BRCA1 and breast cancer: The Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA) reported a ratio of 3.5:1 excess of BRCA1 CNVs compared to BRCA2, among 18,435 breast cancer cases with BRCA1 PVs and 11,351 with BRCA2, ascertained from 69 centers in 49 countries on 6 continents.