More recently performed genome-wide association (GWAS) studies on psoriasis vulgaris have identified several additional psoriasis risk factors that comprise genes associated with chronic inflammation including IL12B (9, 10), IL23A and IL23R (9), IL2/IL21 (7), TNFAIP3 and TNIP1 (9), ZNF313 (11), and epidermal/antimicrobial genes such as SLC12A8 and HBD (human β-defensin gene) (12) and the LCE (late cornified envelope) gene cluster (10). Here, IL23A is linked to psoriasis.