More recently, genome-wide association studies (GWAS) demonstrated that a missense variant (rs116855232, c.415C > T) in the nucleoside diphosphate-linked moiety X motif 15 (NUDT15) gene is strongly associated with thiopurine-related hematopoietic toxicity in patients with IBD [24] and in children with ALL [14]. The gene discussed is NUDT15; the disease is acute lymphoblastic leukemia.