Abstract: Objective To study the methylation status of p16 gene in peripheral blood mononuclear cell (PBMC) of patients with plaque psoriasis, and to study its significance in the pathogenesis of the disease. Methods Thirty-four cases of psoriatic patients and 35 healthy controls were measured for the status of promoter methylation in p16 gene by methylation specific PCR (MSP). A region containing CpG site in p16 gene promoter was amplified by MSP. The severity of psoriasis was evaluated by PASI scores. Results The methylation rates of p16 gene in PBMC were significantly higher (P<0.05) in psoriatic patients than those in the controls, but it was unrelated to the severity and course of the disease. Conclusions Higher rates of hypermethylation of p16 gene are found in PBMC of the patients with plaque psoriasis, suggesting that p16 gene hypermethylation of PBMC may be involved in the pathogenesis of psoriasis.

Key words: Psoriasis, Genes, p16, Methylation