BRCA2 rs11571833: Understanding the K3326X Variant
The rs11571833 variant, commonly referred to as K3326X, is a specific change in the BRCA2 gene that results in a truncated protein. Research has linked this variant to a small, increased risk for certain cancers, though its clinical significance remains a subject of ongoing study.
What each genotype means
Typical risk profile
This genotype represents the common, non-variant form of the BRCA2 gene at this position. Research indicates this is the baseline state and is not associated with the increased cancer risks linked to the K3326X variant.
This is the most common genotype found in the vast majority of the global population.
Slightly increased cancer risk
This genotype includes one copy of the K3326X variant, also known as p.Lys3326*. Studies suggest this variant is associated with a modest increase in the risk of developing certain cancers, including breast, lung, and upper aerodigestive tract cancers, compared to those without the variant.
The minor allele is carried by approximately 1 in 100 people of European ancestry, though it is extremely rare in some other populations such as the Japanese population.
Increased cancer risk
This genotype consists of two copies of the K3326X variant. Research has linked this variant to a statistically significant, though generally modest, increase in susceptibility to breast, lung, and upper aerodigestive tract cancers. These associations are complex and may be influenced by other factors, including smoking status.
This homozygous genotype is rare, occurring at a low frequency in European, Latin American, and Indian populations.
What is rs11571833?
The variant rs11571833 is a single nucleotide polymorphism (SNP) located within the BRCA2 gene on chromosome 13. In scientific literature, it is frequently identified by the protein-level change it causes, known as K3326X or p.Lys3326*. This notation indicates that the amino acid lysine (K) at position 3326 is replaced by a stop codon (X), which signals the cell to stop building the protein prematurely. Because this occurs near the end of the protein, the resulting BRCA2 molecule is truncated. Unlike some other mutations in the BRCA2 gene that are classified as highly pathogenic and linked to hereditary cancer syndromes, K3326X is often described as a polymorphic stop codon. This means it is a relatively common variation that does not necessarily carry the same high-risk profile as other, more severe BRCA2 mutations.
The Role of the BRCA2 Gene
The BRCA2 gene provides instructions for making a protein that plays a critical role in DNA repair. Specifically, the BRCA2 protein helps repair damaged DNA through a process called homologous recombination, which ensures the stability of the cell's genetic information. When DNA is damaged by environmental factors or errors during cell division, the BRCA2 protein acts as a key component in the repair machinery. If the BRCA2 protein is absent or non-functional, cells may accumulate genetic mutations, which can lead to uncontrolled cell growth and cancer. While the K3326X variant results in a truncated protein, the functional impact of this specific truncation is less severe than that of mutations found in the earlier, more critical regions of the gene. Consequently, the biological consequences of this variant are more nuanced and are still being actively investigated by the scientific community.
Research and Cancer Risk
Scientific studies have investigated the association between the K3326X variant and various cancers, including breast, ovarian, and prostate cancer. Large-scale studies, such as those utilizing the iCOGS dataset, have identified a small, statistically significant increase in the risk of breast cancer for carriers of this variant. However, researchers emphasize that this risk is much lower than that associated with classic, high-penetrance BRCA2 mutations. There is also ongoing debate regarding whether the observed cancer risks are directly caused by the K3326X variant itself or if they are due to linkage disequilibrium—a phenomenon where this variant is inherited alongside other, more harmful mutations nearby. Because the evidence is considered limited or moderate, it is not currently used in the same way as high-risk BRCA2 mutations for clinical decision-making regarding prophylactic surgeries or intensive screening protocols.
Population Frequency
The rs11571833 variant is found across various populations, with a minor allele frequency of approximately 0.01 in European populations. This frequency indicates that while it is not extremely rare, it is not the most common form of the gene either. The distribution of this variant can vary significantly depending on ancestral background, and some studies suggest that its frequency may be higher in specific founder populations. Because it is a relatively common variant compared to rare, high-risk mutations, it is frequently captured in large-scale genomic studies. Understanding its frequency helps researchers determine whether the variant is a rare disease-causing mutation or a more common polymorphism that contributes to a slight increase in susceptibility across the general population.
Interpreting Your Genetic Information
If you have received information about your status for rs11571833, it is important to understand that this variant does not function as a definitive diagnostic tool for cancer. Genetic associations are statistical in nature and describe risks across large groups of people, not individual outcomes. Because the evidence linking K3326X to cancer is considered limited and the effect size is small, it is not typically used to guide specific medical interventions. You should never make changes to your health management or screening schedule based solely on this information. If you are concerned about your family history of cancer or your personal genetic risk, the most appropriate step is to consult with a certified genetic counselor or a healthcare professional. They can help you interpret your results in the context of your overall health, family history, and other lifestyle factors.
How common is this variant?
The rs11571833 variant has a minor allele frequency of approximately 0.01 in European populations, though its prevalence can vary across different ancestral groups.
Frequently asked questions
Is rs11571833 the same as a BRCA2 mutation?
While rs11571833 is a variant within the BRCA2 gene, it is distinct from the high-risk mutations typically associated with hereditary breast and ovarian cancer syndrome. It is often classified as a polymorphic stop codon rather than a highly pathogenic mutation.
Does having the T allele mean I will get cancer?
No. Having the T allele is associated with a small, statistical increase in risk for certain cancers, but it does not mean you will develop cancer. Many factors, including genetics, environment, and lifestyle, contribute to cancer risk.
Should I get extra cancer screenings if I have this variant?
Clinical guidelines for cancer screening are generally based on family history and high-risk genetic mutations. Because the risk associated with rs11571833 is small, it is not typically used to change standard screening recommendations. You should discuss your specific risk profile with a healthcare provider.
Where can I find more information about my BRCA2 status?
If you have questions about your genetic results, you should consult a certified genetic counselor. They can provide context based on your personal and family medical history and explain what the results mean for you.
Sources & further reading
Educational information only, last refreshed 9/21/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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This variant is a clinically significant allele in the BRCA2 gene associated with hereditary breast and ovarian cancer syndrome.
This variant (p.Lys3326Ter) is classified as a benign polymorphism and is not considered a primary driver of hereditary breast and ovarian cancer susceptibility.
A pathogenic variant in BRCA2 associated with hereditary breast and ovarian cancer syndrome.
A pathogenic variant in the BRCA2 gene associated with hereditary breast and ovarian cancer.
A rare pathogenic variant in the BRCA2 gene associated with hereditary breast and ovarian cancer syndrome.
Also known as Lys3326Ter (K3326X), this truncating variant in the C-terminus of BRCA2 confers moderate increased susceptibility to breast, ovarian, and lung cancers.