Patent ID: 8642835

Claim:
A genetically modified mouse whose genome comprises: (a) ectopic placement of an ADAM6 gene; and (b) a human immunoglobulin heavy chain variable region locus comprising an insertion of one or more human V H gene segments, one or more human D H gene segments, and one or more human J H gene segments into the endogenous mouse heavy chain locus, wherein the human V H , D H and J H gene segments are operably linked to a heavy chain constant region gene; so that the mouse is characterized in that: (i) it is fertile; and (ii) when it is immunized with an antigen, it generates antibodies comprising heavy chain variable domains encoded by the one or more human V H , one or more human D H , and one or more human J H gene segments, linked to heavy chain constant domains encoded by the heavy chain constant region gene, wherein the antibodies show specific binding to the antigen.