The primary objective of this study is to provide ongoing treatment of HGT-1111 to patients who have completed study HGT-MLD-048 (previously study rhASA-03 - NCT00633139) until HGT-1111 is commercially available or the study is terminated by the Sponsor, provided no safety concerns have emerged. The secondary objective of this study is to monitor disease progression and the safety profile of HGT-1111 administered to patients who have completed study HGT-MLD-048 (NCT00633139).