Considering that the loss of Prdm16 increases lipid-dependent cell fitness and γδT17 differentiation, skin γδT cells may evolve to secrete IL-17 for protection against bacterial infection by downregulating Prdm16 in lipid-rich skin, and excessive secretion of IL-17 may cause the development of psoriasis. The gene discussed is PRDM16; the disease is psoriasis.