title: Founder BRCA1 and BRCA2 mutations in early-onset French Canadian breast cancer cases unselected for family history.
abstract: Recently, founder BRCA1 and BRCA2 mutations were identified in Canadian breast cancer and breast-ovarian cancer families of French ancestry. The presence of a breast cancer case diagnosed at younger than 36 years of age was strongly predictive of the presence of any founder mutation screened. Here we report the occurrence of founder BRCA1 and BRCA2 mutations in a series of 61 French Canadian women with invasive breast cancer diagnosed at age 40 or younger, unselected for family history of breast and ovarian cancer. Germline mutations in BRCA1 (n = 4) and BRCA2 (n = 4) were identified in 8 of 61 (13%) cases. All BRCA1 mutations were found in invasive ductal carcinomas, the most common histologic type of tumor in this series. In contrast, the BRCA2 mutations were found in tumors of various histologic types: two ductal carcinomas, a tumor containing both ductal and lobular histologic types and an invasive lobular carcinoma. Of the 37 women with at least one first-, second- or third-degree relative with breast or ovarian cancer and the 24 women with no history of these cancers, 7 (19%) and 1 (4%), respectively, were mutation carriers. The seven mutation carriers with a family history of cancer had at least one first-, second- or third-degree relative with a breast cancer diagnosis at less than 51 years of age. The identification of founder BRCA1 and BRCA2 mutations in young-onset breast cancer cases unselected for family history can facilitate carrier detection when the expected yield of a comprehensive screen may be low.
authors: Medical Genetics, Room L10-120, Montréal General Hospital Research Institute, 1650 Cedar Avenue, Montréal, Québec, H3G 1A4, Canada. tonin@med.mcgill.ca
authors: P N
authors: PN
authors: Tonin
authors: C
authors: C
authors: Perret
authors: J A
authors: JA
authors: Lambert
authors: A J
authors: AJ
authors: Paradis
authors: T
authors: T
authors: Kantemiroff
authors: M H
authors: MH
authors: Benoît
authors: G
authors: G
authors: Martin
authors: W D
authors: WD
authors: Foulkes
authors: P
authors: P
authors: Ghadirian
mesh_terms: D000328:Adult; D019313:BRCA1 Protein / Q000235:genetics*; D024682:BRCA2 Protein; D001943:Breast Neoplasms / Q000208:ethnology / Q000235:genetics*; D002170:Canada / Q000453:epidemiology / Q000208:ethnology; D004252:DNA Mutational Analysis; D005260:Female; D018703:Founder Effect; D005787:Gene Frequency; D006801:Humans; D009154:Mutation; D009363:Neoplasm Proteins / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics*
chemical_list: D019313:BRCA1 Protein; D024682:BRCA2 Protein; D009363:Neoplasm Proteins; D014157:Transcription Factors