NUDT15 and Decreased total leukocyte count: In a survey on NUDT15 Arg139Cys polymorphisms and adverse events in 1291 Japanese patients with inflammatory bowel disease previously treated with thiopurines, leukopenia was reported in 45 of 49 patients and hair loss in 46 of 49 patients with the Cys/Cys genotype, and leukopenia was reported in 94 of 275 patients with the Arg/Cys genotype; alerts have been issued [33].