protein coding gene repro22 Mad2l2 + O MGI:1919140 http://identifiers.org/mgd/MGI:1919140 Gene MAD2 mitotic arrest deficient-like 2 G1-453-4 G1-453-4|MAD2B|REV7|2310033C13Rik|repro22 REV7 2310033C13Rik genetic mapping MAD2B