The aim of this study was to identify aberrant transcript variants resulting from the alternative splicing of BRCA1 and BRCA2 genes in RNA extracted from blood lymphocytes from women with a family history of and/or early onset breast and/or ovarian cancer, in which genomic pathogenic alterations in BRCA1 and BRCA2 have not been detected by conventional analysis. This evidence concerns the gene BRCA1 and ovarian carcinoma.