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BRCA2
BRCA2 DNA repair associated
BRCA2 encodes a tumour suppressor protein critical for repairing DNA double-strand breaks and maintaining genomic stability. The BRCA2 gene produces a protein that coordinates the cellular response to DNA damage, particularly double-strand breaks.
BRCA2 is located on the long (q) arm of chromosome 13, at band 13q13.1. Arm ratio per GRCh38 - banding schematic.
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Overview
BRCA2 (BRCA2 DNA repair associated) is located on chromosome 13 and encodes a large protein of 3,418 amino acids that serves as a central mediator of homologous recombination repair. This gene belongs to a class of tumour suppressors whose primary function is to preserve the integrity of genetic information by coordinating the repair of DNA double-strand breaks, among the most harmful forms of DNA damage a cell can experience. When both copies of BRCA2 carry pathogenic variants, cells lose a critical safeguard against genomic instability, allowing mutations to accumulate and potentially leading to malignant transformation.
Inherited pathogenic variants in BRCA2 follow an autosomal dominant pattern, meaning a single altered copy can substantially elevate cancer risk over a lifetime. Individuals who carry such variants face increased susceptibility to breast cancer in both women and men, ovarian cancer, prostate cancer, pancreatic cancer, and other malignancies. The gene is included in the American College of Medical Genetics and Genomics (ACMG) Secondary Findings list as a Tier 1 actionable gene, reflecting the availability of evidence-based surveillance and risk-reduction strategies for carriers.
BRCA2-related cancer predisposition has been recognised across diverse populations, with certain pathogenic variants occurring at higher frequencies in specific ancestral groups, including Ashkenazi Jewish, Icelandic, and other European populations. Understanding the gene's function and variant landscape is essential for interpreting genetic test results, guiding personalised screening protocols, and informing reproductive planning for families affected by hereditary cancer syndromes.
What the gene does
The BRCA2 protein operates primarily within the cell nucleus, where it facilitates the repair of DNA double-strand breaks through a process called homologous recombination. This high-fidelity repair pathway uses an intact sister chromatid as a template to restore the original DNA sequence, preventing the loss or rearrangement of genetic information that could otherwise drive malignant transformation. BRCA2 achieves this by recruiting and regulating RAD51, a recombinase that catalyses strand invasion and homology search during repair.
BRCA2 contains multiple BRC repeats, short sequence motifs distributed across the central portion of the protein that bind directly to RAD51. These repeats control RAD51 nucleoprotein filament assembly on single-stranded DNA at sites of damage, ensuring that repair proceeds accurately and efficiently. The protein also interacts with PALB2 (Partner and Localiser of BRCA2) through its N-terminal region, an interaction essential for recruiting BRCA2 to sites of DNA damage and stabilising the BRCA1-PALB2-BRCA2 complex that orchestrates the homologous recombination response.
Beyond its canonical role in double-strand break repair, research suggests BRCA2 contributes to the stabilisation of stalled replication forks, protecting nascent DNA strands from degradation when DNA synthesis encounters obstacles such as DNA lesions or secondary structures. The protein has also been implicated in the regulation of cytokinesis, the final stage of cell division, although the molecular details of this function remain under investigation. Some studies indicate that BRCA2 may interact with DNA polymerase eta (POLH) to support translesion synthesis, a specialised DNA replication process that allows cells to bypass certain types of DNA damage.
The maintenance of genomic stability by BRCA2 is tissue-specific in its consequences: loss of function in rapidly proliferating epithelial tissues such as breast, ovary, and prostate appears to confer particularly high cancer risk, possibly because these tissues experience frequent cell division and DNA replication stress. Cells lacking functional BRCA2 accumulate chromosomal aberrations, including deletions, translocations, and aneuploidy, creating a mutational landscape that can promote tumour development. BRCA2 deficiency also renders cells sensitive to agents that cause DNA crosslinks or inhibit poly(ADP-ribose) polymerase (PARP), a characteristic exploited therapeutically in PARP inhibitor treatment for BRCA2-associated cancers.
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Chromosome location
BRCA2 is located on the long arm of chromosome 13 at cytogenetic band 13q13.1, a region that spans approximately 84 kilobases of genomic DNA. The gene comprises 27 exons, with exon 11 being exceptionally large and encoding much of the central portion of the protein, including the majority of the BRC repeats critical for RAD51 interaction. This genomic architecture makes exon 11 a frequent site of pathogenic variants, although alterations occur throughout the gene.
