Clinical Features of Japanese Patients with Behçet's Disease and MICA Polymorphism

Associations between major histocompatibility complex class I chain-related gene A polymorphisms and susceptibility to Behcet's disease. A meta-analysis

OBJECTIVE

The purpose of this work was to investigate whether major histocompatibility complex class I chain-related gene A (MICA) polymorphisms are associated with susceptibility to Behcet's disease (BD).

METHODS

A meta-analysis was conducted on the associations between the MICA-transmembrane (TM) A6 allele and the 009 allele of MICA exon 2-4 (MICA*009) and BD with or without HLA-B51 overall and in each ethnic group.

RESULTS

Fifteen comparison studies were included in this meta-analysis. The meta-analysis revealed a significant association between the MICA-TM A6 allele and BD in European, Asian, and Arab populations [odds ratio (OR) 1.436, 95 % confidence interval (CI) 1.111-1.857, p = 0.006; OR 1.999, 95 % CI 1.551-2.575, p = 8.0 × 10(-8); OR 1.333, 95 % CI 1.058-2.300, p = 0.025, respectively,]). Stratification by HLA-B51 showed an association between the MICA-TM A6 allele and BD with HLA-B51 in the overall group and in the European population. Meta-analysis showed a significant association between the MICA*009 allele and BD in the overall group (OR 3.948, 95 % CI 2.680-5.815, p < 1.0 × 10(-8)) and in the European population (OR 3.392, 95 % CI 2.118-5.433, p = 5.6 × 10(-6)). A significant association was found between the MICA*009 allele and B51-positive BD.

CONCLUSION

This meta-analysis shows that the MICA-TM A6 allele and the MICA*009 allele are associated with BD susceptibility in various ethnic populations, and that MICA alleles are in strong linkage disequilibrium with HLA-B51 in BD.

Linkage disequilibria between human leucocyte antigen-B and closely linked microsatellites in the Croatian population

The aim of the present study was to investigate polymorphism of D6S2927, STR_MICA, D6S2793, TNFa (D6S2792), TNFb and TNFd (D6S2789) microsatellites and linkage disequilibria between these loci and human leucocyte antigen (HLA)-B (previously tested) for better characterisation of extended HLA haplotypes. A total of 176 healthy unrelated Croatians were studied using polymerase chain reaction amplification and electrophoresis on 6% polyacrylamide gel in ALFexpress sequencer. Eight HLA-B/D6S2927 haplotypic associations (B*07/D6S2927-4, B*08/D6S2927-3, B*18/D6S2927-3, B*27/D6S2927-1, B*35/D6S2927-5, B*38/D6S2927-4, B*51/D6S2927-2 and B*61/D6S2927-1) showed strong association (P < 0.001, D > 0.5). Among 88 different HLA-B/STR_MICA haplotypic associations, seven combinations (B*07/STR_MICA-A5.1, B*08/STR_MICA-A5.1, B*15/STR_MICA-A5, B*18/STR_MICA-A4, B*27/STR_MICA-A4, B*38/STR_MICA-A9 and B*51/STR_MICA-A6) demonstrated high linkage (D> or = 0.3) with significant P value (P < 0.001). Strong associations were also observed for five HLA-B/D6S2793 haplotypes (B*07/D6S2793-CA17, B*08/D6S2793-CA24, B*13/D6S2793-CA18, B*14/D6S2793-CA14 and B*27/D6S2793-CA14). HLA-B*08/TNFb3 and HLA-B*50/TNFb7 were the strongest associations for HLA-B/TNFb. Nine HLA-B/TNFa combinations were observed with significant P value (B*07/TNFa11, B*08/TNFa2, B*13/TNFa7, B*18/TNFa10, B*27/TNFa6, B*37/TNFa9, B*38/TNFa10, B*39/TNFa13 and B*44/TNFa4). Out of six HLA-B/TNFd haplotypic associations with strong D value, HLA-B*08/TNFd2 and B*37/TNFd3 showed the highest statistical significance (P < 0.0001). These results provide data on the region around the HLA-B that is very attractive because of its contribution to genetic susceptibility for many HLA-associated diseases and therefore this information will help in all further HLA-B locus-associated disease studies.