What you carry at this position in your DNA and what research says about it.
Cancer Risk: 10/10 evidence, 25 publications.
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Sample genotype (not yours): A/A
Typical Cancer Risk
The common version of this gene does not elevate the risk for breast, lung, or other cancers. This genetic profile represents the baseline risk found in the general population.
What this genotype means: Typical baseline risk for breast cancer; Typical baseline risk for lung cancer; Produces fully functional BRCA2 protein.
Sample genotype (not yours): A/T
Slightly Increased Cancer Risk
One copy of the T allele is associated with a modest increase in the risk of developing breast, lung, and certain other cancers. This variant acts as a low-penetrance risk factor, meaning it slightly nudges risk upward without causing high-risk hereditary cancer syndrome.
What this genotype means: Modestly increased risk of breast cancer; Slightly elevated risk of lung cancer; Slightly higher susceptibility to multiple myeloma.
Sample genotype (not yours): T/T
Increased Cancer Risk
Two copies of the T allele are associated with an elevated risk of breast, lung, and other cancers. This rare genetic profile does not cause severe hereditary cancer syndrome, but it acts as a low-penetrance risk factor.
What this genotype means: Elevated risk of breast cancer; Elevated risk of lung cancer; Slightly higher risk of upper aerodigestive tract cancers.
Gene function and biological role
Gene Function: BRCA2 is a tumor suppressor gene that plays a critical role in maintaining genomic stability by repairing damaged DNA [1]. It specifically helps repair double-strand DNA breaks through homologous recombination [1]. When BRCA2 is fully functional, it prevents cells from growing and dividing too rapidly or in an uncontrolled way. However, certain inherited mutations in BRCA2 can impair this repair process, leading to an accumulation of genetic errors and a significantly higher risk of developing cancers, particularly breast and ovarian cancers [2].
Variant Impact: The rs11571833 variant, also known as p.Lys3326Ter or K3326X, is a stop-gain mutation located in the final exon of the BRCA2 gene [3]. This genetic change introduces a premature stop signal, resulting in a protein that is missing its last 93 amino acids [4]. Because this truncation occurs at the very end of the protein, the cell does not destroy the transcript, and the resulting protein retains most of its normal DNA repair capabilities [3]. Consequently, clinical databases classify this variant as benign for high-penetrance hereditary breast and ovarian cancer syndromes [5]. However, large-scale genetic studies have revealed that it acts as a low-penetrance risk factor, modestly increasing the susceptibility to several types of cancer [6].
Key Insight: Unlike most BRCA2 stop mutations, this variant does not cause high-risk hereditary breast and ovarian cancer syndrome, but instead acts as a mild risk factor across multiple cancers.
Location: BRCA2. Chromosome 13 · 13q13.1 · 32.4 Mb
Estimated prevalence by population
Global 98.8%; European 98.3%; African 99.8%; East Asian 100.0%; South Asian 98.6%; Americas 99.0%; Ashkenazi 98.9%; Finnish 97.9%; Middle Eastern 98.6%; Amish 93.1%.
Estimated AA genotype frequency.
Global 1.2%; European 1.7%; African 0.2%; East Asian 0.0%; South Asian 1.4%; Americas 1.0%; Ashkenazi 1.1%; Finnish 2.1%; Middle Eastern 1.4%; Amish 6.8%.
Estimated AT genotype frequency.
Global < 0.1%; European < 0.1%; African < 0.1%; East Asian 0.0%; South Asian < 0.1%; Americas < 0.1%; Ashkenazi < 0.1%; Finnish < 0.1%; Middle Eastern < 0.1%; Amish 0.1%.
Estimated TT genotype frequency.
Showing effects for A/A genotype
Cancer & Oncology
Breast Cancer
Breast Cancer. Evidence: 9/10. Source: PMID 23535729. Typical Risk.
Lung Cancer
Lung Cancer. Evidence: 10/10. Source: PMID 24880342. Typical Risk.
Blood Cancers
Multiple Myeloma. Evidence: 7/10. Source: PMID 39103364. Typical Risk.
