When investigated by the TPMT*1/*3C genotype, the heterozygous patients (10/13; 76.92%) more frequently presented with leukopenia (WBC < 2000 cell/mm3) when compared with homozygous wild type patients (39/87; 44.83%) with an OR of 4.10 (95% CI, 1.06–15.95, p = 0.031). This evidence concerns the gene TPMT and Decreased total leukocyte count.