Association between ERAP1 gene polymorphisms and ankylosing spondylitis susceptibility in Han population

Purposes: The present study was designed to investigate the relationship between endoplasmic reticulum amino peptidase 1 (ERAP1) gene polymorphisms and ankylosing spondylitis (AS) in Han population of Shaanxi province. Methods: 100 AS patients and 100 healthy people were enrolled in present study as case and control groups respectively, and the control group was matched with the case group by age and gender. ERAP1 gene rs27434 and rs7711564 polymorphisms were test by TaqMan probe genotyping method. SHEsis software was used to operate linkage disequilibrium (LD) and haplotype analysis between the two single nucleotide polymorphisms (SNPs). chi(2) test was employed to compare the differences of the genotype, allele and haplotype frequencies between the case and control groups. Relative risk of AS was represented by odds ratios (ORs) and 95% confidence intervals (95% CIs). Results: In ERAP1 rs27434 and rs7711564 polymorphisms, the frequencies of AA and CC genotypes in case group were significantly higher compared to those in control group (P=0.036; P=0.039), and so were the frequencies of A and C alleles (OR=1.589, 95% CI=1.070-2.359, P=0.028; OR=1.535, 95% CI=1.021-2.308, P=0.050). Linkage disequilibrium test and haplotype analysis of the alleles of the two SNPs showed that the frequency of A-C haplotype was higher in case group than that in control group (P=0.005), which indicated that A-C might be the susceptible haplotype to AS. Conclusions: ERAP1 gene rs27434 and rs7711564 polymorphisms may increase the risk of AS.