The 13q13.1 region is relatively gene-dense, with BRCA2 situated among other genes involved in cellular regulation and signalling. The chromosomal context has implications for structural variation: large deletions or duplications encompassing BRCA2 exons can arise through non-allelic homologous recombination or other mechanisms, and such copy-number variants are detected through specialised laboratory methods in clinical testing. The gene's size and complexity present technical challenges for sequencing and variant interpretation, necessitating comprehensive genomic approaches to identify the full spectrum of pathogenic alterations.
Protein structure
The BRCA2 protein is organised into several functionally distinct regions that coordinate its role in DNA repair and genomic maintenance. The N-terminal region (amino acids 1 to 40) mediates the Interaction with PALB2, a critical partnership that localises BRCA2 to DNA damage sites and integrates it into the broader BRCA1-PALB2-BRCA2 repair complex. Adjacent to this functional domain are two Disordered regions (amino acids 37 to 68 and 358 to 381), which may provide structural flexibility for protein-protein interactions and regulatory modifications.
The central portion of BRCA2 contains the Interaction with RAD51 region (amino acids 1,003 to 2,082), within which eight BRC repeats are embedded. These repeats include BRCA2 1 (amino acids 1,002 to 1,036), BRCA2 2 (amino acids 1,212 to 1,246), BRCA2 3 (amino acids 1,421 to 1,455), BRCA2 4 (amino acids 1,517 to 1,551), BRCA2 5 (amino acids 1,664 to 1,698), BRCA2 6 (amino acids 1,837 to 1,871), BRCA2 7 (amino acids 1,971 to 2,005), and BRCA2 8 (amino acids 2,051 to 2,085). Each repeat binds RAD51 independently, enabling BRCA2 to regulate the assembly and dynamics of RAD51 filaments on damaged DNA with exquisite precision.
Overlapping with the RAD51-interaction region is the Interaction with NPM1 domain (amino acids 639 to 1,000), which may influence nucleolar function or protein stability. The Interaction with POLH region (amino acids 1,338 to 1,781) facilitates cooperation with DNA polymerase eta during translesion synthesis, with a more narrowly defined segment Required for stimulation of POLH DNA polymerisation activity (amino acids 1,410 to 1,595) being essential for this function. Together, these structural elements enable BRCA2 to serve as a molecular scaffold, bringing together repair enzymes and regulatory factors at sites of DNA damage to ensure faithful genomic maintenance.
Key variants
The variant landscape of BRCA2 is extraordinarily diverse, encompassing single-nucleotide variants, small insertions and deletions, splice-site alterations, and large genomic rearrangements affecting one or more exons. Pathogenic variants are distributed across the entire coding sequence, although certain regions, particularly the large exon 11, harbour a disproportionate number of disease-causing alterations. Frameshift and nonsense variants that introduce premature stop codons typically result in loss of protein function through nonsense-mediated decay or production of truncated, nonfunctional polypeptides.
Certain founder mutations occur at elevated frequencies in specific populations due to historical genetic bottlenecks. For example, the 6174delT variant is observed in approximately one in 40 individuals of Ashkenazi Jewish ancestry, while the 999del5 variant has been identified as a founder mutation in Icelandic populations. These recurrent variants enable targeted screening strategies in high-risk communities, although comprehensive sequencing remains the standard of care to detect the full spectrum of rare and private variants.
Variant interpretation in BRCA2 follows international guidelines established by the American College of Medical Genetics and Genomics and the Association for Molecular Pathology. Classification depends on multiple lines of evidence, including the predicted effect on protein function, segregation data from affected families, case-control studies, and functional assays. Variants of uncertain significance represent a substantial proportion of findings in clinical testing, and their classification may be refined over time as additional data accumulate. Large deletions and duplications, detected through methods such as multiplex ligation-dependent probe amplification or next-generation sequencing with copy-number analysis, constitute a meaningful fraction of pathogenic alterations and must be considered in comprehensive genetic evaluation.
