The purpose of the study is to evaluate the safety, tolerability of ascending doses of SB-318. SB-318 is an intravenously delivered Zinc Finger Nuclease (ZFN) Therapeutic for genome editing. It inserts a correct copy of the α-L-iduronidase (IDUA) gene into the Albumin locus in hepatocytes with the goal of lifelong therapeutic production of the IDUA enzyme.