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By Mayo Clinic staffHunter syndrome is one type of a group of inherited metabolic disorders called mucopolysaccharidosis (MPS), and Hunter syndrome is referred to as MPS II. There are two subtypes of Hunter syndrome, MPS IIA and MPS IIB. Symptoms vary according to subtype.
Type MPS IIA (early onset)
Early-onset Hunter syndrome (MPS IIA) is the more severe of the two types and usually appears around age 2 and up to age 4. This form of the disorder may result in profound mental retardation by late childhood. Children with this form of the syndrome usually don't survive beyond their teens.
Signs and symptoms of MPS IIA include:
- A decline in development, which usually appears between ages 1 1/2 and 3, followed by a progressive loss of skills
- Coarse facial features, including thickening of the lips, tongue and nostrils
- Abnormal bone size or shape and other skeletal irregularities
- Enlarged internal organs, such as the liver and spleen, resulting in a distended abdomen
- Respiratory difficulties including sleep apnea, a condition in which breathing intermittently stops during sleep
- Cardiovascular disorders, such as progressive thickening of heart valves, high blood pressure (hypertension) and obstruction of blood vessels
- Vision loss or impairment from degeneration of cells that capture light and buildup of cellular debris in the brain causing pressure on the optic nerve and eye
- Skin lesions on the back and upper arms
- Progressive loss of hearing
- Aggressive behavior
- Stunted growth
- Joint stiffness
- Diarrhea
Type MPS IIB (late onset)
Late-onset Hunter syndrome (MPS IIB) is milder and causes less severe symptoms that appear much later. This form is usually diagnosed after age 10, and may not be detected until adulthood. Intellectual and social development usually is nearly normal, but the condition may affect verbal and reading skills. People with this type of Hunter syndrome can live into their 50s.
Signs and symptoms of MPS IIB include:
- Abnormal bone size or shape and other skeletal irregularities, but less severe than in MPS IIA
- Somewhat stunted growth
- Poor peripheral vision
- Joint stiffness
- Hearing loss
- Diarrhea
- Sleep apnea
When to see a doctor
Hunter syndrome isn't a common disorder, but if you notice changes in your child's facial appearance, a loss of previously acquired skills, or other signs or symptoms listed above, talk to your child's primary care doctor. He or she can perform an evaluation and help you decide if you need to see a specialist or seek out further testing.