XRCC2 is a RAD51 paralog that functions as a critical component of the BCDX2 complex (RAD51B-RAD51C-RAD51D-XRCC2), essential for homologous recombination-mediated repair of double-stranded DNA breaks 1. The BCDX2 complex orchestrates RAD51 nucleoprotein filament assembly on single-stranded DNA, operating downstream of BRCA2 recruitment and upstream of RAD51 engagement 1. XRCC2 binds Holliday junctions and replication fork structures, facilitating replication fork protection and chr7 stability [UniProt]. Mutations in XRCC2 are associated with Fanconi anemia complementation group U and primary ovarian insufficiency 2, reflecting its critical roles in meiosis and DNA repair pathways. XRCC2 variants are implicated in pancreatic cancer susceptibility within populations carrying homologous recombination gene mutations 3. However, truncating XRCC2 variants show substantially lower breast cancer risk compared to other DNA repair genes like PALB2 or ATM, with one study excluding substantial breast cancer predisposition from XRCC2 truncating variants 4. The protein's function depends on coupled ATPase activities within the BCDX2 complex and structural maintenance of protein-protein interactions critical for RAD51 filament dynamics.