In order to simulate a realistic breast cancer predisposition case-control study we randomly split each of the original cohorts in a case (1000GP: 905, Iberian: 389 samples) and a control group (1000GP: 905, Iberian: 778 samples), and, in the case group samples, added ClinVar and HGMD risk variants to the genes BRCA2, BRCA1, PALB2, BRIP1, CHEK2 and BARD1 using realistic variance explained (VE) rates (see Material and Methods). The gene discussed is BRCA1; the disease is breast cancer.