3). Among SE alleles, the HLA-DRB1*0401 (13.5 vs 5.1%, P(c) = 0.04, OR = 3.2, 95% CI = 1.3-8.1) and HLA-DRB1*0404 (6.4 vs 1.2%, P = 0.02, P(c) = NS) showed the most significantly association with RA. No increase of risk was associated with HLA-DRB1*01. Remarkably, the allele MICB*004 was also significantly associated with RA susceptibility (40.7 vs 23.3%, P(c) = 0.01, OR = 2.2, 95% CI = 1.3-3.7). MICB*004 was in linkage disequilibrium with HLA-DRB1*0404 (lambda(s) = 0.33) and HLA-DRB1*0405 (lambda(s) = 0.34). However, MICB*004 was also increased in HLA-DRB1 SE negative patients (37 vs 21.5%, P = 0.04). No significant association between IkappaBL and MICA with RA was found. CONCLUSIONS: MICB*004 allele was associated with RA susceptibility. This allele was in linkage disequilibrium with HLA-DRB1*0404 and DRB1*0405. The association of MICB with RA susceptibility and the functional role of MIC genes in the pathogenesis of RA converts MICB into a candidate to be an additional MHC gene associated with RA susceptibility.     

MICA rather than MICB,TNFA, or HLA-DRB1 is associated with susceptibility to psoriatic arthritis

OBJECTIVE: To analyze the genetic contribution of HLA in development of psoriatic arthritis (PsA) and to study whether MICA is primarily associated with PsA or whether its association is secondary to linkage disequilibrium with centromeric genes, such as MICB, TNFA, or HLA-DRB1. METHODS: DNA samples from 81 Spanish patients with PsA and 110 healthy controls were examined by polymerase chain reaction (PCR) sequence-specific primers to type HLA-Cw and HLA-DRB1, PCR sequence-specific oligonucleotides to determine HLA-B, and PCR restriction fragment length polymorphism for tumor necrosis factor-alpha promoter polymorphisms at positions -238 and -308. Analysis of microsatellite polymorphisms in the transmembrane region of MICA and in intron 1 of MICB was also carried out. RESULTS: HLA-Cw*0602 was significantly increased in PsA [60% vs 17%; p(c) < 0.00002, OR 7.33, etiological fraction (EF) 0.52]. MICA-A9 (60% vs 30%; p(c) = 0.0002, OR 3.57, EF 0.43) and the microsatellite MICB-CA-22 allele (23% vs 7%; p(c) = 0.028, OR 3.9, EF 0.17) were also significantly increased in PsA. MICA-A9 was in linkage disequilibrium with MICB-CA-22 (delta = 0.6). The association of MICA-A9 was independent of MICB-CA-22 and Cw*0602, since it was also associated in MICB-CA-22 negative (p(c) = 0.0015, OR 2.96, EF 0.34) and in Cw*0602 negative patients (p(c) = 0.034, OR 2.83, EF 0.34). TNFA and DRB I alleles were not significantly associated with PsA. CONCLUSION: Cw*0602 and MICA-A9 appear to be the strongest genetic susceptibility factors for PsA. However, MICA-A9 was associated independently of Cw6. HLA-B alleles and MICB-CA22 are associated secondarily to linkage with MICA. TNFA and HLA-DRB1 were not associated with PsA susceptibility, and our data suggest that their reported association may only reflect the linkage disequilibrium with MICA-A9 among the different populations studied.     

IL-6 promoter polymorphism at position -174 modulates the phenotypic expression of polymyalgia rheumatica in biopsy-proven giant cell arteritis

OBJECTIVES: Giant cell arteritis (GCA) and polymyalgia rheumatica (PMR) are related diseases in which diverse genetic and environmental factors are implicated. Both GCA and PMR are characterized by an intense acute phase reaction. In these sYndromes the increased production of IL-6 has been observed. To investigate further the genetic influence of IL-6 in GCA and PMR we have examined the IL-6 promoter polymorphism (G to C) at position -174 in the 5' region in a series of patients from Northwest Spain diagnosed with GCA and/or PMR. METHODS: Sixtxy-two biopsy-proven GCA patients (30 of them with associated PMR) and 84 patients with isolated PMR were studied. Patients and ethnically matched controls (n = 124) were from the Lugo region (Galicia, Northwest Spain). Patients and controls were genotyped for HLA-DRB1 and IL-6 polymorphism at position -174 by molecular methods. RESULTS: IL-6-174 allele C was marginally increased infrequency in GCA patients with PMR manifestations compared with isolated GCA (Pcorr 0.06; OR = 2.3). The increase in the frequency of the CC genotype in GCA patients with PMR versus those with isolated GCA was statistically significant (Pcorr 0.02). The increased frequency of allele C in GCA patients with PMR was more commonly observed in HLA-DRBI *04 negative patients. However, this polymorphism was not associated with a higher risk of ischemic events in GCA or with relapses in PMR. CONCLUSION: Allele C at position -174 in the 5' promoter region of the IL-6 gene may be associated with PMR in biopsy-proven GCA patients not carrying HLA-DRBI *04 alleles.     

