BRCA1 and breast cancer: Since it is well established that the residual familial risk of breast cancer, not caused by BRCA1 or BRCA2 genes, could be explained by a polygenic or high-risk genes heterogeneity model [72,73], we selected individuals affected with breast cancer without mutations in BRCA1/2 genes from high-risk families (one individual per family), in order to increase the power of the study to find genetic variants involved in breast cancer susceptibility.