Hunter Syndrome (MPS II)

Clinical Characteristics
Ocular Features: 

Corneal clouding may be noted as early as 6 months of age but is usually absent. When present it is milder than in some other forms of mucopolysaccharidosis.  A pigmentary retinopathy with variable severity is often present.  The disc may be elevated and appears swollen.  Secondary optic atrophy may be seen in long standing cases.

Systemic Features: 

Mild to severe developmental delays are common and mental retardation has been reported in some cases.  There is often 'pebbling' of the skin over the neck and chest.  Joint stiffness, short stature, and skeletal deformities are common.   Many have short necks, a protuberant abdomen, a broad chest, and facial coarseness.  Hepatosplenomegaly, hearing loss, hernias, and carpal tunnel syndrome are often present.  The skull is large with a J-shaped sella, the vertebral bodies are hypoplastic anteriorly, the pelvis and femoral heads are hypoplastic and the diaphyses are expanded.

A severe form, type A, has its onset in the first two to four years of life, with more rapid progression and death commonly by adolescence.  Many patients have obstructive pulmonary disease and heart failure.  The IDS deficiency is similar to that of type B which is less severe and compatible with life into the 7th decade.  Intelligence is often normal in type B.


Hunter syndrome, or MPS II, is one of seven lysosomal enzyme deficiencies responsible for the degradation of mucopolysaccharides, and the only one known to be X-linked (Xq28).  The mutation in IDS leads to a deficiency of iduronate sulfatase resulting in accumulation of dermatan and heparin sulfate.  Rare affected females may have chromosomal deletions instead of a simple mutation in IDS.

Treatment Options: 

Various therapies are under development including enzyme replacement, gene transfers, and bone marrow transplantation.  Human iduronate-2-sulfatase (Idursulfase) has been used with encouraging signs but it is too early to determine the long term effectiveness.

Article Title: 


Vellodi A, Young E, Cooper A, Lidchi V, Winchester B, Wraith JE. Long-term follow-up following bone marrow transplantation for Hunter disease. J Inherit Metab Dis. 1999 Jun;22(5):638-48.

PubMedID: 10399096

Froissart R, Maire I, Millat G, Cudry S, Birot AM, Bonnet V, Bouton O, Bozon D. Identification of iduronate sulfatase gene alterations in 70 unrelated Hunter patients. Clin Genet. 1998 May;53(5):362-8.

PubMedID: 9660053

Braun SE, Aronovich EL, Anderson RA, Crotty PL, McIvor RS, Whitley CB. Metabolic correction and cross-correction of mucopolysaccharidosis type II (Hunter syndrome) by retroviral-mediated gene transfer and expression of human iduronate-2-sulfatase. Proc Natl Acad Sci U S A. 1993 Dec 15;90(24):11830-4.

PubMedID: 8265633

Collins ML, Traboulsi EI, Maumenee IH. Optic nerve head swelling and optic atrophy in the systemic mucopolysaccharidoses. Ophthalmology. 1990 Nov;97(11):1445-9. PubMed PMID: 2123975.

PubMedID: 2123975