A large deletion disrupts the exon 3 transcription activation domain of the BRCA2 gene in a breast/ovarian cancer family.

We describe the identification of a large deletion in the BRCA2 gene as the disease-causing mutation in a Swedish breast/ovarian cancer family. The 5068-bp deletion encompassed the 3' region of exon 3, including the 3' splice site and most of intron 3, and it resulted on the mRNA level in an inframe exon 3 skipping. The junction site also included an insertion of 4 bp (CCAT). The mutation (nt504del5068insCCAT) resulted in a genotype absent of the two transcription activation regions localized to exon 3. The breast cancer phenotype associated with the described mutation resembled the phenotype of breast cancer found in both BRCA1 and BRCA2 mutation carriers. This is the first report of a large deletion as the disease-causing mutation in the BRCA2 gene.