Mucopolysaccharidosis type I (MPS I) is a severe disease due to deficiency of the lysosomal hydrolase α-L-iduronidase (IDUA) and the subsequent accumulation of the glycosaminoglycans (GAG)， leading to progressive， systemic disease and a shortened lifespan. Current treatment options consist of hematopoietic stem cell transplantation， which carries significant mortality and morbidity risk， and enzyme replacement therapy， which requires lifelong infusions of replacement enzyme; neither provides adequate therapy， even in combination. A novel in vivo genome-editing approach is described in the murine model of Hurler syndrome. A corrective copy of the IDUA gene is inserted at the albumin locus in hepatocytes， leading to sustained enzyme expression， secretion from the liver into circulation， and subsequent uptake systemically at levels sufficient for correction of metabolic disease (GAG substrate accumulation) and prevention of neurobehavioral deficits in MPS I mice. This study serves as a proof-of-concept for this platform-based approach that should be broadly applicable to the treatment of a wide array of monogenic diseases.