TP53 rs121912655: Understanding the p.Arg248Gln Variant
The rs121912655 variant in the TP53 gene, also known as p.Arg248Gln, is a rare germline mutation associated with Li-Fraumeni syndrome. This condition significantly increases the lifetime risk of developing various early-onset cancers due to impaired tumor suppressor function.
What each genotype means
Typical TP53 function
This genotype represents the common, wild-type sequence of the TP53 gene. Individuals with this profile do not carry the specific pathogenic variant associated with Li-Fraumeni syndrome at this location.
This is the most common genotype found in the general population across all ancestries.
Li-Fraumeni syndrome predisposition
This genotype indicates the presence of the p.Arg248Gln pathogenic variant, which impairs the DNA-binding capability of the TP53 protein. This variant is associated with Li-Fraumeni syndrome, a condition that significantly increases the lifetime risk of developing various early-onset cancers. Individuals with this result should consult with a genetic counselor or medical specialist to discuss appropriate clinical surveillance and management.
This is an extremely rare germline allele that is not typically found in the general population.
Li-Fraumeni syndrome predisposition
This genotype indicates the presence of two copies of the p.Arg248Gln pathogenic variant. Because TP53 is a critical tumor suppressor gene, this status is associated with a severe predisposition to early-onset cancer. Individuals with this result should seek immediate consultation with a medical geneticist or oncologist for comprehensive clinical evaluation and management.
This homozygous genotype is exceptionally rare and essentially absent from general population databases.
What is the rs121912655 Variant?
The rs121912655 variant is a specific genetic change located within the TP53 gene, which is found on chromosome 17. In scientific literature, this variant is often referred to as p.Arg248Gln, indicating that at position 248 of the protein, the amino acid arginine is replaced by glutamine. This change occurs in a critical region of the gene known as a "hotspot" for mutations. Because this variant alters the sequence of the protein, it is classified as a missense mutation. It is recognized by clinical genetics databases as a pathogenic variant, meaning it is strongly associated with a hereditary cancer-predisposing syndrome. When this variant is present in the germline—meaning it is inherited or occurred in the egg or sperm—it is considered a primary genetic driver of Li-Fraumeni syndrome, a condition characterized by a high predisposition to developing multiple types of cancer throughout a person's life.
The Role of the TP53 Gene
The TP53 gene provides instructions for making a protein called tumor protein p53. This protein acts as a tumor suppressor, which means it helps regulate cell division and prevents cells from growing or dividing too rapidly or in an uncontrolled way. Often described as the "guardian of the genome," the p53 protein plays a vital role in monitoring DNA integrity. If DNA damage is detected, the protein can trigger mechanisms to repair the damage or, if the damage is too severe, initiate programmed cell death, known as apoptosis. By controlling these processes, the p53 protein prevents the accumulation of mutations that could lead to tumor formation. When a variant like rs121912655 impairs the DNA-binding capability of this protein, the cell loses its ability to effectively manage these critical safety checks, which can lead to the development of malignant tumors.
Clinical Associations and Evidence
Research consistently associates the rs121912655 variant with Li-Fraumeni syndrome (LFS). The evidence for this association is strong, with the ClinGen TP53 Variant Curation Expert Panel classifying it as pathogenic. Individuals who carry this variant have a significantly elevated risk of developing a wide spectrum of cancers, including breast cancer, brain tumors, sarcomas, and adrenocortical carcinomas, often at an unexpectedly early age. It is important to note that while the variant is a strong indicator of cancer predisposition, the clinical expression can be variable. Not every individual with the variant will follow the same disease trajectory, and "penetrance"—the likelihood that a person with the variant will actually develop the associated condition—can be influenced by other genetic and environmental factors. Clinicians use this information to guide surveillance strategies for early cancer detection in affected families.
Population Frequency
The rs121912655 variant is considered an extremely rare germline allele in the general population. Because it is associated with a serious health condition, it is not typically found at high frequencies in large, unselected population databases. Its presence is usually identified in the context of clinical genetic testing for individuals or families with a significant history of early-onset cancers. Due to its rarity, it is not a variant that would be expected in the general public without a specific clinical indication. If you or a family member have been identified as a carrier of this variant, it is essential to consult with a genetic counselor or a medical oncologist. These professionals can provide context regarding the specific risks, discuss appropriate screening protocols, and help navigate the complexities of hereditary cancer syndromes.
What You Can Do With This Information
Genetic information regarding pathogenic variants like rs121912655 is highly sensitive and carries significant medical implications. If you have received a report indicating the presence of this variant, the most important step is to discuss the results with a qualified healthcare provider, such as a genetic counselor or a specialist in hereditary cancer. They can help interpret what this means for your personal health and the health of your family members. This information is not a diagnosis of cancer, but rather a tool for risk assessment and proactive health management. You should never make medical decisions, such as starting or stopping treatments or undergoing prophylactic surgeries, based solely on genetic reports without professional clinical guidance. Genetic testing for such variants is a complex process that requires expert interpretation to ensure that medical management is tailored to your specific clinical history.
How common is this variant?
The rs121912655 variant is an extremely rare germline allele, typically identified only in clinical settings involving families with a history of Li-Fraumeni syndrome.
Frequently asked questions
Is rs121912655 the same as Li-Fraumeni syndrome?
The rs121912655 variant is a known pathogenic mutation that causes Li-Fraumeni syndrome. However, a diagnosis of the syndrome is based on clinical criteria, including personal and family cancer history, not just the presence of the variant.
Does having this variant mean I will definitely get cancer?
While this variant significantly increases the lifetime risk of developing various cancers, it does not guarantee that an individual will develop cancer. Many factors, including other genetic modifiers and environmental exposures, influence the actual risk.
Can I test for this variant at home?
Clinical-grade genetic testing for pathogenic variants like rs121912655 should be performed through a certified medical laboratory under the supervision of a healthcare provider. Direct-to-consumer tests may not be designed to detect or accurately report on such rare, high-impact clinical variants.
What should I do if I have this variant?
If you are identified as a carrier, you should consult with a genetic counselor or an oncologist who specializes in hereditary cancer syndromes. They will help you develop a personalized surveillance plan for early cancer detection.
Sources & further reading
Educational information only, last refreshed 9/29/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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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.
Li-Fraumeni syndrome missense variant (p.Arg248Trp) causing loss of tumor suppressor function and multi-cancer predisposition.
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.