Iduronate-2-sulfatase is required for the lysosomal degradation of heparan sulfate and dermatan sulfate. Mutations in this X-chromosome gene that result in enzymatic deficiency lead to the sex-linked Mucopolysaccharidosis Type II, also known as Hunter Syndrome. Iduronate-2-sulfatase has a strong sequence homology with human arylsulfatases A, B, and C, and human glucosamine-6-sulfatase. A splice variant of this gene has been described.

Two forms of MPS II are distinguishable clinically. A severe form (called MPS IIA in my nomenclature) has progressive mental retardation and physical disability and death before age 15 years in most cases. A mild form (called MPS IIB) is compatible with survival to adulthood, and reproduction is known to have occurred.