The discovery of gene associations enabled the development of safe and effective drugs that directly target genes responsible for psoriasis, such as biologics antagonizing tumor necrosis factor (TNF), the p40 subunit of both interleukin (IL)12 and IL23, and the p19 subunit of IL-23 (IL23p19) and IL17 (Table 2) [5]. Here, IL17A is linked to psoriasis.