Moreover, epidemiological studies have provided strong evidence suggesting that obesity and weight gain are risk factors for psoriasis.57 Nakamizo and colleagues found that the accumulation of IL-17A-producing γδT cells in psoriatic lesions of high-fat-diet-induced obese mice leads to the aggravation of psoriatic dermatitis. The gene discussed is IL17A; the disease is obesity due to melanocortin 4 receptor deficiency.