Final answer:
Li-Fraumeni syndrome is caused by mutations in the p53 gene, which is involved in DNA damage repair.
Step-by-step explanation:
Li-Fraumeni syndrome is a rare hereditary disorder that predisposes individuals to cancer. It is caused by mutations in the p53 gene, which is a tumor suppressor gene involved in DNA damage repair. When the p53 protein is damaged or mutated, it cannot properly detect and repair errors in the genomic DNA, leading to the accumulation of mutations and an increased risk of tumor formation.