The NUDT15 variant was associated with leukopenia (P = 8.26 × 10–7; OR = 7.5; 95% CI 3.08–18.3) and neutropenia (P = 3.54 × 10–6; OR = 8.05; 95% CI 2.96–21.9); however, no significant association with myelosuppression was observed for TPMT*3C and ITPA variants (P > 0.05). This evidence concerns the gene ITPA and neutropenia.