NUDT15 and Decreased total leukocyte count: According to CPIC, NUDT15*3 (rs116855232:c.415 C > T) variation of the NUDT15 gene results in absence of function of NUDT15 enzyme which results in accumulation of the toxic metabolites, indicating that individuals carrying this variant are likely to exhibit drug induced toxicities such as leukopenia, alopecia, hepatic toxicity, pancreatitis and gastrointestinal toxicity, when treated with thiopurine drugs [17].