 Study TKT024EXT was a long-term, single-arm, open-label extension of Study TKT024, a one year Phase 2Phase 3 registration study. The primary objective of this extension study was to collect long-term safety and clinical outcome data in Mucopolysaccharidosis II MPS II, also known as Hunter Syndrome, from the Phase 2Phase 3 Study TKT024. All patients enrolling into this study received weekly active treatment with idursulfase, the primary dosing regimen investigated in Study TKT024. 