MCM8 is a DNA helicase component of the MCM8-MCM9 complex essential for homologous recombination repair of double-stranded breaks and interstrand crosslinks 1. The complex functions as a 3'-5' DNA helicase with ssDNA-stimulated ATPase activity 2 and promotes DNA resection by recruiting and activating the MRE11-RAD50-NBN complex to damage sites 3. MCM8 indirectly regulates RAD51 localization to DNA lesions 1 and facilitates mitochondrial DNA recombination 4. The complex is dispensable for S-phase DNA replication but plays critical roles in gametogenesis through homologous recombination regulation 1. MCM8 mutations are the predominant genetic cause of primary ovarian insufficiency/premature ovarian failure 567, where it recruits R-loop-resolving helicases DDX5 and DHX9 to prevent genome instability in primordial germ cells 8. MCM8 deficiency impairs germ cell proliferation and fertility 8. In non-obstructive azoospermia, MCM8 mutations correlate with failed sperm retrieval 9. Beyond reproduction, MCM8 regulates mitophagy through LC3 recruitment, protecting vascular health in Kawasaki disease models 10, and is upregulated in colorectal cancer where it promotes tumor progression 11.