• TPMT*3C was associated with leukopenia grade III/IV (OR = 17.6; 95% CI = 5.8–53.6; p < 0.0001), and thrombocytopenia (OR = 13.4; 95% CI: 4.6–39.2; p < 0.0001)• TPMT*3B (rs1800460) and TPMT*2 were not associated with AZA’s adverse effects. This evidence concerns the gene TPMT and Decreased total leukocyte count.