2005•PubMedOpen access
ITPA genotyping is not predictive for the development of side effects in AZA treated inflammatory bowel disease patients.
Jolanda M. van Dieren, Adriana J. van Vuuren, JG Kusters, EES Nieuwenhuis, Ernst Johan Kuipers, C. Janneke van der Woude
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Abstract
We read with interest the letter by Colombel et al on the non-predictive value of ITPA genotyping for the development of myelosuppression after azathioprine (AZA) treatment ( Gut 2005; 54 :565).
The level of thiopurine methyltransferase (TPMT) activity is determined by a common genetic polymorphism.1 It was shown that low TPMT activity is linked to a higher relative risk of development of myelosuppression after AZA treatment.2 Testing for TPMT genotype before the start of AZA treatment is of limited clinical value as myelosuppression resulting from TPMT mutations occurs in less then one third of patients with myelosuppression.3
Polymorphisms in genes encoding inosine triphosphate …