The effects of the combined TPMT and ITPA genotype on the mercaptopurine pharmacokinetics were also shown in a study by de Beaumais et al.[25] Furthermore, a study conducted in Indian ALL patients showed an independent role for both TPMT and ITPA in terms of association with the incidence of hematological toxicity [24]. This evidence concerns the gene ITPA and acute lymphoblastic leukemia.