Mutations in the MSMO1 gene, which encodes the sterol-C4-methyl oxidase (SMO), and the NSDHL gene can cause psoriasis-like dermatitis, inflammatory cell infiltration, and the accumulation of meiosis-activating sterol (MAS), an intermediate product of cholesterol metabolism, in the skin of patients (107, 108). Here, SMO is linked to psoriasis.