NUDT15 and Decreased total leukocyte count: As compared with patients with wild-type NUDT15, both NUDT15 variations had a combined sensitivity and specificity of 68.4% and 94%, respectively (OR = 33.80, 95% CI 8.99–127.05, p < 0.001), for predicting thiopurine-induced leukopenia as well as a shorter onset to leukopenia (median onset [months] 2.0 vs. 5.5; p = 0.045).