RAG2 and immune system disorder: RAG1 or RAG2 defect causes typical T-B-NK+ SCID, Omenn syndrome, and also some rare peculiar forms: immunodeficiency with early onset of multivisceral and recurrent CMV infection, autoimmune cytopenia, restricted T cell repertoire with TCRαβ+ lymphopenia and markedly expanded TCRγδ+ T cells; immunodeficiency with extensive granulomatous disease involving the skin, mucous membranes and internal organs, and EBV-lymphoma; etc. [36,63]