Compared to the GG genotype, we found a higher ALL risk in subjects who harbored variant (AA) genotype (OR=20.9; 95% CI: 6.01-73.1, P<0.0001) and AG genotype (OR=42.6; 95% CI: 8.3-217.5, P<0.0001) of CYP2D6*4 polymorphism. The gene discussed is CYP2D6; the disease is acute lymphoblastic leukemia.