Prevalence of BRCA1 founder mutations in western Poland.

The frequency of three BRCA1 founder mutations was examined in a group of Polish breast/ovarian cancer patients and women at increased risk of these cancers based on family history. Among the 15 mutations found (5385-5386insC, 187-188delAG, and 4154delA), eight were detected in women with a low or moderate family history. The frequency of the IVS20+48ins12 variant was also analyzed and its distribution within risk groups argues against its involvement in cancer predisposition.