Hunter syndrome is an inherited disease in which long chains of sugar molecules (mucopolysaccharides
) are not broken down correctly and build up in the body.
Mucopolysaccharidosis type II, Iduronate sulfatase deficiency
Hunter syndrome is an inherited condition, where the affected gene is on the X chromosome. Therefore, boys are most often affected.
The condition is caused by a lack of the enzyme
iduronate sulfatase. Without this enzyme, mucopolysaccharides build up in various body tissues, causing damage.
The early-onset, severe form of the disease begins shortly after age 2. A late-onset, mild form causes less severe symptoms to appear later in life.
Juvenile form (early-onset, severe form):
Late (mild) form:
- Mild to no mental deficiency
Exams and Tests
Signs of the disorder include:
Tests may include:
- Enzyme study
- Genetic testing for a change (mutation) in the iduronate sulfatase gene
- Urine test for heparan sulfate and dermatan sulfate
The U.S. Food and Drug Administration has approved the first treatment for Hunter syndrome. The medicine, called idursulfase (Elaprase), is given through a vein (intravenously). Talk to your doctor for more information.
Bone marrow transplant
has been tried for the early-onset form, but the results can vary.
Each health problem should be treated separately.
People with the early-onset (severe) form usually live for 10 - 20 years. People with the late-onset (mild) form usually live 20 - 60 years.
- Airway obstruction
- Carpal tunnel syndrome
- Hearing loss that gets worse over time
- Loss of ability to complete daily living activities
- Joint stiffness that leads to contractures
- Mental function that gets worse over time
When to Contact a Medical Professional
Call your health care provider if:
Genetic counseling is recommended for couples who want to have children and who have a family history of Hunter syndrome. Prenatal testing is available. Carrier testing for female relatives of affected males is available at a few centers.
Muenzer J, Wraith JE, Beck M, et al. A phase II/III clinical study of enzyme replacement therapy with idursulfase in mucopolysaccharidosis II (Hunter syndrome). Genet Med. 2006 Aug;8(8):465-73.
Wraith JE. Mucopolysaccharidoses and oligosaccharidoses. In: Saudubray JM, van den Berghe G, Walter JH, eds. Inborn Metabolic Diseases: Diagnosis and Treatment. 5th ed. New York, NY: Springer; 2012:chap 40.
Chad Haldeman-Englert, MD, FACMG, Wake Forest School of Medicine, Department of Pediatrics, Section on Medical Genetics, Winston-Salem, NC. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Bethanne Black, and the A.D.A.M. Editorial team.