IL-17 gene polymorphisms in psoriasis

Psoriasis is a complex chronic inflammatory disease, developing by immune-mediated mechanisms with an average of 2% incidence. Although the primary cause of the etiology has not been fully disclosed its thought to be multifactorial and multigenic. In this study, in psoriasis patients, our aim was to determine the frequency of IL-17F (Glu126Gly, His161Arg) and IL-17A (G197A) gene polymorphisms and its effects on psoriasis development risk, age of onset, nail involvement, type of psoriasis and psoriatic arthritis. The study includes 100 psoriasis dermatologic clinic outpatients and 100 healthy volunteers who have no diagnosis either psoriasis or autoimmune diseases at themselves and their family. PCR (Polymerase chain reaction) method was used to determine IL-17F (Glu126Gly, His161Arg) and IL-17A (G197A) gene polymorphisms in the patient and control groups than the results of study groups were compared. There was no significant difference between in terms of IL-17F (Glu126Gly) and IL-17 (G197A) gene polymorphisms between psoriasis patients and healthy controls. IL-17F his161arg CT genotype was found to be significantly higher in the control group compared to patients with psoriasis. (P=0,003). In addition, psoriasis gene polymorphisms were compared between groups of patients according to the character. Psoriatic arthritis patients compared with psoriasis patients and IL-17 (G197A) GG genotype (p=0,028) were found to be significantly higher. Patients without nail involvement compared to patients with nail involvement and IL-17F (Glu126Gly) AG genotype (p=0,008) were found to be significantly increased. Three allelic frequencies that belong to these polymorphisms was evaluated in the patient and control groups. ACA allele was found to be significantly higer in the control group. In conclusion, IL-17F his161arg CT genotype may be protective in terms of the risk of developing psoriasis. In addition, IL-17A (G197A) GG genotype may be a risk factor for the development of psoriatic arthritis. Key words: Psoriasis, Polymorphism, IL-17A, IL-17F