BRCA1 and BRCA2 mutations in Russian familial breast cancer.

We have screened index cases from 25 Russian breast/ovarian cancer families for germ-line mutations in all coding exons of the BRCA1 and BRCA2 genes, using multiplex heteroduplex analysis. In addition we tested 22 patients with breast cancer diagnosed before age 40 without family history and 6 patients with bilateral breast cancer. The frequency of families with germline mutations in BRCA was 16% (4/25). One BRCA1 mutation, 5382insC, was found in three families. The results of present study, and those of a separate study of 19 breast-ovarian cancer families, suggest that BRCA1 5382insC is a founder mutation in the Russian population. Three BRCA2 mutations were found in patients with breast cancer without family history: two in young patients and one in patients with bilateral breast cancer. Four novel BRCA2 mutations were identified: three frameshift (695insT, 1528del4, 9318del4) and one nonsense (S1099X).