CCR5 and Scheie syndrome: The CRISPR/Cas9 system was targeted to the human CCR5 locus in hematopoietic stem progenitor cells (HSPCs) to insert an expression cassette containing IDUA cDNA, which is impaired in MPS I. CRISPR/Cas9-edited HSPCs showed stable gene insertion while preserving stemness and engraftment potential [39,40].