BRCA1 and breast carcinoma: This information suggests that the four mismatch repair genes are better described as intermediate risk genes whereas genes like APC or BRCA1 are considered high risk genes linked to colorectal cancer (APC PVs are associated with almost complete penetrance and BRCA1 PVs are very high at ~ 75% at 70 years of age) and breast cancer [15, 16], respectively.