BRCA2 mutation analysis of 87 Spanish breast/ovarian cancer families.

It is estimated that about 5% -10% of breast cancer (BC) cases is due to inherited predisposition. Early works reported that 45%-50% of site-specific BC families had BRCA1 mutations and 25%-35% BRCA2 mutations. However, these percentages could have been overestimated and likely vary among the populations studied.,We analysed the BRCA2 gene in 87 Spanish breast/ovarian cancer families in which the BRCA1 mutation screening was negative.,We detected 15 (17.2%) disease-causing mutations and 11 polymorphisms and unclassified variants. Four mutations were recurrent, and five were novel. Seven (47%) mutations were found in site-specific female BC families, five (33%) in families with OC cases, and three (20%) mutations in families with male BC cases. There was incomplete penetrance of the mutations in some families, and considerable phenotypic variations with respect to the age of diagnosis and cancer types.,The percentage of mutations detected reinforces the possibility that some of these families have mutations in genes other than BRCA1 or BRCA2 that confer lower BC risks.