Genetic evaluation based on family history and Her2 status correctly identifies TP53 mutations in very early onset breast cancer cases.

Currently, hereditary breast cancer is being attributed to more than 20 genes of differing penetrance. Although BRCA1 and BRCA2 are still the genes of reference for breast cancer susceptibility, extreme breast cancer phenotypes may be the result of deleterious alleles of other genes. Here, we report three families with early-onset breast cancer that were initially referred for BRCA1/BRCA2 genetic testing. They were diagnosed with breast cancer at an extraordinarily early age. On the basis of their extensive family history, which included multiple cancer types, and their Her2 status, they were suspected for Li-Fraumeni syndrome. Indeed, all three probands were found to harbor TP53 tumor suppressor gene mutations. These included p.C275X, described here for the first time, as well as p.R213X and p.Y220C, which have been described in the past. Our conclusion is that decisions on genetic analysis for inherited early onset breast cancer should always be based on detailed pedigree information, combined with Her2 status.