Article Text

PDF
Do ITPA and TPMT genotypes predict the development of side effects to AZA?
  1. J A Duley1,
  2. A M Marinaki2,
  3. M Arenas2,
  4. T H J Florin3
  1. 1Department of Chemical Pathology, Mater Misericordiae Hospital and School of Microbial and Molecular Medicine, University of Queensland, Brisbane, Australia
  1. Correspondence to:
    Dr J Duley
    Chemical Pathology, Mater Health Services, Raymond Terrace, Brisbane 4211, Australia; john.duley{at}mater.org.au

Statistics from Altmetric.com

In a retrospective study of patients with inflammatory bowel disease, van Dieren et al recently reported the absence of a correlation between genotypes for both inosine triphosphate pyrophosphatase (ITPA) and thiopurine methyltransferase (TPMT), with any side effects to azathioprine (AZA) (Gut 2005;54:1664). This contrasts with two other studies. A rigorous prospective study, published recently, has demonstrated a significant association between ITPA genotype and early dropout from AZA therapy.1 Our original publication implicated ITPA in a number of adverse effects, which were independent of myelosuppression.2 Another letter has reported non-association of ITPA with myelosuppression3 but thiopurine induced myelosuppression has been well documented over the past 25 years as associated with TPMT, not ITPA, status.4

However, we draw attention to a peculiar feature of the TPMT results of van Dieren et al that one patient—who suffered severe myelosuppression—was reported as TPMT*3B/*3B genotype. We previously published a meta-analysis of the incidence of the TPMT*3B (G460A) mutation,5 discovering that it is rare, and this has been confirmed by a recent large study, making the chance of homozygosity negligible.6 Indeed, our evidence suggested that even the few …

View Full Text

Request permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.

Linked Articles