Association between endoplasmic reticulum aminopeptidase-1 (ERAP-1) and susceptibility to ankylosing spondylitis in Iran.

Ankylosing Spondylitis (AS) is an inflammatory arthritis, which affects mainly spine and sacroiliac joints. According to recent studies, ERAP1 is the second most common candidate gene for  AS susceptibility after HLA-B27. The  aim of this study was to  determine the association of ERAP1 gene polymorphisms with AS in Iranian population. The study group comprised 387 Iranian AS patients and 316 healthy controls from Iran. Using Real Time PCR allelic discrimination method,  we genotyped four SNPs (rs30187, rs469876, rs13167972 and rs27434) of ERAP1. We found  that  rs30187 and rs27434 were significantly associated with AS in Iranian population (P=6×10-5, P=7×10-3,  respectively). The rs30187 T/T genotype was associated with AS compared  with C/C  genotype (P=1.5×10-5).  The  rs27434 G/G genotype was inversely associated with  AS (P=5×10-3).  Two  specific haplotypes  including:  rs30187/ rs469876/ rs13167972/ rs27434 TAAA and CAGG  were associated with increased and decreased risk of AS in Iranian population, respectively. These results indicated that ERAP1 SNPs and haplotypes were associated with AS in Iranian population.