Leukopenia• NUDT15 c.415C>T (OR = 21.7; 95% CI = 12.1–38.8; p < 0.0001)• NUDT15 55_56insGAGTCG (OR = 7.1; 95% CI = 3.7–13.7; p < 0.0001)• TPMT*3C c.7196A>G (OR = 0.40; 95% CI = 0.0–6.8; p = 0.999). Here, TPMT is linked to Decreased total leukocyte count.