14 O - New mutation in BRCA 1 gene detected in 3 austrian HBOC families

BRCA1 maps to chromosome region 17q21.1, and mutations in this gene predispose strongly to breast and ovarian cancer. It has recently been isolated and previously it was shown to explain approximately 45 % of all breast cancer families and over 80 % of all families in which both breast and ovarian cancer occur. Women, who carry mutations in the BRCA1 gene, have a lifetime risk of 85 % to develop breast cancer and 60% for ovarian cancer. Austrian HBOC families with several breast- and ovarian cancer cases were selected for mutation screening on the basis of positive LOD scores. Mutation sceening was performed by protein truncation test (PTT). Positive findings were then subjected to DNA sequence analysis. In three until now unrelated families the same mutation could be detected. This mutation in exon 11, 2795delAAAG, has not yet been reported before. The frequency of this mutation in the Austrian population will be of further interest.