Somatic mutations in the BRCA1 gene in Chinese sporadic breast and ovariancancer

Inherited mutations in the BRCA1 gene confer increased susceptibility to br east and ovarian cancer. Its role in sporadic carcinogenesis is not well de fined. Somatic mutations in breast cancers have not been reported and to da te there are only three reports of somatic mutations in sporadic ovarian ca ncers. To investigate the contribution of BRCA1 mutations to sporadic breas t and ovarian cancer in the Chinese population, we analysed 62 samples from Chinese women using the protein truncation test. There were 40 cases of br east cancer under age 50 and 22 cases of ovarian cancer, all unselected for family history. There was no age selection for the ovarian cancers. We fou nd two somatic BRCA1 mutations in exon 11, one in a breast cancer and the o ther in an ovarian cancer, both of which result in truncated proteins. Our results indicate that somatic BRCA1 mutations, like somatic mutations in th e BRCA2 gene, though very rare, can be found in both breast and ovarian can cers and support a tumor suppressor function for BRCA1 in sporadic tumors.