HLA-DRB4 as a genetic risk factor for Churg-Strauss syndrome

OBJECTIVE: To explore the association between HLA alleles and Churg-Strauss syndrome (CSS), and to investigate the potential influence of HLA alleles on the clinical spectrum of the disease. METHODS: Low-resolution genotyping of HLA-A, HLA-B, and HLA-DR loci and genotyping of TNFA -238A/G and TNFA -308A/G single-nucleotide polymorphisms were performed in 48 consecutive CSS patients and 350 healthy controls. RESULTS: The frequency of the HLA-DRB1*07 allele was higher in the CSS patients than in controls (27.1% versus 13.3%; chi(2) = 12.64, P = 0.0003, corrected P [P(corr)] = 0.0042, odds ratio [OR] 2.42, 95% confidence interval [95% CI] 1.47-3.99). The HLA-DRB4 gene, present in subjects carrying either HLA-DRB1*04, HLA-DRB1*07, or HLA-DRB1*09 alleles, was also far more frequent in patients than in controls (38.5% versus 20.1%; chi(2) = 16.46, P = 0.000058, P(corr) = 0.000232, OR 2.49, 95% CI 1.58-3.09). Conversely, the frequency of the HLA-DRB3 gene was lower in patients than in controls (35.4% versus 50.4%; chi(2) = 7.62, P = 0.0057, P(corr) = 0.0228, OR 0.54, 95% CI 0.35-0.84). CSS has 2 major clinical subsets, antineutrophil cytoplasmic antibody (ANCA)-positive, with features of small-vessel vasculitis, and ANCA-negative, in which organ damage is mainly mediated by tissue eosinophilic infiltration; analysis of HLA-DRB4 in patients categorized by different numbers of vasculitic manifestations (purpura, alveolar hemorrhage, mononeuritis multiplex, rapidly progressive glomerulonephritis, and constitutional symptoms) showed that its frequency strongly correlated with the number of vasculitis symptoms (P for trend = 0.001). CONCLUSION: These findings indicate that HLA-DRB4 is a genetic risk factor for the development of CSS and increases the likelihood of development of vasculitic manifestations of the disease.     

Association between the HLA-DRB1 gene and clinical features of systemic sclerosis in Korea

OBJECTIVE: To determine whether HLA-DR alleles are associated with the development and clinical features of systemic sclerosis (SSc) in Koreans. METHODS: Seventy-nine patients (74 women and five men; 45 diffuse types and 34 limited types; mean age at diagnosis 43.9 years) fulfilling the American College of Rheumatology (ACR) classification criteria for SSc were enrolled. The controls were 144 healthy, disease-free Koreans. HLA-DRB1 genotypes were assessed by the polymerase chain reaction-sequence specific oligonucleotide probe (PCR-SSOP) method. RESULTS: The HLA-DRB1*15 allele was increased in anti-topoisomerase I autoantibody (anti-topo I)-positive SSc patients [p = 0.003, p corrected (p(corr)) = 0.039, odds ratio (OR) = 3.43, 95% confidence interval (CI) 1.45-8.13] compared with controls. The DRB1*11 allele was also observed more frequently in anti-topo I-positive SSc than in controls (13.3% vs. 4.2%) but not statistically significant (p = 0.053, p(corr) = 0.689). In patients with SSc, the DRB1*04 allele was associated with subcutaneous calcinosis (p = 0.048, OR = 4.56, 95% CI 1.07-19.37). Patients with overlap syndrome showed a negative association with the DRB1*04 allele (p = 0.036, OR = 0.26, 95% CI 0.08-0.91). CONCLUSION: The HLA-DRB1*15 allele was associated with the development of anti-topo I-positive SSc in Koreans. In addition, the DRB1*04 allele was associated with certain clinical features in SSc patients.     

