Genetic association analysis and frequency of NUDT15*3 with thiopurine-induced myelosuppression in patients with inflammatory bowel disease in a large Dutch cohort.

Thiopurine drugs are cornerstone treatment for patients with inflammatory bowel disease (IBD). The most common adverse drug reaction is thiopurine-induced myelosuppression (TIM), that may partly be explained by the genetic polymorphism NUDT15*3. The aim of this retrospective study was to determine the NUDT15*3 polymorphism frequency and its association with TIM in an IBD patient population in the Netherlands. DNA from patients previously genotyped for TPMT was genotyped for NUDT15*3. In IBD patients treated with thiopurines association tests with TIM were conducted. Out of 988 included patients, 13 (1.3%) were heterozygous for NUDT15*3. Of all patients, 606 had IBD and received thiopurine treatment. In these patients, 8/606 (1.3%) were heterozygous polymorphic for NUDT15*3 of which 50.0% developed TIM compared to 2.3% in the wild type patients (p < 0.001). The study results show a clinically relevant prevalence of NUDT15*3 in the Dutch patient population. Its strong association with TIM suggests pre-therapeutic genotyping potentially clinically utile.