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 the most frequently mutated gene in human cancers, and inherited variants cause Li-Fraumeni syndrome with markedly elevated early-onset cancer risk. The VUS classification reflects strong functional evidence that p.(Gly266Val) abolishes p53 transactivation, tempered by the absence of clinical observations (de novo status, segregation, or phenotype) needed to confirm pathogenicity. Definitive interpretation will require additional clinical or functional evidence.