The differential relative usage of these enzymes can explain why homozygous long deletion of TDP2 gene is seen more frequently in the prostate cancer than breast cancer (TCGA database) (Sasanuma et al., 2018), while defects in BRCA1 increase the incidence of the breast cancer to a greater extent than that of the prostate cancer (Roy, Chun, & Powell, 2012). The gene discussed is BRCA1; the disease is breast cancer.