The purpose of this study was to investigate the relative risk of the thiopurine methyltransferase (TPMT) and inosine triphosphate pyrophosphatase (ITPA) genotypes and TPMT activity for the development of leukopenia in Korean IBD patients during AZA/6-MP treatment.
Polymorphisms in TPMT might be associated with myelotoxicity and leukopenia in AZA treated patients, while ITPA variant alleles appear not to be linked with treatment-related side effects.
Seven out of 19 patients (36.8%) with the ITPA 94C>A mutation developed leukopenia; however, this mutation may not unequivocally increase the risk of developing leukopenia.