The present study aimed to investigate the association between the genetic polymorphism of
cytochrome P450 family 3 subfamily A member 5 (
CYP3A5) and the activity of
CYP3A and plasma concentrations of daunorubicin (DNR) in patients with acute
leukemia. A total of 36 children with newly diagnosed
acute lymphoblastic leukemia were enrolled in the study. Polymerase chain reaction (PCR)‑restriction fragment length polymorphism and PCR product sequencing were used to detect the genotype of
CYP3A5*3. PCR was then used to express the
mRNA expression of
CYP3A5. A
midazolam probe method was used to detect
CYP3A enzyme activity, and DNR concentrations were measured using high performance liquid chromatography. Children with different genotypes had different
mRNA expression levels of
CYP3A5, and
CYP3A enzyme activity in children with the
CYP3A5*1 allele was higher, compared with that in children with the
CYP3A5*3 allele. In addition, the area under the curve (AUC)0‑24 h and AUC0‑∞ of DNR were significantly different in children with different genotypes, however, no statistically significant differences were found in half‑life or maximum concentration. The AUC of DNR was increased in children with acute lymphatic
leukemia who suffered from
cardiotoxicity, compared with those in the normal group. The
CYP3A5*3 gene polymorphism was closely associated with the
mRNA expression of
CYP3A5,
CYP3A enzyme activity and DNR plasma drug concentration, and exhibited different drug adverse reactions.