Single Nucleotide Polymorphisms in the Tumor Necrosis Factor-Alpha Gene Promoter Region Alter the Risk of Psoriasis Vulgaris and Psoriatic

Background: It has been confirmed that tumor necrosis factor-alpha (TNFa), a macrophage-derived pro-inflammatory cytokine, plays an important role in the pathogenesis of psoriasis vulgaris and psoriatic arthritis (PsV&PsA). In contrast, the reported association of TNFa gene promoter region single nucleotide polymorphisms (SNPs) and PsV&PsA has remained controversial. Accordingly, we performed a meta-analysis to provide new evidence that SNPs in the TNFa gene promoter region alter not only the risk of psoriasis vulgaris (PsV) or psoriatic arthritis (PsA) but also of PsV&PsA. Methods: Interrelated literature dated to October 2012 was acquired from the PubMed, ScienceDirect, and SpringerLink databases. The number of the genotypes and/or alleles for the TNFa promoter in the PsV and PsA and control subjects was obtained. Odds ratios (ORs) and 95 % confidence intervals (CIs) were used to calculate the risk of PsV and/or PsA with TNFa promoter SNPs. Results: A total of 26 papers of 2159 for PsV (2129 normal controls) and 2360 for PsA (2997 normal controls) were included in our meta-analysis. The results showed that the variant genotype and allele of TNFa-308A/G was protective in pooled groups of patients with PsV&PsA (OR = 0.682, 0.750; 95 % CI, 0.596-0.779, 0.653-0.861). However, the variant genotypes and alleles of TNFa-238A/G and-857T/C had an increased risk of PsV&PsA (OR = 2.493, 2.228, 1.536, 1.486, 95 % CI, 1.777-3.498, 1.628-3.049, 1.336-1.767, 1.309-1.685). Moreover, the meta-analysis revealed a significant association between TNFa-238A/