Association of genetic polymorphism of NUDT15, TPMT and ITPA gene in the toxicity and efficacy of azathioprine-based regimen in Egyptian inflammatory bowel disease patients

Background: Inflammatory Bowel disease (IBD) is a chronic progressive condition that prompts generous physical and mental morbidity. Choosing the best kind of management and medication dosage prevents new episodes of high disease activity during therapy because of adverse drug reactions (ADRs). This can lead to cessation or inefficacy of the treatment, or complete non-responsiveness to specific medications. Pharmacogenetics (PGx) is a well-established aspect in IBD. One of the exemplary instances of PGx is thiopurines, which are frequently utilized as IBD therapy. This study aimed to evaluate specific gene polymorphism involved in the toxicity and efficacy of Azathioprine (AZA) use in the management in Egyptian patients and to find the correlation between the polymorphism of Nudix Hydrolase15 (NUDT15) gene (rs116855232), The Thiopurine methyltransferase (TPMT) gene (rs1800460) and Inosine Triphosphatase (ITPA) gene (rs1127354) which are involved in the metabolism of the medications utilized in IBD management. Methods: This prospective study was performed in 150 patients with IBD. All patients were treated with 2 mg/kg per day AZA (Imuran, GlaxoSmithKline®) for at least 3 months at therapeutic doses to induce remission. Subsequent treatment of AZA. The minimum follow-up period for those who did not experience ADR was one year. Among the studied patients, one hundred twenty-nine patients were treated with combination regimen of steroids (oral prednisone 1 mg/kg/day). Also, treatment failure was considered among the patients who could not tolerate AZA side effects, or there was no improvement after dose modification. Results: The most identifiable adverse effect among the studied population was anemia followed by leukopenia and myelosuppression. SNPs genotype TPMT (rs1800460) and ITPA gene (rs1127354) were significantly related to adverse effects among IBD patients receiving Azathioprine treatment. There was a lack of any variants in the NUDT15 genotype among the Egyptian population. Conclusion: Further research is required in to clarify the relationship between NUDT15 PGx and AZA-ADRs. The effect of NUDT15 PGx on toxicity and ADRs as yet necessitates to be elucidated. Studies with a larger sample size and involving different ethnicities are also necessary.