Self-complementary adeno-associated virus serotype 9 carrying the human SGSH gene under the control of a U1a promoter (scAAV9.U1a.hSGSH) will be delivered one time through a venous catheter inserted into a peripheral limb vein. The vector will be delivered undiluted over 5 to 50 minutes, under light to moderate sedation as needed. Dosing volume will be approximately 0.5 to 3 mL/kg, depending on final vector product concentration and subject cohort. A tapering course of prophylactic enteral prednisone or prednisolone will be administered