Non human animals and methods and compositions for making and using the same are provided wherein said non human animals comprise a humanization of an endogenous cluster of differentiation (CD) gene in particular a humanization of a CD47 gene. Said non human animals may be described in some embodiments as having a genetic modification to an endogenous CD47 gene so that said non human animals express a CD47 polypeptide that includes a human portion and a non human portion (e.g. a murine portion).