Abstract
This is a four-part prospective, multicenter, multiregional observational study of patients with mucopolysaccharidosis type II (MPS II), also known as Hunter syndrome, to assess biomarkers potentially related to disease severity and/or treatment response and prospectively assess the progression of disease in participants with MPS II who are aged 2 through 10 years (Part 1), 2 through 30 years (Part 2), < 8 years (Part 3), and 6 to < 17 years (Part 4) at the time of enrollment.