TP53 rs121913279: What Your Genotype Means
The rs121913279 variant is an extremely rare missense alteration located in the TP53 gene on chromosome 17. It results in a p.Arg248Trp amino acid substitution within a critical DNA-binding hotspot of the p53 tumor suppressor protein. When inherited in the germline, this change is classically associated with Li-Fraumeni syndrome, a condition characterized by a high lifetime predisposition to multiple cancers.
What each genotype means
Typical cancer risk profile
You carry two reference copies of the TP53 gene at this position. This result means you do not have the high-risk p.Arg248Trp variant associated with Li-Fraumeni syndrome. Your baseline risk for developing cancers remains similar to that of the general population.
Carried by more than 99.99% of individuals across all global populations.
High multi-cancer predisposition
You carry one copy of the pathogenic p.Arg248Trp missense variant in TP53, which causes Li-Fraumeni syndrome. In clinical studies, this alteration severely impairs the tumor-suppressing function of the p53 protein and is associated with a significantly elevated lifetime risk of developing multiple primary cancers, such as sarcomas, breast cancer, brain tumors, and adrenocortical carcinomas. Individuals carrying this genotype typically participate in specialized high-risk cancer screening protocols under genetic counseling.
Extremely rare, observed in less than 1 in 100,000 individuals in the gnomAD database.
Severe cancer predisposition
You carry two copies of the pathogenic p.Arg248Trp variant in TP53. Biallelic germline inheritance of severe TP53 missense variants is exceptionally rare and typically incompatible with normal embryonic or early childhood development due to total loss of p53 tumor-suppressing function. Individuals with two mutated alleles face an extraordinarily high risk of very early-onset childhood malignancies.
Extremely rare to virtually absent in general population databases.
Variant Classification and Genomic Location
The single nucleotide polymorphism designated rs121913279 represents a coding alteration located on human chromosome 17 at 17p13.1 within the TP53 gene. In the standard genomic reference sequence, the typical allele at this position is a cytosine (C), whereas the variant allele introduces a thymine (T). This specific transition (c.742C>T) alters the underlying codon from encoding arginine to tryptophan at position 248 of the peptide chain, designated as p.Arg248Trp. Codon 248 is widely recognized in human oncology as a critical mutational hotspot. The amino acid arginine normally makes direct contact with target DNA sequences, stabilizing the p53 protein's architectural interface. Replacing this basic, positively charged residue with a bulky, aromatic tryptophan disrupts critical structural bonds, fundamentally altering the protein's ability to bind DNA and regulate downstream target genes effectively.
Biological Role of the TP53 Tumor Suppressor
The TP53 gene encodes the tumor protein p53, often termed the 'guardian of the genome.' This master transcription factor coordinates essential cellular responses to cellular stress, DNA damage, and oncogenic signaling. When healthy cells encounter genomic lesions, p53 accumulates rapidly within the nucleus, activating distinct programs that stall the cell cycle at critical checkpoints to allow for repair. If cellular damage is extensive and irreparable, p53 prompts programmed cell death (apoptosis) or permanent cell-cycle arrest (senescence) to prevent unstable cells from proliferating. By eliminating aberrant cells before they can acquire additional mutations, p53 acts as a vital barrier against tumorigenesis. Structural alterations like p.Arg248Trp severely impair these protective functions, frequently leading to a loss of tumor suppressor capability or even a dominant-negative interference with normal cellular proteins.
Clinical Associations and Strength of Evidence
Germline occurrence of rs121913279 is clinically linked to Li-Fraumeni syndrome (LFS), an autosomal dominant hereditary cancer predisposition disorder. Extensive evidence cataloged across medical registries and peer-reviewed literature confirms that hotspot missense variants in the TP53 DNA-binding domain confer high penetrance and an elevated lifetime risk for early-onset malignancies. These cancers frequently include soft-tissue and osteosarcomas, premenopausal breast cancers, brain tumors, adrenocortical carcinomas, and acute leukemias. Although somatic mutations at codon 248 are exceedingly common within sporadic tumor tissues, genuine constitutional (germline) inheritance is far less frequent. Clinical geneticists emphasize that while the pathogenic association between TP53 hotspot mutations and familial cancer risk is supported by definitive clinical research, the exact age of onset and tumor spectrum can vary considerably based on modifier genes, lifestyle factors, and individual biology.
