We believe that the CRISPR-Cas9/rAAV6-based CDS replacement strategy for a proof-of-concept gene therapy, which is site-specific and in a clinical setting would use a patient’s own cells, can alleviate a number of current barriers to treatment for not only RAG2-SCID but other monogenic diseases of the blood and immune system as well. Here, RAG2 is linked to glycogen storage disease VI.