Hunter syndrome is an inherited disease in which long chains of sugar molecules (
Mucopolysaccharidosis type II, Iduronate sulfatase deficiency
Causes, incidence, and risk factors
Hunter syndrome is an inherited condition. Boys are most often affected.
The condition is caused by a lack of the
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):
- Aggressive behavior
- Mental function gets worse over time
intellectual disability Spasticity
Late (mild) form:
- Mild to no mental deficiency
Carpal tunnel syndrome
- Coarse features of the face
Deafness(gets worse over time)
- Increased hair (
- Joint stiffness
- Large head (
Signs and tests
Signs of the disorder include:
retina(back of the eye)
- Decreased iduronate sulfatase enzyme in blood serum or cells
Heart murmurand leaky heart valves
Enlarged liver (
Enlarged spleen (
Tests may include:
- Enzyme study
- Genetic testing for 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.
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.
- 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
Calling your health care provider
Call your health care provider if:
You or your child has a group of these symptoms
You know you are a genetic carrier and are considering having children
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.