Genotyping of thiopurine methyltransferase in patients with acute leukemia using LightCycler PCR

Patients with acute lymphoblastic leukemia (ALL) are treated with thiopurines. Thiopurine methyltransferase (TPMT) catalyses the S-methylation of thiopurines and is subject to genetic polymorphism. The TPMT genotype was determined in 55 patients with ALL. Three patients were heterozygous for allelic variants of TPMT. We describe an assay for the genotyping of the TPMT polymorphism using real-time fluorescence polymerase chain reaction (PCR) to facilitate rapid processing of samples. This strategy is superior to standard PCR-restriction fragment length polymorphism genotyping methods and provides informative data on TPMT polymorphisms in patients prior to treatment with thiopurines.