Chang et al. reported the efficacy of adjusting the AZA dose based on the results of preemptive genotyping for common variants of NUDT15 (rs116855232; p.R139C), FTO (rs79206939), and TPMT (rs1800460, rs1800462 and rs1142345; p.A154T, p.A80P, p.Y240C or Y240S, respectively) compared with non-genotyping group in 164 Korean IBD patients [35]. Here, NUDT15 is linked to inflammatory bowel disease.