Associations between ERAP1 polymorphisms and ankylosing spondylitis susceptibility: An updated meta-analysis.

Objective. The relationship between the endoplasmic reticulum aminopeptidase 1 (ERAP1) polymorphisms and ankylosing spondylitis (AS) was inconsistent in the recent literatures, a meta-analysis was therefore performed. Methods. A total of 25 independent studies with 24,271 AS patients and 42,666 controls were included after searching electronic databases for studies published before June 2014. The pooled and individual odds ratios (ORs) with 95% confidence intervals (CIs) were presented to assess the associations between ERAP1 polymorphisms and AS in different ethnicities. Results. This meta-analysis includes 25 studies that investigate 8 single nucleotide polymorphisms (SNPs; rs17482078, rs30187, rs2287987, rs27044, rs26653, rs10050860, rs27037, and rs27434) in ERAP1 gene. Overall, six SNPs were associated with AS; two SNPs (rs27044 and rs26653) were not when all studies were pooled into the meta-analysis (rs27044 G vs. C, OR = 1.058, 95% CI = 0.827-1.354; rs26653 C vs. G, OR = 1.154, 95% CI = 0.937-1.422). In Caucasians, all the 8 SNPs were significantly associated with AS. But 5 SNPs (rs17482078, rs2287987, rs27044, rs26653, and rs10050860) did not show statistical association with the risk of AS in Asians. Conclusion. ERAP1 polymorphisms were associated with AS in Caucasians, but their association with AS in Asians needs further exploration.