Mapping of the HLA-linked genes controlling the susceptibility to Takayasu's arteritis

To further define the HLA-linked genes controlling the susceptibility to Takayasu's arteritis, polymorphisms in five microsatellites around the HLA-B and MICA genes, C1-2-A, MIB, C1-4-1, C1-2-5, and C1-3-1, were investigated in 91 Japanese patients with Takayasu's arteritis and 248 healthy Japanese controls. It was found that allele 238 of C1-2-A [60.4% in patients vs. 29.8% in controls, odds ratio (OR)=3.59, P(c)<0.000004], allele 332 of MIB (22.0% vs. 6. 1%, OR=4.32, P(c)<0.0003), allele 208 of C1-2-5 (47.3% vs. 24.6%, OR=2.75, P(c)=0.001), and allele 291 of C1-3-1 (62.6% vs. 44.8%, OR=2.07, P(c)<0.02) were significantly associated with the disease. Combined analyses of polymorphisms in the HLA-B and MICA genes with those in the microsatellites suggest that there are two different disease-susceptible loci for Takayasu's arteritis; one is mapped near the C1-2-A locus and the other is more closely linked to the HLA-B gene than to the MICA gene, because there are at least two different disease-associated HLA-B haplotypes, HLA-B*52 and -B*39.2 haplotypes, in which the disease-associated C1-2-A allele is shared in common.     

HLA-DRB1, DQA1, and DQB1 alleles associated with giant cell arteritis in northern Italy.

OBJECTIVE: To evaluate by molecular typing the possible associations of HLA-DRB1, DQA1, and DQB1 alleles with biopsy proven giant cell arteritis (GCA) in a Mediterranean country, and to examine possible relationships between these alleles and GCA clinical subsets. METHODS: Thirty-nine patients from the Reggio Emilia area diagnosed over a 12 year period with biopsy proven GCA were studied. The clinical findings at diagnosis and during the followup were evaluated through interviews and by reviewing the medical records. HLA-DRB1, DQA1, and DQB1 alleles were determined in the 39 patients and in 250 healthy controls from the same geographic area by polymerase chain reaction amplification using sequence-specific primers. RESULTS: No associations were found between GCA and the shared epitope, the DRYF epitope, or the DRB1*04 or DQA1 alleles. The only significant association was with DQB1*0302 allele (p = 0.03, RR = 2.2). However, the association was weak and the significance was lost when corrected for the number of antigens tested. The frequencies of DQB1*0301 and 0302 in DR4 patients were not significantly different from those observed in DR4 positive controls. Significant associations were found between DRB1*04 allele and the presence of systemic signs and/or symptoms (p = 0.04, RR = 1.5) and between DRB1*07 allele and the male patients (p = 0.04, RR = 2.6). CONCLUSION: Our data showed no associations of biopsy proven GCA with HLA-DRB1*04 and HLA-DRB1*01 alleles, rheumatoid epitope, or DRYF epitope. Discrepancies with other studies may be related to the different ethnic backgrounds of the populations studied and to differences in the referral patterns of patients with GCA.     

Chronic periaortitis and HLA-DRB1*03: another clue to an autoimmune origin

OBJECTIVE: Patients with chronic periaortitis (CP) often show clinical and laboratory findings of a systemic autoimmune disorder. The aim of the present study was to investigate the role of the HLA system in CP. METHODS: Low-resolution genotyping for HLA-A, HLA-B, and HLA-DRB1 loci and genotyping of TNFA(-238)A/G and TNFA(-308)A/G single nucleotide polymorphisms were performed in 35 consecutive patients with CP and 350 healthy controls. RESULTS: The HLA-DRB1*03 allele frequency was strikingly higher in patients with CP than in controls (24.28% versus 9.14%; chi(2) = 15.50, P = 0.000084, corrected P [P(corr)] = 0.0012, odds ratio [OR] 3.187, 95% confidence interval [95% CI] 1.74-5.83); the HLA-B*08 allele frequency was also higher in patients than in controls (17.14% versus 6.28%; chi(2)=11.12, P = 0.0008, P(corr) = 0.0269, OR 3.085, 95% CI 1.54-6.16). The A*01 allele frequency was significantly different (P = 0.0463), but the statistical significance was lost after correction for multiple testing (P(corr) = 0.5088). TNFA(-238)A allele and TNFA(-308)A allele frequencies were not significantly different (P = 0.512 and P = 0.445, respectively). Comparison of the main clinical and laboratory findings suggestive of a systemic autoimmune disease (e.g., acute-phase reactants, constitutional symptoms, other autoimmune diseases associated with CP) between the HLA-DRB1*03-positive and the HLA-DRB1*03-negative patients showed that the former group had significantly higher levels of C-reactive protein (P = 0.045) at disease onset, although this difference was not statistically significant after correction for multiple tests (P(corr) = 0.369). CONCLUSION: The HLA system plays a role in susceptibility to CP. The strong association between CP and HLA-DRB1*03, an allele linked to a wide range of autoimmune conditions, further supports the view that CP may represent a clinical manifestation of an autoimmune disease.     