Sample of pathogenic variants
10 pathogenic / likely-pathogenic variants from ClinVar, ranked by review status (expert-panel-reviewed first). This is a sample; recurrent founder variants in a specific population may not appear here - see the full ClinVar listing via the link above.
| Variant (HGVS) | Protein change | Classification | Evidence | Associated condition |
|---|---|---|---|---|
g.32316508_32316510delinsATCGATCGAT | - | Pathogenic | ★★★☆ | Breast-ovarian cancer, familial, susceptibility to, 2 |
g.32331002_32331007delinsAAACAAT | - | Pathogenic | ★★★☆ | Breast-ovarian cancer, familial, susceptibility to, 2 |
g.32332376_32332378delinsTT | - | Pathogenic | ★★★☆ | Hereditary breast ovarian cancer syndrome |
g.32332703delinsTTT | - | Pathogenic | ★★★☆ | Breast-ovarian cancer, familial, susceptibility to, 2 |
g.32332710_32332720delinsACAT | - | Pathogenic | ★★★☆ | Breast-ovarian cancer, familial, susceptibility to, 2 |
g.32332927_32332929delinsTTCC | - | Pathogenic | ★★★☆ | Breast-ovarian cancer, familial, susceptibility to, 2 |
g.32333289_32333290delinsG | - | Pathogenic | ★★★☆ | Breast-ovarian cancer, familial, susceptibility to, 2 |
g.32337455dup | - | Pathogenic | ★★★☆ | Breast-ovarian cancer, familial, susceptibility to, 2 |
g.32337505_32337508delinsATTTT | - | Pathogenic | ★★★☆ | Breast-ovarian cancer, familial, susceptibility to, 2 |
g.32337512_32337523delinsAG | - | Pathogenic | ★★★☆ | Breast-ovarian cancer, familial, susceptibility to, 2 |
Evidence stars indicate ClinVar review status. Individual variant interpretation should always be performed by a qualified clinical laboratory - many variants remain classified as Variants of Uncertain Significance (VUS) pending more research.
Associated conditions
Pathogenic variants in BRCA2 are principally associated with hereditary breast and ovarian cancer syndrome, an autosomal dominant condition characterised by markedly elevated lifetime risks of breast cancer in both women and men, ovarian cancer, and several other malignancies. Women who inherit a BRCA2 pathogenic variant face lifetime breast cancer risks often exceeding 50 per cent, with ovarian cancer risks in the range of 10 to 25 per cent, compared with population baseline risks of approximately 12 per cent and 1 to 2 per cent, respectively. The age of onset tends to be younger than in sporadic cases, and bilateral breast cancer occurs more frequently.
Men with pathogenic BRCA2 variants experience increased risk of breast cancer, with lifetime estimates around 5 to 10 per cent, as well as elevated risk of prostate cancer, which may present at earlier ages and with more aggressive features. BRCA2-associated prostate cancer is recognised as a distinct clinical entity under the designation hereditary prostate cancer. Additional malignancies observed at increased frequency include pancreatic cancer, melanoma, and possibly gastric and bile duct cancers, although risk estimates for these remain less precisely defined.
Biallelic pathogenic variants in BRCA2, where both gene copies are altered, result in Fanconi anaemia complementation group D1, a rare recessive disorder characterised by bone marrow failure, congenital anomalies, and extreme predisposition to childhood malignancies. This condition is phenotypically distinct from the monoallelic cancer predisposition syndromes and reflects the essential role of BRCA2 in normal haematopoietic development and DNA repair. Patau syndrome, a chromosomal disorder, is listed among associated conditions due to chromosomal context but is not caused by BRCA2 variants per se.
Inheritance pattern
Conditions caused by pathogenic BRCA2 variants typically follow autosomal dominant inheritance.
Each child has a 50% chance of inheriting the pathogenic variant, regardless of sex.
UK clinical status
BRCA2 holds a prominent position in UK clinical genomics, reflected in its inclusion across more than 30 NHS Genomic Medicine Service gene panels with green (high-evidence) classification. The gene features in Adult solid tumours cancer susceptibility and Adult solid tumours for rare disease panels, underscoring its relevance to cancer predisposition assessment in adults. It is a core component of Familial breast cancer, Inherited breast cancer and ovarian cancer, Inherited ovarian cancer (without breast cancer), and Familial prostate cancer panels, which guide testing for individuals with personal or family histories suggestive of hereditary cancer syndromes.
