Germline TP53 mutations are associated with Li-Fraumeni (LFS) and Li-Fraumeni-like syndromes (LFL), characterized by a familial clustering of tumours, with a predominance of soft tissue and bone sarcomas, breast cancers, brain tumours, and adrenocortical carcinomas, diagnosed before the age of 45 years. TP53 germline mutations have also been observed in families at high risk of breast cancer, albeit at very low frequency.
A founder mutation TP53 (NG_017013.2:g.21852G>A, p.R337H) is detected in 0.3% of the general population in southern Brazil. This mutation is associated with an increased risk of childhood adrenal cortical carcinoma (ACC) but is also common in Brazilian LFS/LFL families.
The frequency of TP53 de novo germline mutation ranges between 7 and 20%.

Mutation of the TP53 gene can be found in 50% of human cancer. More than 80% of TP53 mutations are missense mutations that lead to the synthesis of a stable oncogenic protein that accumulates in the nucleus of tumour cells. The frequency of TP53 alterations range from less than 5% in cervical carcinoma to 90% in ovarian carcinoma or Small Cell Lung Cancer (SCLC) but these numbers must be taken with caution due to several factors such as the subtype of the cancer (lung or breast cancer), the stage of the tumour (prostate carcinoma or chronic lymphocytic leukaemia) and exogenous features such as viral or bacterial infection.
Two international consortiums have reported the sequencing of more than 10.000 tumour genomes and confirmed that the TP53 gene is the most frequently mutated gene in human cancer. TP53 mutations are strongly associated with tumours with high chromosomal instability.
Cancer specific driver genes can be noticed: APC in colorectal carcinoma (violet); VHL in kidney cancer (green) or PTEN and PIK3CA in endometrial carcinoma (green and red)
Molecular epidemiology studies demonstrate a link between exposure to various types of carcinogens, specific mutational events in the TP53 gene and the development of specific cancers.
Lung cancer
TP53 mutations in lung cancer are mostly GC to TA transversions, with a rate of transition mutations lower than in other cancers. There is a strong correlation between the frequency of these GC to TA transversions and lifetime cigarette smoking. This high frequency of GC to TA transversions has not been detected for other cancers such as colon, breast, ovary or brain cancer, which are not directly associated with smoking. This observation is compatible with the role of exogenous carcinogens such as benzo(a)pyrene in lung cancer. After metabolic activation, one of the derivative products of benzo(a)pyrene, the prime carcinogen in cigarette smoke, binds predominantly to guanine and gives rise to specific G-C to T-A transversions. Exposure of cells to benzo(a)pyrene lead to the formation of adducts at codon 157, 248 and 273 in the p53 gene. These positions are the major mutational hotspots in human lung cancer but not in other cancers. The p53 gene is one of the targets of carcinogens found in tobacco.
Liver cancer
There is a strong association between infection with hepatitis B virus and hepatocellular carcinoma. Aflatoxin B1 has been considered to be a significant etiological factor for liver cancer in Western Africa and Asia. Aflatoxins are compounds produced by fungal strains (such as Aspergillus flavus for aflatoxins B1) that are known food contaminants in these countries. Aflatoxins are highly carcinogenic in experimental animals, producing liver tumours in newborn mice, rats, fish, ducks and monkeys.
Worldwide epidemiological studies showed that a specific mutation at codon 249 (c.747G>T, p.R249S) is specifically found in liver cancer from countries in which food was contaminated by aflatoxin B1. In countries which do not consume contaminated food (including Europe and the USA), TP53 mutations are scattered along the central part of p53, as for the other types of cancer. In vitro and in vivo analysis showed a specific binding of aflatoxin B1 to codon 249 of the TP53 gene.
Bladder cancer
Aristolochic acid (AA), a common ingredient in many Chinese herbs, is a powerful nephrotoxin and human carcinogen associated with chronic kidney disease and upper urinary tract urothelial carcinomas including bladder cancer. AA exposure is also associated with Balkan endemic nephropathy (BEN) similarly characterized by kidney failure and a high frequency of transitional cancer of urothelial tracts including bladder, renal pelvis and ureters.
TP53 mutation from patients exposed to AA display a high frequency A:T-to-T:A transversions, a mutational signature associated with AA which forms a covalent adduct with adenine that leads to this transversion.
Skin cancer
Ultraviolet (UV) light induces specific DNA damage such as cyclobutane pyrimidine dimers (CPDs) and pyrimidine(6-4)pyrimidine photoproducts (64PPs) at dipyrimidine sites, where two pyrimidine (Py) bases are juxtaposed in tandem in the nucleotide sequence of DNA. If left unrepaired, this lesion leads to specific types of mutation: base substitutions of cytosine (C) → thymine (T) at dipyrimidine sites and CC → TT tandem base substitutions. These two types of mutation are called UV signature and their detection suggests past exposure to UV. In skin cancer such as squamous cell carcinoma (SCC) and basal cell carcinoma (BCC), the frequency of TP53 is high (70 to 80%) with more than 15% of tandem mutations (less than 1% for other cancer types).
Colorectal or brain cancer
The cytosine-guanine (CpG) dinucleotide is a hotspot for pathological mutations in the human genome. This hypermutability is due to its role as the major site of cytosine methylation with the attendant risk of spontaneous deamination of 5-methylcytosine (5mC) to yield C → T and G → A transitions. Most TP53 hotspots for mutations in colorectal or brain cancer are located at CpG sites with a mutation spectrum compatible with 5-methylcytosine deamination. These hotspot codons, CGN at positions 175, 248 or 273, encode arginine residues important for TP53 structure and/or activity. It is interesting to note that arginine can also be encoded by AGG and AGA that have the same frequency of usage in human but are not targeted by methylation. It has not yet been determined whether or not there is a specific selection to keep CGN in the TP53.