HLA-B*27/HLA-B*07 in combination with D6S273-134 allele is associated with increased susceptibility to juvenile spondyloarthropathies

OBJECTIVE: Juvenile spondylarthropathies (jSpA) are polygenic and the clustering of disease in families is caused mainly by genetic factors. Our aim was to look for possible associations of other HLA-A and B specificities, MICA and D6S273 microsatellite polymorphisms that might play a role in determining the susceptibility to jSpA. PATIENTS AND METHODS: jSpA were diagnosed in 74 Croatian children, and 169 healthy unrelated individuals served as the control group. HLA class I (A, B) typing of all individuals was performed, and HLA-B7 and HLA-B27 positive subjects were subtyped by PCR-SSP method. MICA and D6S273 microsatellites alleles were analyzed by electrophoresis in an automated sequencer. RESULTS: We identified 26 HLA-B*07 and 31 HLA-B*27 positive patients with jSpA. DNA subtyping of HLA-B*27 specificity demonstrated only two subtypes, B*2702 (19.35%) and B*2705 (80.65%), among jSpA patients. Subtyping analysis of HLA-B*07 gene showed presence of only one subtype, B*0702. The OR for HLA-B*07 was 2.61, while the highest OR for a single HLA specificity was found for HLA-B*27 (OR=5.60). The HLA-B*07/B*27 combination found in six children showed higher risk (OR=14.82), but the combination of specificities: HLA-B*07/HLA-B*27, and D6S273-134 allele demonstrated the highest risk (OR=26.83). The association with D6S273-134 allele was not a result of the linkage disequilibrium with HLA-B*27 specificity (LD=-0.5). CONCLUSION: Our findings provide evidence that HLA-B*27/HLA-B*07 in combination with D6S273-134 allele is associated with increased susceptibility to jSpA in Croatian children.     

Mapping MHC-encoded susceptibility and resistance in primary sclerosing cholangitis: the role of MICA polymorphism

BACKGROUND & AIMS: Recent studies suggest that major histocompatibility complex-encoded susceptibility to primary sclerosing cholangitis (PSC) maps to the HLA B-TNFA region on chromosome 6p21.3. METHODS: The present study uses a standard polymerase chain reaction protocol to investigate the 16 common alleles of the MICA locus as candidates in 2 patient populations (King's College Hospital, London, and John Radcliffe Hospital, Oxford). RESULTS: The MICA*002 allele was found in 4 of 62 (6.4%) patients and none of 50 patients vs. 41 of 118 (35%) controls (pc = 0.00018, odds ratio [OR] = 0.12, and P = 0.0000016, OR = 0.0, respectively). Overall, the MICA*008 allele was more common in PSC (gene frequency 66% vs. 48% of controls, P = 0.0023, OR = 2.11). However, unlike MICA*002 in which the difference was a result of the absence of MICA*002 heterozygotes, the MICA*008 association may be caused by an increased frequency of MICA*008 homozygosity in patients (58% vs. 22%, pc = 0.000015, OR = 5.01 and 58% vs. 22%, P = 0.0000056, OR = 4.51, respectively). Though MICA*008 is found on the ancestral 8.1 haplotype, stratification analysis indicates that this association is independent of B8 and other HLA haplotypes associated with PSC. CONCLUSIONS: The MICA*002 allele has a strong dominant effect in reducing the risk of PSC, whereas the increased risk of disease associated with MICA*008 may be a recessive effect requiring 2 copies of the MICA*008 allele.     