BRCA2 appears on the Inherited pancreatic cancer panel (R367), Inherited prostate cancer panel (R430), and NICE approved PARP inhibitor treatment panel (R444), the latter reflecting the therapeutic implications of BRCA2 status for patients with certain cancers who may benefit from PARP inhibitor therapy. The gene is also listed on Additional findings health related, Additional findings health related - adult specific, and Additional findings health related - CNV analysis adult specific panels, indicating that BRCA2 findings may be reported as secondary or incidental results when whole-genome or whole-exome sequencing is performed for unrelated indications.
Beyond cancer predisposition, BRCA2 is included in panels addressing developmental and haematological phenotypes, such as Confirmed Fanconi anaemia or Bloom syndrome (R229), Cytopenias and congenital anaemias, Fetal anomalies (R21), Limb disorders, Radial dysplasia, and Severe microcephaly (R88), reflecting the gene's role in biallelic disease presentations. This broad panel representation ensures that BRCA2 variants are considered across diverse clinical contexts within the NHS, from cancer risk assessment to prenatal diagnosis and evaluation of congenital anomalies.
Sources: NHS GMS PanelApp · Genomics England PanelApp · NHS National Genomic Test Directory
Diet & lifestyle considerations
Research into lifestyle factors and cancer risk in BRCA2 variant carriers suggests that certain modifiable behaviours may influence cancer outcomes, although evidence remains observational and should not be interpreted as personalised medical advice. Some studies indicate that maintaining a healthy body weight and engaging in regular physical activity are associated with modestly reduced breast cancer risk in the general population, and limited data suggest these associations may extend to carriers of BRCA pathogenic variants, though the magnitude of benefit is uncertain.
Alcohol consumption has been consistently linked to increased breast cancer risk in population studies, and some evidence suggests that limiting alcohol intake may be prudent for individuals at elevated genetic risk, including those with BRCA2 variants. Observational data on dietary patterns, including adherence to diets rich in vegetables, fruits, and whole grains, have yielded mixed results, and no specific dietary intervention has been proven to substantially reduce cancer risk in carriers. Smoking is associated with increased risk of several cancers, including pancreatic cancer, which occurs at elevated rates in BRCA2 carriers, and smoking cessation is generally advised for overall health.
Screening and risk-reduction strategies, rather than lifestyle modification alone, remain the cornerstone of cancer prevention in BRCA2 carriers. These include enhanced breast surveillance with magnetic resonance imaging and mammography, risk-reducing mastectomy, risk-reducing salpingo-oophorectomy, and prostate cancer screening protocols tailored to elevated-risk populations. Individuals with pathogenic BRCA2 variants should engage with specialist genetic counselling and clinical services to develop personalised surveillance and management plans. Lifestyle considerations should be discussed within the context of comprehensive care, recognising that genetic predisposition confers risks that lifestyle factors alone cannot eliminate.
Supplement considerations
There is no conclusive evidence that any dietary supplement can prevent cancer or meaningfully reduce cancer risk in individuals carrying pathogenic BRCA2 variants. Some observational studies have explored associations between micronutrient intake and cancer outcomes in the general population, but findings have been inconsistent, and randomised controlled trials of supplementation have largely failed to demonstrate protective effects. Antioxidant supplements such as vitamin E, beta-carotene, and high-dose vitamin C have been investigated in various contexts, with some studies suggesting neutral or even adverse outcomes in certain populations.
Folate and other B vitamins involved in one-carbon metabolism have been studied in relation to DNA repair and cancer risk, given their roles in nucleotide synthesis and methylation. However, evidence linking supplementation to reduced cancer incidence in BRCA variant carriers is lacking, and high-dose folic acid supplementation has raised concerns in some research contexts. Vitamin D has been the subject of interest due to its potential immunomodulatory and antiproliferative effects, but clinical trial data have not established a clear benefit for cancer prevention, and optimal dosing remains undefined.
Omega-3 fatty acids, green tea extracts, and various phytochemicals have been proposed as potential chemopreventive agents based on laboratory and epidemiological research, but rigorous evidence supporting their use in genetically predisposed individuals is absent. Before initiating any supplement regimen, individuals with BRCA2 pathogenic variants should consult with a healthcare provider to discuss potential risks, benefits, and interactions with other medications or treatments. Reliance on supplements should not substitute for evidence-based surveillance, risk-reduction strategies, and medical management, which remain the most effective approaches to reducing cancer morbidity and mortality in this population.