Population Frequency and Context
In general human populations, constitutional alleles for rs121913279 are exceptionally uncommon. Data compiled by large reference catalogs, including the Genome Aggregation Database (gnomAD), show that the alternate T allele occurs at a frequency far below 0.00001, making it virtually absent among healthy, unrelated background cohorts. Because this variant is subject to intense negative selective pressure due to its profound impact on early-life fitness, it does not achieve high prevalence in any major global ancestry group. Most observed instances arise either as rare, inherited familial alleles tracked across multiple generations or as spontaneous, de novo mutations appearing in an individual for the first time during early embryogenesis. Because it is so rare, population-level screening rarely detects the variant outside of clinically directed multi-gene hereditary cancer panels.
Actionable Insights and Next Steps
Discovering an alteration at rs121913279 on a commercial or consumer genetic test requires careful clinical contextualization and confirmatory diagnostic testing. Consumer microarray platforms can produce false positives on very rare single nucleotide variants; therefore, validation using Sanger sequencing or clinical next-generation sequencing in an accredited clinical laboratory is essential. Furthermore, blood-based sequencing in older adults can sometimes detect somatic changes known as clonal hematopoiesis of indeterminate potential (CHIP), rather than true hereditary germline mutations. If a constitutional TP53 mutation is clinically validated, established surveillance programs, such as the Toronto Protocol, utilize annual whole-body MRI, brain MRI, and dedicated organ screening to detect tumors at their earliest, most treatable stages. Individuals who carry or suspect this alteration should consult a certified genetic counselor or medical geneticist.
How common is this variant?
The rs121913279 variant is exceptionally rare across all global ancestries, with an overall allele frequency reported at less than 0.00001 in public aggregators such as gnomAD. Almost all individuals in the general population carry the homozygous CC genotype.
Frequently asked questions
What is the rs121913279 variant in TP53?
The rs121913279 variant is a very rare DNA change in the TP53 gene that switches an amino acid at position 248 from arginine to tryptophan. This alteration impairs the p53 protein's ability to act as a tumor suppressor and control cell division. When inherited, it is classically linked with Li-Fraumeni syndrome.
Does carrying rs121913279 mean I will definitely get cancer?
Carrying a confirmed germline mutation significantly elevates the lifetime likelihood of developing certain cancers, but it does not make cancer inevitable. In genetics, this is called incomplete penetrance, meaning additional genetic, biological, and environmental factors influence whether a tumor ever forms.
Can consumer DNA tests accurately detect rs121913279?
Consumer DNA tests are not optimized for detecting extremely rare pathogenic mutations and can occasionally generate false-positive calls. In addition, DNA tests performed on blood samples can detect age-related mutations confined only to blood cells (CHIP) rather than inherited DNA. Any positive finding must be confirmed using a dedicated clinical test ordered by a healthcare provider.
What medical steps are recommended if this variant is confirmed?
If a certified laboratory confirms an inherited TP53 variant, clinical guidelines recommend enrolling in high-risk cancer screening protocols, such as the Toronto Protocol. These surveillance programs include regular whole-body magnetic resonance imaging (MRI), dedicated breast imaging for women, and specialized pediatric monitoring to detect any growths as early as possible.
Sources & further reading
Educational information only, last refreshed 9/13/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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Pathogenic missense variant (p.Arg248Gln) associated with Li-Fraumeni syndrome.
Functional codon 72 polymorphism (Arg72Pro) affecting apoptotic capability and associated with differential susceptibility to multiple cancer types.
Functional 3' UTR polyadenylation signal polymorphism altering TP53 transcription termination, showing population-specific baseline carrier frequencies across global groups.
Pathogenic hotspot variant (p.Arg273His) in TP53 predisposing carriers to early-onset sarcomas, breast cancers, and leukemias.
Synonymous and regulatory variant in linkage with TP53 codon 72 that modulates blastocyst implantation competence and the risk of recurrent implantation failure.
3' UTR hypomorphic variant in TP53 that impairs proper polyadenylation and significantly confers elevated risk for basal cell carcinoma, glioma, and other cancers.