RNF212 is a SUMO E3 ligase that plays critical roles in meiotic crossover formation and oocyte quality control. During meiosis, RNF212 localizes to recombination sites where it stabilizes pro-crossover factors including the MutSγ complex proteins MSH4 and MSH5, and TEX11 1. RNF212 acts as a limiting factor for crossover designation and works antagonistically with the ubiquitin ligase HEI10 to regulate the crossover/non-crossover decision at recombination sites 1. RNF212 functions in partnership with its paralog RNF212B, with both proteins essential for crossover maturation through their distinct E3 ligase activities 2. Beyond crossover formation, RNF212 mediates oocyte quality control by sensitizing oocytes to DNA double-strand break-induced apoptosis during chromosome 4, enabling elimination of defective gametes 3. Mutations in RNF212 cause male infertility with meiotic arrest, with genetic variants showing association with azoospermia in human populations 45. The protein also shows associations with maternal meiotic aneuploidy risk through effects on crossover recombination 6. RNF212's dual function in crossover formation and quality control makes it essential for reproductive success in both sexes.