RAG2 and immunodeficiency disease: We have shown before that mutant Kit combined with immunodeficiency mediated by null mutations in the recombination activating gene 2 (Rag2) and interleukin 2 receptor gamma chain gene (Il2rgc) facilitates near-complete engraftment of murine syngeneic but also histoincompatible allogeneic donor mouse HSCs in the absence of any further conditioning therapy (Waskow et al., 2009).