Lack of association between the promoter polymorphisms at positions -308 and -238 of the tumor necrosis factor alpha gene and psoriasis vulgaris in Japanese patients

BACKGROUND: Psoriasis features an increased level and activity of tumor necrosis factor alpha (TNF-alpha). The TNF-alpha gene has single nucleotide polymorphisms (SNPs) at positions -308 (-308G>A) and -238 (-238G>A) in the promoter region, and the -238G>A SNP has been reported to be associated with psoriasis vulgaris (PV) and psoriatic arthritis in Caucasians. OBJECTIVE: To examine whether these SNPs are associated with susceptibility to PV in Japanese patients, we investigated the genotype and allele frequencies at each SNP in Japanese PV patients and in controls. METHODS: We examined 163 PV patients and 96 healthy individuals. Genotyping was performed using the polymerase chain reaction-restriction fragment length polymorphism method. RESULTS: No significant association between the genotypes or alleles of these SNPs and susceptibility to PV was observed. CONCLUSION: These SNPs themselves are not associated with susceptibility to PV in the Japanese.