The odds of developing leukopenia in TPMT polymorphism were non-significant (0.77, 95% CI:0.0822 to 7.2134, P = 0.819) but were significantly higher in those with NUDT15 polymorphism (3.5933, 1.1041 to 11.6951, P value: = 0.0336). The gene discussed is NUDT15; the disease is Decreased total leukocyte count.