HLA-DPB1 rs9277535 polymorphism is associated with rheumatoid arthritis risk in a Chinese Han population

We used a custom-by-design 48-Plex single nucleotide polymorphism scan™ kit to investigate the relationship between susceptibility to rheumatoid arthritis (RA) and HLA-DPB1 rs9277535 polymorphism in 805 RA patients and 1095 healthy controls from the Chinese Han population. Blood plasma levels of HLA-DPB1 were also examined using enzyme-linked immunosorbent assays in 170 RA patients and 170 matched control individuals. Quantitative reverse transcription PCR (qRT-PCR) was used to evaluate relative HLA-DPB1 mRNA levels in these blood samples as well. The results indicated that some HLA-DPB1 rs9277535 polymorphisms decreased RA susceptibility. Stratified analysis indicated that risk of RA decreased specifically in women and those who were at least 55 years old. In addition, the AG and GG+AG genotypes were associated with CRP status, ACPA status, and ESR in RA patients when the AA genotype was used as the reference group. Furthermore, average HLA-DPB1 plasma levels were increased in RA patients, and HLA-DPB1 plasma levels and mRNA expression were lower in those with the GG genotype than in those with the AA genotype. These results indicate that HLA-DPB1 rs9277535 polymorphism is associated with a decreased risk of RA in the Chinese population.