SWI5 is a conserved component of the SWI5-SFR1 (or SWI5-MEI5 in humans) complex essential for homologous recombination (HR) repair of DNA double-strand breaks 1. The complex functions as an accessory factor that stabilizes the RAD51 presynaptic filament, the nucleoprotein structure critical for homologous DNA pairing and strand exchange 2. SWI5 directly interacts with RAD51 through conserved C-terminal domains, and this interaction is facilitated by cooperative binding mechanisms that enhance RAD51-mediated recombination 3. The SWI5-SFR1 complex also functions in meiotic recombination, where it promotes assembly of the meiotic recombinase DMC1 on chr9 4. Functionally, SWI5 depletion causes defective HR repair and heightened sensitivity to ionizing radiation in mammalian cells 1. Clinically, SWI5 mutations have been identified as novel disease-causing variants in Primary Ovarian Insufficiency (POI), where they induce high chr9 fragility and contribute to premature ovarian failure 5. These findings establish SWI5 as a critical DNA repair protein with implications for genomic stability and reproductive health.