Many of these exemplify the concordance between a drug’s efficacy and the presence of disease susceptibility variants that disrupt the targeted pathway17, including biologics targeting IL-23 (encoded by IL23A and IL12B at the 12q13.3 and 5q33.3 psoriasis susceptibility loci, respectively) and deucravacitinib46 a small-molecule TYK2 inhibitor whose development was directly informed by the presence of loss-of-function alleles of TYK2 that confer protection to psoriasis8. The gene discussed is IL23A; the disease is psoriasis.