[Familial predisposition to breast cancer. Review].

An estimated 20% of all breast cancer or ovarian and breast cancer cases have familial aggregation. Today it is known that approximately 10% of these cases are attributable to inherited mutations of a predisposition gene that confers a high risk of developing the disease. Several genes have been identified that differ in the risks which they determine, the proportion of cases they explain and the other cancers they may cause. Out of all the genes reported so far, BRCA1 and BRCA2 are the most important ones. The mutations in the remaining genes are rare or involve moderate or low risks. The possibility to detect breast and/or ovarian cancer susceptibility genes in high risk families poses serious challenges that must be faced by health professionals related with this field.