Founder BRCA1 and BRCA2 mutations in French Canadian ovarian cancer cases unselected for family history

The breast cancer susceptibility genes, BRCA1 and BRCA2, differ in their co ntribution to ovarian cancer. Recently, founder mutations in each of these genes were identified in Canadian breast cancer and breast-ovarian cancer f amilies of French ancestry. We have examined the prevalence of the founder mutations in a series of 113 French Canadian women with ovarian cancer unse lected for family history. Germline mutations were found in eight of 99 inv asive carcinomas and in none of the 14 tumors of borderline malignancy. Fiv e cases carried the BRCA1 C4446T mutation and two cases carried the BRCA2, 8765delAG mutation which are the most common mutations that have been descr ibed in French Canadian breast cancer and breast-ovarian cancer families. A ll of these cases reported a family history of at least one first-degree re lative with breast cancer, diagnosed below age 60 years, or with ovarian ca ncer. The identification of founder BRCA1 and BRCA2 mutations in ovarian ca ncer cases unselected for family history can facilitate earlier detection w hen the expected yield of a comprehensive screen may be low.