In Japan, the first biologics for psoriasis were infliximab and adalimumab (anti–tumor necrosis factor α [TNF‐α] antibodies) introduced in 2010, followed by ustekinumab (anti–interleukin 12/IL‐23 subunit 40 [IL‐p40] antibody) in 2011. This evidence concerns the gene IL23A and psoriasis.