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 is a tumor suppressor whose loss of function drives cancer and, when inherited, causes Li-Fraumeni syndrome with high early-life cancer risk. This likely pathogenic Arg280Ser missense change is predicted to impair p53's protective function - consistent with functional assays showing loss of function and its absence from population databases - so it should be treated as conferring Li-Fraumeni syndrome-associated cancer risk.