Frequently asked questions
What cancers are associated with BRCA2 pathogenic variants?
Pathogenic variants in BRCA2 are most strongly associated with breast cancer in both women and men, ovarian cancer, prostate cancer, and pancreatic cancer. Elevated risks have also been observed for melanoma and possibly other malignancies, though risk estimates vary and continue to be refined through ongoing research.
How are BRCA2 variants inherited?
BRCA2-associated cancer predisposition follows an autosomal dominant inheritance pattern, meaning a pathogenic variant in one copy of the gene is sufficient to increase cancer risk. Each child of a carrier has a 50 per cent chance of inheriting the variant, regardless of sex.
What is the difference between BRCA1 and BRCA2?
BRCA1 and BRCA2 are both tumour suppressor genes involved in DNA repair, but they encode distinct proteins with different molecular functions and domain structures. BRCA2 primarily mediates RAD51 loading during homologous recombination, while BRCA1 has broader roles in damage sensing and checkpoint control. Both confer elevated cancer risks, though the spectrum and magnitude of risk differ somewhat between the two genes.
Can men carry BRCA2 pathogenic variants?
Yes, men can carry and transmit pathogenic BRCA2 variants. Male carriers face increased risk of breast cancer, prostate cancer, and pancreatic cancer, and they can pass the variant to children of either sex, making family history assessment important for both maternal and paternal lineages.
What does it mean if a BRCA2 variant is classified as uncertain significance?
A variant of uncertain significance (VUS) is a genetic change for which there is insufficient evidence to confidently classify it as pathogenic or benign. VUS findings do not confirm or rule out hereditary cancer predisposition, and clinical management should be based on personal and family history rather than the VUS result. Reclassification may occur as additional data become available.
Are there treatments specifically for BRCA2-associated cancers?
Certain cancers arising in individuals with BRCA2 pathogenic variants may be particularly sensitive to PARP inhibitors, a class of targeted therapy that exploits defective DNA repair in tumour cells. Clinical trials and regulatory approvals have established PARP inhibitors as treatment options for BRCA-associated ovarian, breast, prostate, and pancreatic cancers, often guided by tumour genetic testing and clinical criteria.
References
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- Foulkes WD. BRCA1 and BRCA2 - update and implications on the genetics of breast cancer: a clinical perspective. Clinical genetics. 2014. PMID: 24116874
- Friebel TM, Domchek SM, Rebbeck TR. Modifiers of cancer risk in BRCA1 and BRCA2 mutation carriers: systematic review and meta-analysis. Journal of the National Cancer Institute. 2014. PMID: 24824314
- Shahid T, Soroka J, Kong E. Structure and mechanism of action of the BRCA2 breast cancer tumor suppressor. Nature structural & molecular biology. 2014. PMID: 25282148
- Foulkes WD, Shuen AY. In brief: BRCA1 and BRCA2. The Journal of pathology. 2013. PMID: 23620175
- Kobayashi H, Ohno S, Sasaki Y. Hereditary breast and ovarian cancer susceptibility genes (review). Oncology reports. 2013. PMID: 23779253
- Pennington KP, Swisher EM. Hereditary ovarian cancer: beyond the usual suspects. Gynecologic oncology. 2012. PMID: 22264603
- Shulman LP. Hereditary breast and ovarian cancer (HBOC): clinical features and counseling for BRCA1 and BRCA2, Lynch syndrome, Cowden syndrome, and Li-Fraumeni syndrome. Obstetrics and gynecology clinics of North America. 2010. PMID: 20494261
- Chen S, Parmigiani G. Meta-analysis of BRCA1 and BRCA2 penetrance. Journal of clinical oncology : official journal of the American Society of Clinical Oncology. 2007. PMID: 17416853
- Wagner JE, Tolar J, Levran O. Germline mutations in BRCA2: shared genetic susceptibility to breast cancer, early onset leukemia, and Fanconi anemia. Blood. 2004. PMID: 15070707
- Adam MP, Bick S, Mirzaa GM. BRCA1- and BRCA2-Associated Hereditary Breast and Ovarian Cancer. 1993. PMID: 20301425