Patient 3 presented with bilateral BC at 47, her mother died from pancreas cancer, her maternal grandmother had CRC, her paternal grandmother had BC; she had the MUTYH c.536A>G (p.Tyr179cys), but also a mutation in CHEK2: c.470T>C (p.Ile157Thr) that is known as pathogenic. Here, CHEK2 is linked to breast cancer.