For index cases with established cancer predisposition syndromes—such as Li–Fraumeni syndrome (TP53) or constitutional mismatch repair deficiency (CMMRD, MSH6)—counseling included a structured discussion of the associated cancer risks, current clinical guidelines, and established surveillance protocols (e.g., whole-body MRI for Li–Fraumeni and colonoscopy for CMMRD). This evidence concerns the gene TP53 and cancer.