Association study of ankylosing spondylitis and polymorphisms in ERAP1 gene in Zhejiang Han Chinese population

The susceptibility loci of ERAP1 polymorphisms have been found to be strongly associated with ankylosing spondylitis (AS). The researches in multiple ethnic cohorts suggested that the population attributable risk in ERAP1 polymorphisms is at a high significance level. This study was undertaken to estimate the prevalence and incidence of subsets of AS and investigate the specific variants of ERAP1 polymorphisms in AS susceptibility, in the Han ethnic Chinese population in Zhejiang Province. AS patients were selected, diagnosed, and confirmed by a qualified rheumatologist. The basal clinical and demographic characteristics were compared with all subjects. Genotypes for eight selected single nucleotide polymorphisms (SNPs) in ERAP1 gene (rs27038, rs27037, rs27434, rs27980, rs7711564, rs30187, rs10050860, and rs17482078) were determined by using the Sequenom MassARRAY iPLEX platform in Zhejiang Han Chinese population. Association analyses were performed on the whole genotyped data set in 707 unrelated ankylosing spondylitis cases and 837 ethnically matched controls. We observed the strongest association between AS and HLA-B27, which confers over 90 % of ankylosing spondylitis cases. Moreover, we found three loci of ERAP1 polymorphisms were at a high significance level (rs27037 P = 0.00451; rs27434 P = 0.00012; rs27980 P = 0.00682) with AS in Zhejiang population. We also confirmed polymorphism locus of ERAP1 previously reported association with AS (rs27434; P = 5.3 x 10(-12)). Our results indicated a difference in the mechanism of susceptibility loci in subsets of Zhejiang Han Chinese population and provided further evidence that rs27434 is the key polymorphism associated with AS in ERAP1 gene.