TP53 gene

Last reviewed 06/2022

TP53 is a tumour suppressor gene that causes Li-Fraumeni syndrome and affects adults and children

  • highly penetrant gene predisposes for a wide spectrum of tumours, including sarcomas, adrenocortical carcinomas, brain cancer, and very early onset breast cancer
    • TP53 gene provides instructions for making a protein called tumor protein p53. This protein acts as a tumor suppressor
    • majority of TP53 mutations result in the substitution of single aminoacids in the central region of the p53 protein, generating a spectrum of variants ('mutant p53s', for short)
      • these mutants lose the normal p53 oncosuppressive functions to various extents but can also acquire oncogenic properties by gain-of-function mechanisms
    • most cancers are manifested from birth through late adulthood
    • taking into account the tissue and organ specificity of tumors, breast cancer is the single most frequent event in Li-Fraumeni syndrome, accounting for >25% of all tumors in affected families

  • TP53 mutation carriers face a lifetime cancer risk that exceeds 90%

  • patients with Li-Fraumeni syndrome have an abnormal response to low-dose radiation
    • radiation in these patients should be avoided as a therapeutic approach because of the increased secondary tumour risk

  • breast cancer is the most frequent malignancy among female TP53 mutation carriers, with approximately 5% of these cases being diagnosed before the age of 30
    • Li-Fraumeni syndrome accounts for a small fraction of breast cancer cases (approximately 0.1%)
      • however TP53 mutation carriers have from an 18- to 60-fold increased risk for early onset breast cancer (diagnosed before the age of 45) when compared to the general population

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