BRCA2 and breast cancer: BRCA1 gene, located in chromosome 17 (locus: 17q12-q21), was identified in 1990 after studying 23 families with a total of 143 cases of breast and ovarian cancer 16, while BRCA2 gene was identified in 1994 in chromosome 13 locus:13q12-q13 through a study that analyzed 15 families at high risk of familial breast cancer, including male cases 17-.19