There was no significant difference in AUCs between genotypes of NUDT15 codon 139 and NDUT15 diplotypes (a combined analysis of the haplotypes carrying additional variants) for predicting severe adverse events such as acute severe leukopenia and severe alopecia (AUC for acute severe leukopenia: 0.916 with NUDT15 codon 139 and 0.921 with NDUT15 diplotypes; AUC for severe alopecia: 0.990 with NUDT15 codon 139 and 0.991 with NDUT15 diplotypes). Here, NUDT15 is linked to Decreased total leukocyte count.