genetic mapping dominant brown Dbr Gene MGI:2153040 http://identifiers.org/mgd/MGI:2153040 Aim1 Dbr|Aim1|dominant brown|Oca4|bls|blanc-sale|Aim-1|Matp Matp Slc45a2 solute carrier family 45, member 2 bls blanc-sale O Aim-1 + Oca4 protein coding gene