The rs4680 single nucleotide polymorphism (SNP) in COMT, which causes a three- to fourfold decrease in the dopamine metabolizing activity of this enzyme (Lachman et al., 1996), increases the risk of psoriasis (Sobolev et al., 2019), although variable changes in COMT levels in response to different treatments suggest increases in systemic or local dopaminergic tone are only a part of the disease process (Souteiro et al., 2013). This evidence concerns the gene COMT and psoriasis.