Endoplasmic reticulum aminopeptidase 1 (ERAP1) polymorphisms and psoriasis susceptibility: A systematic review and meta-analysis

Background: Psoriasis has a complex genetic background with a strong heritable component. Herein, the present meta-analysis aims to evaluate the association of ERAP1 polymorphisms with psoriasis susceptibility. Methods: PubMed, Web of Sciences, Scopus, and Cochrane Library databases were examined with no time limits up to March 2019, without language, age, and sex restrictions. The odds ratio (OR) and 95% confidence interval (CI) were calculated by CMA 2.0 software in a dichotomous analysis using computed effect sizes and having OR and confidence limits for each study. The subgroup analysis based on ethnicity, type of study, and genotyping method was performed. Results: Thirteen articles were involved in the meta-analysis, in details eight were cohort studies and five were case-control studies. The results showed an association between rs27524 [OR = 1.179; 95%CI: 1.081, 1.286; p < 0.001] and rs30187 [OR = 1.237; 95%CI: 1.133, 1.351; p < 0.001] polymorphisms and psoriasis susceptibility; whereas no association was detected with rs26653 [OR = 1.013; 95%CI: 0.798, 1.286; p = 0.914] and rs27044 [OR = 1.164; 95%CI: 0.982, 1.381; p = 0.080] polymorphisms. Psoriasis susceptibility in both Caucasian and Asian ethnicities was related to rs27524 polymorphism, while rs30187 and rs27044 polymorphisms were over-represented in patients belonging to Caucasian ethnicity. In addition, in cohort studies, psoriasis susceptibility was related to rs27524 polymorphism, while the associated polymorphisms were rs26653 and rs27044 in case-control studies, and rs30187 in both cohort and case-control studies. Conclusions: These findings showed an association between rs27524 and rs30187 polymorphisms and susceptibility to psoriasis, while lack of association was obtained for rs26653 and rs27044 polymorphisms. In order to confirm our results, further studies are needed, also considering different factors, such as type of psoriasis and ethnicity.