Loss of heterozygosity at BRCA2 in a ductal carcinoma in situ and three invasive breast carcinomas in a family with a germline BRCA2 mutation.

We have examined a family with a germline BRCA2 mutation in three cases of invasive breast cancer and one case of ductal carcinoma in situ (DCIS). Loss of heterozygosity (LOH) has been demonstrated at the BRCA2 locus in all cases. This result may suggest that the germline mutation in BRCA2 is the initiating step of DCIS and support the theory that DCIS is a precursor of invasive breast carcinoma in hereditary breast cancer.