Although this method cannot differentiate NUDT15 *1/*2 and NUDT15 *3/*6 diplotypes, it provides clinical information whether patients are wildtype or non-wildtype for NUDT15 genotype, allowing clinicians to adjust the thiopurine dose for the treatment of leukemia and IBD to avoid adverse effects of myelotoxicity. This evidence concerns the gene NUDT15 and inflammatory bowel disease.