Kakuta Y, et al. - Researchers performed association studies of NUDT15 variants and haplotypes with adverse events (AEs), genome-wide association study (GWAS) to discover additional variants, and receiver operating characteristic (ROC) analysis to select the model to predict severe AEs to clarify the best pharmacogenetic test to be used clinically. For the purpose of this investigation, 2630 inflammatory bowel disease (IBD) subjects were recruited and genotyped for NUDT15 p.Arg139Cys. In Japanese patients with IBD, genotyping of NUDT15 codon 139 was sufficient to predict acute severe leukopenia and alopecia.