TP53 encodes the p53 protein, a critical tumor suppressor that acts as a transcription factor to protect cells from damage. When activated by cellular stress such as DNA damage, p53 triggers responses including DNA repair, cell cycle arrest, and programmed cell death (apoptosis) to prevent the propagation of damaged cells. TP53 is the most frequently mutated gene in human cancers, and loss of its function contributes to tumor development, invasion, drug resistance, and genomic instability. Inherited mutations in TP53 cause Li-Fraumeni syndrome, a rare hereditary condition that greatly increases the risk of developing multiple types of cancer at a young age.

TP53 encodes the p53 tumor suppressor, and inherited loss-of-function mutations cause Li-Fraumeni syndrome with markedly elevated, early-onset cancer risk. This variant is classified Likely Pathogenic: it is non-functional in transactivation assays and absent from population databases, indicating impaired p53 tumor-suppressor activity consistent with TP53-associated cancer susceptibility.