BRCA2

BRCA2
ProteinBoxBot at English Wikipedia · Public domain · source
Name	BRCA2
Chromosome	13q13.1
Locus	13q13.1
Protein	BRCA2 protein
Aliases	FANCD1

BRCA2 BRCA2 is a human tumor suppressor gene encoding a protein essential for homologous recombination repair of DNA double-strand breaks. Originally identified in linkage studies of familial breast and ovarian cancer pedigrees, BRCA2 has been studied in clinical genomics, cancer epidemiology, and molecular biology research communities. Its dysfunction is associated with increased risk for several cancers and has driven advances in targeted therapies and genetic counseling in institutions worldwide.

Function and Molecular Mechanism

BRCA2 participates directly in homologous recombination by mediating the loading of RAD51 onto single-stranded DNA at resected double-strand breaks, coordinating with PALB2, DSS1, and the MRN complex to ensure high-fidelity repair. Studies using purified components, cryo-EM, and X-ray crystallography conducted by groups at institutions such as the Wellcome Trust Centre, Cold Spring Harbor Laboratory, and the Max Planck Institute have detailed interactions with RAD51, RPA, and replication fork protection factors that stabilize stalled forks alongside BRCA1 and FANCD2. BRCA2 contains BRC repeats and a C-terminal DNA-binding domain that bind RAD51 and single-stranded DNA, respectively, with regulatory phosphorylation events controlled by kinases including ATM, ATR, CDK1, and CHEK2 influencing cell-cycle–dependent activity as shown in work from Johns Hopkins, Harvard Medical School, and the University of Cambridge. In mitosis and meiosis, BRCA2 collaborates with DMC1, MRE11, and EXO1 to preserve genome integrity, and its loss leads to chromosomal instability phenotypes observed in studies from the Sanger Institute and EMBL.

Genetics and Mutations

Germline pathogenic variants in BRCA2—nonsense, frameshift, large rearrangements, and specific missense changes—were mapped initially through linkage analysis by research teams at the Imperial Cancer Research Fund and Myriad Genetics. Founder mutations in populations studied by the International Agency for Research on Cancer, Memorial Sloan Kettering Cancer Center, and the University of Toronto illustrate geographic clustering, including variants characterized in Ashkenazi, Icelandic, Norwegian, and Japanese cohorts. Somatic alterations and loss of heterozygosity are frequent in tumors profiled by The Cancer Genome Atlas, Broad Institute, and Genentech, demonstrating biallelic inactivation with cooperating lesions in TP53, PTEN, and KRAS. Variant interpretation frameworks adopted by the American College of Medical Genetics and Genomics, ClinGen, and ENIGMA combine functional assays from laboratories such as Cold Spring Harbor and Baylor College of Medicine with population data from gnomAD and ExAC to classify variants of uncertain significance versus pathogenic alleles.

Clinical Significance and Cancer Risk

Heritable BRCA2 pathogenic variants confer elevated lifetime risks for breast and ovarian cancer documented in cohort studies led by institutions like the UK Biobank, Surveillance, Epidemiology, and End Results Program, and the International BRCA Consortium. Associations extend to male breast cancer, pancreatic cancer, prostate cancer—investigated by groups at Dana-Farber, Mount Sinai, and MD Anderson—and to increased sensitivity to environmental exposures examined by the World Health Organization and International Agency for Research on Cancer. Penetrance estimates derived from prospective registries at the National Cancer Institute and deCODE genetics guide risk-reduction strategies used by oncology centers across Europe and North America, while epidemiologic meta-analyses published in journals overseen by editors at Nature, Lancet, and the New England Journal of Medicine synthesize data on modifier loci such as CHEK2, PALB2, and FANCA.

Diagnosis and Genetic Testing

Genetic testing for BRCA2 uses sequencing and copy-number assays performed in clinical laboratories at Invitae, Myriad Genetics, and Ambry Genetics, guided by testing criteria from the National Comprehensive Cancer Network, American Society of Clinical Oncology, and European Society for Medical Oncology. Multigene panels including BRCA2, BRCA1, PALB2, ATM, and CHEK2 are implemented in diagnostic workflows at Mayo Clinic, Cleveland Clinic, and Karolinska Institutet, with confirmatory analyses using multiplex ligation-dependent probe amplification or comparative genomic hybridization. Pre-test and post-test counseling protocols developed by the Genetic Counseling community, including professional societies like NSGC and BBSTRS, address variant interpretation, cascade testing of relatives, and reporting standards harmonized through ClinVar submissions coordinated by the National Center for Biotechnology Information.

Management and Treatment Implications

Identification of BRCA2 pathogenic variants informs risk-reduction strategies such as prophylactic mastectomy and salpingo-oophorectomy recommended by specialist panels at the Royal Marsden, Memorial Sloan Kettering, and St. George’s Hospital, and chemoprevention trials coordinated by the Breast Cancer Trialists’ Collaborative Group. Tumor BRCA2 deficiency predicts sensitivity to platinum-based chemotherapy regimens used at major cancer centers and to poly(ADP-ribose) polymerase (PARP) inhibitors developed by companies including AstraZeneca, Pfizer, and Clovis Oncology; pivotal trials such as those published by EMBRACA, SOLO, and PROfound influenced regulatory decisions by the FDA and EMA. Resistance mechanisms involving reversion mutations, replication fork stabilization, and efflux transporter upregulation have been characterized by research consortia at Institut Curie and the Francis Crick Institute, informing combination strategies with immune checkpoint inhibitors tested in cooperative groups like SWOG and EORTC.

Evolutionary Conservation and Model Organisms

BRCA2 orthologs are conserved across eukaryotes with functional studies in Saccharomyces cerevisiae (Rad52 pathway context), Schizosaccharomyces pombe, Drosophila melanogaster, Mus musculus, and Danio rerio elucidating conserved roles in recombination and development; landmark mouse knockout models generated at the National Institutes of Health and research institutions such as Jackson Laboratory recapitulate tumor predisposition and embryonic phenotypes. Comparative genomics efforts at the Broad Institute and EBI reveal conserved BRC repeat architecture, while functional complementation assays in yeast and chicken DT40 cells conducted at the Francis Crick Institute and Kyoto University help classify human variants. Evolutionary analyses published by groups at Harvard and Stanford place BRCA2 within broader studies of genome maintenance genes across Metazoa and Viridiplantae.

Category:Human genes