Psoriatic arthritis (PsA) is a chronic inflammatory disorder that belongs to the group of spondyloarthritis (SpA). It was found that single nucleotide polymorphisms (SNPs) of endoplasmic reticulum aminopeptidase (ERAP1 and ERAP2) genes influence the risk of ankylosing spondylitis, the most common form of SpA and the risk of psoriasis. Our purpose was to investigate the possible association of ERAP1 and ERAP2 gene SNPs with psoriatic arthritis susceptibility in Romanian population. Subsequent analyses included patients' subgroups according to HLA-B27 status. Psoriatic arthritis patients (N = 98) and random healthy controls (N = 139) were genotyped for ERAP1/2 genes SNPs rs30187, rs27044, rs2910686, and rs2248374 by TaqMan Allelic Discrimination Assays. An additional control group (N = 108; 100% HLA-B27 positive) was used for subsequent analyses. The results showed the association of rs2248374 SNP of ERAP2 gene with the risk of PsA, especially for HLA-B27 negative disease (p = 0.02; OR 1.59). ERAP2 haplotype GT (rs2248374/rs2910686) was significantly under-represented in PsA patients than in controls (43 vs. 55%; p = 0.02). The analysis of ERAP1 SNPs in HLA-B27 positive controls and PsA subgroup showed strong evidence of association for rs30187 (p = 0.005; OR 2.73) and for CC rs30187/rs27044 haplotype (47% in patients vs. 70.5% in controls; p = 0.006). In conclusion, we found a significant association of ERAP2 with PsA and HLA-B27 negative PsA, while ERAP1 association was restricted only to HLA-B27 positive disease. To our knowledge, this is the first study that investigated ERAP2 polymorphisms in relation to PsA susceptibility.
Keywords: ERAP1; ERAP2; Haplotype; Psoriatic arthritis; Single nucleotide polymorphism.