A nonsynonymous rs116855232 NUDT15 variant (c.415C>T, p.Arg139Cys) has been reported as a strong risk factor for thiopurine-induced leukopenia and 6-MP intolerance in patients with inflammatory bowel disease and pediatric ALL in several reports [12,13,14,15,16,17]. The gene discussed is NUDT15; the disease is acute lymphoblastic leukemia.