Skin Cancer
Squamous Cell Carcinoma. Evidence: 9/10. Source: PMID 32041948. Typical Risk.
Showing effects for A/T genotype
Breast Cancer. Evidence: 9/10. Source: PMID 23535729. ~1.3x Higher Risk.
Lung Cancer. Evidence: 10/10. Source: PMID 24880342. ~1.6x Higher Risk.
Multiple Myeloma. Evidence: 7/10. Source: PMID 39103364. ~1.6x Higher Risk.
Squamous Cell Carcinoma. Evidence: 9/10. Source: PMID 32041948. Increased Risk.
Showing effects for T/T genotype
Breast Cancer. Evidence: 9/10. Source: PMID 23535729. Increased Risk.
Lung Cancer. Evidence: 10/10. Source: PMID 24880342. Increased Risk.
Multiple Myeloma. Evidence: 7/10. Source: PMID 39103364. Increased Risk.
What this genotype means for the people who carry it
Sample genotype: AA (Homozygous)
Two copies of the common A allele mean the K3326X truncation variant is absent. Large-scale genome-wide association studies show that individuals with this baseline genotype have typical risks for breast cancer [1] and lung cancer [2]. Because you lack the risk-increasing T allele, your genetic predisposition to these malignancies is not elevated by this specific locus. Your BRCA2 gene produces a full-length, fully functional protein that successfully participates in DNA repair pathways [3]. Clinical databases like ClinVar confirm that this common genotype represents a normal, non-pathogenic baseline [4].
Typical baseline risk for breast cancer; Typical baseline risk for lung cancer; Produces fully functional BRCA2 protein.
Sample genotype: AT (Heterozygous)
A single copy of the T allele introduces a premature stop codon near the very end of the BRCA2 gene, known as the K3326X variant [1]. While this change does not cause high-penetrance hereditary breast and ovarian cancer syndrome [2], it is recognized as a low-penetrance susceptibility factor. Large genetic studies have linked this genotype to a modest increase in breast cancer risk, with an odds ratio of approximately 1.33 [3]. It is also associated with a slightly higher risk of lung cancer, particularly squamous cell and small cell subtypes [4]. Other research suggests small increases in susceptibility to multiple myeloma and skin squamous cell carcinoma [5]. Because the protein retains most of its function, the risk increase is mild compared to classic pathogenic BRCA2 mutations.
Modestly increased risk of breast cancer; Slightly elevated risk of lung cancer; Slightly higher susceptibility to multiple myeloma.
Sample genotype: TT (Homozygous)
Both copies of the BRCA2 gene carry the K3326X truncation variant in this rare genetic profile [1]. This genotype is exceptionally rare in most populations, occurring in less than one in ten thousand individuals. Although homozygous carriers of this variant reach old age and do not develop severe childhood syndromes like Fanconi anemia [2], they face an elevated risk of several adult cancers. Studies show that the T allele increases susceptibility to breast cancer [3] and lung cancer [4]. The risk is particularly notable for squamous cell lung cancer and upper aerodigestive tract cancers [5]. Because this variant only mildly impairs BRCA2 function, the overall risk is still much lower than that of classic high-penetrance BRCA2 mutations.
Elevated risk of breast cancer; Elevated risk of lung cancer; Slightly higher risk of upper aerodigestive tract cancers.
Variants with shared genetic architecture
rs11571818 · BRCA2 Gene · Chr 13 · Lung Cancer Risk
rs4942486 · BRCA2 Gene · Chr 13 · Cholesterol Levels
rs80359365 · BRCA2 Gene · Chr 13 · Hereditary Cancer Risk
BRCA2: one small step for DNA repair, one giant protein purified.
A polymorphic stop codon in BRCA2.
Functional evaluation and cancer risk assessment of BRCA2 unclassified variants.
Association analysis identifies 65 new breast cancer risk loci.
Deciphering the genetics and mechanisms of predisposition to multiple myeloma.
A rare truncating BRCA2 variant and genetic susceptibility to upper aerodigestive tract cancer.
Content updated August 2026.
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