HLA haplotype analysis in Finnish patients with rheumatoid arthritis

OBJECTIVE: To further characterize the HLA gene products that play an important role in the pathogenesis of rheumatoid arthritis (RA). METHODS: One hundred thirty-four haplotypes from 67 Finnish RA patients and 77 control haplotypes were analyzed for HLA-DRB1 loci, associated alleles of the HLA-DQB1 locus, alleles of the type 2 transporter-associated antigen processing (TAP2) genes, and HLA-B27. In addition, a panel of microsatellite markers within the HLA class I and class III regions was studied. RESULTS: The frequency of HLA-DRB1*04 in the haplotypes of RA patients was found to be 34% (45 of 134) compared with 14% (10 of 72) in control haplotypes (P = 0.004). The frequency of HLA-DRB1*13 was decreased in RA haplotypes (4%, or 5 of 134) in contrast to control haplotypes (24%, or 17 of 72) (P = 0.000031). The decrease in DRB1*13 was not secondary to the increase in DRB1*04, since it was also found among DRB1*04-negative haplotypes (P < 0.001). The DRB1*13-associated DQB1*0604 allele was similarly decreased in RA haplotypes (P = 0.025). The TAP2I allele of I/J dimorphism was increased in RA patients (85%, or 114 of 134) as compared with controls (69%, or 49 of 71) (P = 0.011). Of the tumor necrosis factor (TNF) microsatellite alleles, TNFa6 and TNFb5 were found to be increased in RA haplotypes (for a6 27% versus 5% in controls [P = 0.00043], and for b5 43% versus 26% in controls [P = 0.037]). CONCLUSION: Both protection-associated and susceptibility-associated alleles can be found among HLA class II genes, and the results suggest that loci outside DR/DQ may contribute to the pathogenesis of RA.     

应用基因芯片分析HLA-DRB与晚期肝脾型日本血吸虫病的相关性

目的 探讨人类白细胞抗原Ⅱ类(HLA-Ⅱ）基因多态性与晚期肝脾型日本血吸虫病的遗传关联性。 方法 应用基因芯片分析技术对武汉市蔡甸45例晚期肝脾型日本血吸虫病患者（实验组）和44例慢性日本血吸虫病患者（对照组）的HLA-Ⅱ基因DRB位点等位基因进行基因分型，并比较两组各等位基因频率以及与晚期肝脾型日本血吸虫病的相关性。 结果 实验组HLA-DRB1*04x等位基因频率明显高于对照组（P＜0.01， RR=3.928），而对照组HLA-DRB1*15x等位基因频率明显高于实验组（P＜0.01， RR=0.050）。等位基因DRB1*15x总与DRB5*010x/020x连锁，对照组DRB1*15x-DRB5*010x/020x连锁体频率明显高于实验组（P＜0.01）。 结论 HLA-DRB1*04x与晚期肝脾型日本血吸虫病呈正相关，而HLA-DRB1*15x与晚期血吸虫病呈负相关。     

CARD15 and HLA DRB1 alleles influence susceptibility and disease localization in Crohn's disease

OBJECTIVES: Crohn's disease (CD) is a chronic inflammatory disease of the gut associated with allelic variants of CARD15 and HLA-DRB1 genes. We investigated the prevalence and effects of these variants in a Canadian CD cohort. METHODS: 507 unrelated CD patients were genotyped for the three major CD-associated variants (Arg702Trp, Gly908Arg, and Leu1007fsinsC) and for thirteen HLA-DRB1 alleles. RESULTS: At least one CARD15 variant was present in 32.5% of the CD patients compared with 20% of controls. The prevalence of CARD15 mutation was similar in both sporadic and familial and Jewish and non-Jewish CD patients. The Gly908Arg variant was significantly higher and the Arg702Trp variant significantly lower in Jewish compared to non-Jewish patients. A positive association between the HLA-DRB1*0103 allele and CD was detected in non-Jewish, familial cases (p = 0.0002), with risk for CD increased by 6.7 fold by the presence of an HLA-DRB1*0103 allele as compared to 1.9 fold and 19 fold by a single or two CARD15 variant alleles, respectively. We show a significant association of ileal involvement with CARD15 variants (OR = 1.8; p = 0.02), HLA-DRB1*0701 (OR = 1.9; p = 0.006) and DRB1*04 (OR = 1.7; p = 0.02) alleles and demonstrate the capacity of combined CARD15 and HLA-DRB1 genotyping to predict ileal disease in CD patients. By contrast, the HLA-DRB1*0103 allele was associated with later age of diagnosis (p = 0.02) and pure colonic disease (p = 0.000013). CONCLUSIONS: These observations confirm the influence of CARD15 and HLA-DRB1 alleles on both CD susceptibility and site of disease and identify genotyping of these variants as a potential tool for improved diagnosis and risk prediction in CD.