Screening for a BRCA2 rearrangement in high-risk breast/ovarian cancer families: evidence for a founder effect and analysis of the associated phenotypes

J Clin Oncol. 2007 May 20;25(15):2027-34. doi: 10.1200/JCO.2006.06.9443.


Purpose: BRCA2 rearrangements are rare genetic events. A large BRCA2 genomic insertion was recurrently observed in our participants, and we sought to characterize it at the molecular and phenotypic level.

Patients and methods: We studied 210 high-risk breast/ovarian cancer families. Fifty-three probands were fully screened for BRCA1/2 mutations, and three of 53 had a large insertion in exon 3 of BRCA2. This finding was analyzed by polymerase chain reaction (PCR), reverse transcriptase PCR (RT-PCR), and sequencing. An additional 157 consecutive families were screened for this mutation by a three-step PCR method. Phenotype and haplotype analysis was also performed.

Results: Sixteen BRCA mutations were observed in 19 of 53 patients (36% detection rate). A recurrent Alu motif insertion in position c.156_157 was observed after sequencing of an abnormal fragment obtained after the amplification of BRCA2 exon 3. RT-PCR revealed exon 3 skipping. Screening of this rearrangement identified 14 additional families (out of 157). In total, 17 (8%) of 210 high-risk families ascertained in our clinic were positive for this mutation. Segregation of a common haplotype (from D13S260 to D13S1695) confirmed a common origin, estimated to have occurred 2,400 to 2,600 years ago. The following four cancer phenotypes were observed in the 17 positive families: female breast (n = 9), male breast (n = 4), breast/ovarian (n = 2), and heterogeneous (n = 2). Male breast cancer was more frequently observed in c.156_157insAlu-positive families compared with negative families (23% v 12%, respectively), and 33% of all male breast cancer families with an identified BRCA mutation were c.156_157insAlu positive.

Conclusion: c.156_157insAlu is a founder mutation of Portuguese origin and is the most frequent BRCA2 rearrangement described to date.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • BRCA2 Protein / genetics*
  • Breast Neoplasms / genetics*
  • DNA Mutational Analysis
  • Female
  • Founder Effect*
  • Gene Rearrangement / genetics*
  • Genetic Predisposition to Disease*
  • Genetic Testing
  • Germ-Line Mutation
  • Humans
  • Jews
  • Male
  • Mass Screening
  • Middle Aged
  • Ovarian Neoplasms / genetics*
  • Pedigree
  • Phenotype


  • BRCA2 Protein