BRCA1/2 mutations in Swiss patients with familial or early-onset breast and ovarian cancer.

Questions Under Study: Germ-line alterations in BRCA1 and BRCA2 genes account for 30-50% of all forms of familial breast and ovarian cancer syndromes. Specific mutations in specific populations and ethnic groups have been identified in BRCA1 and BRCA2. However, it is not known whether such specific mutations prevail in the Swiss population.

Methods: We started to screen patients with primary breast and ovarian cancer and a strong family history of both cancers by sequencing the full-length coding regions of BRCA1 and BRCA2.

Results: With the selection criteria used in this study we identified 19 mutations in the first 38 patients screened (50%). These mutations were either defined as deleterious and resulted in a protein truncation (n = 10) or were defined as unclassified variants (n = 9). One novel truncating mutation was found in BRCA2 and two novel unclassified variants were detected in BRCA1. These three mutations are not described in the BIC and HGMD databanks.

Conclusions: We detected three unknown mutations among 38 patients in a Swiss study of BRCA1/2 mutation patterns. One of these novel mutations is clearly deleterious as it leads to protein truncation at nucleotide 133 of BRCA2.