SMARCB1 rs779769475: Understanding Rhabdoid Tumor Predisposition
The rs779769475 variant is a rare genetic change located in the SMARCB1 gene. It is identified as a pathogenic marker associated with Rhabdoid Tumor Predisposition Syndrome 1 (RTPS1), a condition that increases the risk of developing specific types of aggressive tumors.
What each genotype means
Typical SMARCB1 genotype
This genotype represents the most common genetic sequence found at this location in the SMARCB1 gene. It is not associated with the increased risk of rhabdoid tumor predisposition syndrome 1.
This is the predominant genotype observed across all global populations.
Rare variant carrier
This genotype indicates the presence of a rare variant in the SMARCB1 gene. Research identifies this specific variant as a potential pathogenic marker for rhabdoid tumor predisposition syndrome 1, though the evidence strength remains limited. Individuals with this finding should consult with a genetic counselor or medical specialist to discuss clinical implications.
This genotype is extremely rare and is not typically found in the general population.
Rare variant homozygous
This genotype indicates the presence of two copies of the rare variant in the SMARCB1 gene. While this variant is linked to rhabdoid tumor predisposition syndrome 1, the clinical significance of carrying two copies is not well-characterized in current literature. Please discuss this result with a healthcare provider or genetic counselor for personalized context.
This genotype is exceptionally rare and has not been established as a common occurrence in any known population.
What is the rs779769475 Variant?
The rs779769475 variant is a specific change in the DNA sequence of the SMARCB1 gene, which is located on chromosome 22. In genetics, a single nucleotide polymorphism (SNP) like this represents a variation at a single position in the genome. While many variants are common and have no impact on health, rs779769475 is classified as a pathogenic variant. This means that when this specific change is present in the germline—the DNA inherited from parents—it is associated with an increased risk for certain health conditions. Because this variant is extremely rare in the general population, it is not typically found in standard consumer genetic screening panels. Its identification usually occurs in a clinical setting, often following the diagnosis of a rhabdoid tumor in a child or through family history investigations.
The Role of the SMARCB1 Gene
The SMARCB1 gene provides instructions for making a protein that is a core component of the SWI/SNF chromatin remodeling complex. This complex acts like a master switch for gene expression, helping to control how DNA is packaged and read within the cell. By regulating the accessibility of DNA, the SMARCB1 protein functions as a tumor suppressor. Tumor suppressors are essential for preventing cells from growing and dividing too rapidly or in an uncontrolled way. When the SMARCB1 gene is mutated or inactivated, the resulting protein may not function correctly. This loss of function can disrupt the cell's ability to regulate its own growth, which is a critical step in the development of various cancers, including rhabdoid tumors. These tumors are rare, aggressive malignancies that can occur in the brain, spinal cord, or kidneys.
Research and Clinical Significance
Research has established a clear link between pathogenic germline variants in SMARCB1 and Rhabdoid Tumor Predisposition Syndrome 1 (RTPS1). Individuals with this syndrome have a significantly higher risk of developing rhabdoid tumors compared to the general population. The evidence for this association is strong in the context of clinical genetics, where the presence of such a variant is used to guide medical surveillance and genetic counseling for affected families. However, it is important to note that the presence of a pathogenic variant does not guarantee that a tumor will develop; rather, it indicates a predisposition. Because the mechanisms by which these variants lead to tumor formation are complex and can involve additional somatic mutations, clinical management is highly individualized. Genetic counseling is essential for families to understand the implications of these findings, including the 50% chance of passing the variant to offspring.
Understanding Your Results
If you or a family member have been identified as a carrier of the rs779769475 variant, it is vital to work closely with a medical geneticist or a genetic counselor. This information is not for self-diagnosis or personal health management. Clinical professionals use this data to determine if increased surveillance or specific screening protocols are necessary. Because this variant is rare and linked to a serious health condition, it requires expert interpretation within the context of your personal and family medical history. You cannot 'treat' or 'change' a genetic variant, but knowing your status can help your healthcare team provide proactive care. Always discuss genetic test results with a qualified clinician who can explain what the findings mean for your specific situation and provide guidance on the next steps for you and your family members.
How common is this variant?
The rs779769475 variant is considered very rare in the general population, with no significant frequency observed across major ancestral groups.
Frequently asked questions
What is Rhabdoid Tumor Predisposition Syndrome 1?
RTPS1 is a hereditary condition caused by pathogenic variants in the SMARCB1 gene. It significantly increases the risk of developing aggressive tumors, particularly in the central nervous system and kidneys.
Is rs779769475 found in common ancestry tests?
No, this variant is extremely rare and is not typically included in standard consumer genetic testing panels. It is usually identified through specialized clinical genetic testing.
Does having this variant mean I will get cancer?
Not necessarily. While the variant increases the risk of developing rhabdoid tumors, it is a predisposition, not a diagnosis. You should discuss your specific risk and surveillance options with a genetic counselor.
Can I change my genotype for this variant?
No, your genetic sequence is inherited and cannot be changed. Genetic testing is used to identify your status so that your healthcare team can provide appropriate medical monitoring.
Sources & further reading
Educational information only, last refreshed 9/22/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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Pathogenic variant associated with Rhabdoid tumor predisposition syndrome 1.
Pathogenic variant associated with Rhabdoid tumor predisposition syndrome 1.
Pathogenic variant associated with Rhabdoid tumor predisposition syndrome 1.