- Pavel-Dinu, Mara;
- Wiebking, Volker;
- Dejene, Beruh;
- Srifa, Waracharee;
- Mantri, Sruthi;
- Nicolas, Carmencita;
- Lee, Ciaran;
- Bao, Gang;
- Kildebeck, Eric;
- Punjya, Niraj;
- Sindhu, Camille;
- Saxena, Nivedita;
- DeRavin, Suk;
- Malech, Harry;
- Roncarolo, Maria;
- Weinberg, Kenneth;
- Porteus, Matthew;
- Inlay, Matthew
Gene correction in human long-term hematopoietic stem cells (LT-HSCs) could be an effective therapy for monogenic diseases of the blood and immune system. Here we describe an approach for X-linked sSevere cCombined iImmunodeficiency (SCID-X1) using targeted integration of a cDNA into the endogenous start codon to functionally correct disease-causing mutations throughout the gene. Using a CRISPR-Cas9/AAV6 based strategy, we achieve up to 20% targeted integration frequencies in LT-HSCs. As measures of the lack of toxicity we observe no evidence of abnormal hematopoiesis following transplantation and no evidence of off-target mutations using a high-fidelity Cas9 as a ribonucleoprotein complex. We achieve high levels of targeting frequencies (median 45%) in CD34+ HSPCs from six SCID-X1 patients and demonstrate rescue of lymphopoietic defect in a patient derived HSPC population in vitro and in vivo. In sum, our study provides specificity, toxicity and efficacy data supportive of clinical development of genome editing to treat SCID-Xl.