Mutations in Cancer Susceptibility Genes
Now let's look at what a difference an allele can make. Another contributor to cancer risk comes from cancer-predisposing germline mutations called cancer susceptibility genes. Persons with susceptibility mutations carry these altered alleles in every cell in their bodies. Here are examples of the mutations seen in the BRCA2 and BRCA1 breast cancer susceptibility genes. Inheriting these mutated alleles greatly increases a person's lifetime cancer risk. This may explain why cancers linked to germline mutations in susceptibility genes often occur at an earlier age and in multiple sites.