X linked severe combined immunodeficiency (X-SCID), is a recessive disease caused by mutations to the gene IL2Rγ and is characterized by a non-functional immune system. We have designed a method for functionally correcting patient hematopoietic stem cells, at the IL2Rγ locus, by creating a double strand break at the first exon of IL2Rγ and delivering a repair donor using an AAV6 vector. The repair donor contains a functional cDNA of IL2Rγ and a selectable marker, truncated nerve growth factor receptor (tNGFR). Optimizing our genome editing strategy in K562 cells a myelogenous cell line. We have found we are able to target upwards of 40% of K562 cells with our donor and enrich for cells expressing tNGFR four fold. Using our genome editing strategy in hematopoietic stem and progenitor cells (HSPC’s) we have found we can target a population of CD34+ cells at the IL2RΓ locus with our donor and enrich for targeted cells 90 fold. We have shown that we can target 8% of CD34+ cells at the IL2RΓ locus with a donor containing only a reporter gene however our rates of targeting with our clinical donor for the treatment of X-SCID are below 2%.