The efficacy and safety of ritlecitinib, a dual inhibitor of Janus kinase 3 (JAK3) and tyrosine kinase expressed in hepatocellular carcinoma (TEC) family kinases, have been demonstrated in the ALLEGRO phase 2b/3 trial that enrolled patients aged ≥ 12 years with alopecia areata (AA) and ≥ 50% scalp hair loss. The gene discussed is JAK3; the disease is alopecia areata.