NUDT15 genotyping in Caucasian patients can help to optimise thiopurine treatment in patients with inflammatory bowel disease

Thiopurines [azathioprine (AZA) and 6-mercaptopurine (6- MP)] are frequently used for the treatment of inflammatory bowel disease (IBD). Unfortunately ~10–30% of the patients develop adverse drug reactions (1). Myelosuppression is one of the thiopurine related side-effects observed in ~5% of IBD patients from European descent (2-4). The course of thiopurine-induced myelosuppression is relatively mild but patients with this side-effect are more prone to serious infections. It is known that genetics can explain part of the thiopurine-induced myelosuppression.