TP53 and breast cancer: The MCG-breast and FH series samples also underwent analysis of 7 additional breast cancer predisposition genes: 5 rare, higher penetrance predisposition genes (PALB2, TP53, CDH1, PTEN, and STK11) and 2 more common, lower penetrance predisposition genes (ATM and CHEK2).39 One individual (0.05%) in the FH series had a mutation in a higher penetrance non-BRCA predisposition gene compared with 24 patients (2.0%) in the MCG-breast group.