Genotyping of 105 Caucasian children with ALL revealed that 82% of the patient are low CYP3A5 expressers (CYP3A5*3 genotype) with a higher incidence and severity of vincristine-induced side effects and more reductions of vincristine compared with CYP3A5 expressers [59]. Here, CYP3A5 is linked to acute lymphoblastic leukemia.