HLA-DPB1 and DPB2 Are Genetic Loci for Systemic Sclerosis A Genome-Wide Association Study in Koreans With Replication in North Americans

Objective. To identify systemic sclerosis (SSc) susceptibility loci via a genome-wide association study. Methods. A genome-wide association study was performed in 137 patients with SSc and 564 controls from Korea using the Affymetrix Human SNP Array 5.0. After fine-mapping studies, the results were replicated in 1,107 SSc patients and 2,747 controls from a US Caucasian population. Results. The single-nucleotide polymorphisms (SNPs) (rs3128930, rs7763822, rs7764491, rs3117230, and rs3128965) of HLA-DPB1. and DPB2 on chromosome 6 formed a distinctive peak with log P values for association with SSc susceptibility (P = 8.16 X 10(-13)). Subtyping analysis of HLA-DPB1 showed that DPB1*1301 (P = 7.61 x 10(-8)) and DPB1*0901. (P = 2.55 x 10(-5)) were the subtypes most susceptible to SSc in Korean subjects. In US Caucasians, 2 pairs of SNPs, rs7763822/rs7764491 and rs3117230/rs3128965, showed strong association with SSc patients who had either circulating anti-DNA topoisomerase I (P = 7.58 x 10(-17)/4.84 x 10(-16)) or anticentromere autoantibodies (P = 1.12 x 10(-3)/3.2 x 10(-5)), respectively. Conclusion. The results of our genome-wide association study in Korean subjects indicate that the region of HLA-DPB1 and DPB2 contains the loci most susceptible to SSc in a Korean population. The confirmatory studies in US Caucasians indicate that specific SNPs of HLA-DPB1 and/or DPB2 are strongly associated with US Caucasian patients with SSc who are positive for anti-DNA topoisomerase I or anticentromere autoantibodies.