308G/A and 238G/A polymorphisms in the TNF-α gene may not contribute to the risk of arthritis among Turkish psoriatic patients

Abstract

Tumor necrosis factor-alpha (TNF-α) is an important proinflammatory cytokine playing a key role in the pathogenesis of psoriasis (Ps) and psoriatic arthritis (PsA). TNFα gene promoter region single nucleotide polymorphisms (SNPs) affect the clinical course, severity and the response to the treatment. To find out whether TNF-α-238G/A and -308G/A promoter polymorphism in Ps patients increases arthritis risk. The study included 129 psoriatic patients (71 with psoriasis only and 58 with PsA). Two single nucleotide polymorphisms in the TNFα gene promoter region (238G/A and -308G/A) were genotyped by real-time polymerase chain reaction. Ps patients without arthritis had a mean age of 44.20 ± 13.85 years (range 18–68 years), while PsA patients had a mean age of 49.15 ± 13.47 years (range 18–82 years) and presented by dactylitis (67.2%), enthesitis (62.1%) followed by spondylitis (60.3%). Periosteal reaction was present in 19%. The psoriatic arthritis severity index (PASI) was comparable between those with (8.2 ± 7.1) and without (7.3 ± 5.12.1) arthritis. The allele positivity of TNF-238A and -308A was not associated with the risk of arthritis among psoriatic patients (OR: 1.002; 95%CI: 0.38–2.6, p = 0.99 and OR: 1.27; 95%CI: 0.51–3.2, p = 0.6, respectively). In addition, none of the genotypes of the studied TNF-α polymorphisms were significantly associated with arthritis. Only spondylitis was significantly associated more frequently with the GG (67.3%) than the GA (22.2%) TNF-α-308G/A genotype (p = 0.02). None of the haplotypes nor alleles of TNF-α-238G/A and -308G/A polymorphisms were significantly associated with arthritis development among psoriatic patients.