Association of susceptibility to multiple sclerosis in Southern Han Chinese with HLA-DRB1,-DPB1 alleles and DRB1-DPB1 haplotypes: distinct from other populations

Association of HLA class II with multiple sclerosis (MS) has been widely studied in both Western and Oriental populations. However, such an association is not well documented in Chinese. The objective of this study was to examine the association between the susceptibility to conventional MS in Southern Chinese with HLA-DRB1,-DPB1 alleles and putative DRB1-DPB1 haplotypes. Genotyping of HLA-DRB1 and -DPB1 alleles was performed in 60 patients with conventional MS and 95 controls. Allele frequencies were compared between patients and controls to identify MS-associated alleles. Relative predisposing effect method was used to compare haplotype frequencies in patients and controls and to identify possible predisposing DRB1-DPB1 haplotypes, which were further examined for differences in haplotype carriage rates between the two groups. We found that the allele frequency of DRB1*1501 was not different between patients (18.3%) and controls (21.1%) (p = 0.837). In contrast, frequency of the DPB1*0501 allele was significantly higher in patients (90%) than in controls (67.4%) (odds ratio = 4.36, p = 0.0013, pcorr = 0.025). DRB1-DPB1 linkage disequilibrium was confirmed in both controls and patients. The frequency of the DRB1*1602-DPB1*0501 haplotype in patients (8.33%) was significantly higher than in controls (0%) (p < 0.0001) and the carriage rate of this haplotype was significantly increased in patients (15%) as compared with controls (0%) (p = 0.00013, pcorr = 0.003). Combined, these results suggest that HLA-DRB1*1501 is not associated with susceptibility to conventional MS in Southern Chinese. Instead, both the DPB1*0501 allele and the DRB1*1602-DPB1*0501 haplotype are strong predisposing factors for conventional MS in this population. Our results establish that the HLA profiles of MS in Southern Chinese are distinct from other populations.