The size of cumulative breast cancer case-control groups was estimated based on the frequency of the deletion in the European population (~11-13% - based on our preliminary results and [18]) and expected effect (OR~1.3 – estimated based on previous studies, i.e., [17, 31]) of the APOBEC3B deletion in order to obtain adequate statistical power (>90%) of the analysis. The gene discussed is APOBEC3B; the disease is breast carcinoma.