One of the reproductive isolation mechanisms that restricts gene exchange and make speciation irreversible is sterility of inter(sub)specific hybrids. In the Prdm9-driven sterility of Mus m. musculus x Mus m. domesticus hybrids a Prdm9-interacting hybrid sterility gene was mapped in the X-linked Hstx2 locus. Here we show that the Mir465 microRNA gene cluster is the predicted Hstx2 hybrid sterility factor involved in Prdm9 interaction.