MPS II – Hunter syndrome is a rare, inherited disease in which the sugar molecules (mucopolysaccharides) are not broken down correctly and build up in the body. The condition is caused by a lack of enzyme iduronate sulfatase. The early-onset (severe) form of Hunter syndrome begins shortly after age 2. The symptoms include aggressive behavior, hyperactivity, mental function decline, severe intellectual disability and spasticity. Other symptoms may include carpal tunnel syndrome, coarse facial features, deafness, hairy body (hypertrichosis), joint stiffness, and a large head (macrocephaly). Individuals with this disorder may experience the following signs: abnormal retina, heart murmur and leaky heart valves, enlarged liver (hepatomegaly) enlarged spleen (splenomegaly), inguinal hernia, and joint contractures.

Diagnostic testing: Enzyme studies documenting absent or deficient levels of iduronate-2-sulfatase (I2S). Genetic testing for change (mutation) in the iduronate sulfatase gene, and urine testing for heparan sulfate and dermatan sulfate. Pulmonary function testing, echocardiogram, EMG/NCS (nerve conduction studies), CT scan/ MRI may be supportive. Slit lamp examination.

Physical findings:

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  Coarse facial features;

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  Thickened skin;

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  Narrowing of the cervical spinal canal (spinal stenosis);

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  Short stature;

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  Enlarged tongue (macroglossia) and vocal cords;

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  Enlarged liver and spleen (hepatosplenomegaly);

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  Retinal degeneration;

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  Contractures of the joints;

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  Leaky heart valves, umbilical or inguinal hernia;

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  Carpal tunnel syndrome;

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  Buildup of cerebrospinal fluid in the brain (hydrocephalus); and

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  Enlarged head (macrocephaly).

ICD-9: 277.5

The more severe form of Hunter syndrome usually has a disease onset between ages 2 and 4 years. Mental impairment and developmental decline is usually noticed at 18-24 months with progressive loss of motor skills. Death from upper airway obstruction or heart failure occurs by age 15.

SUGGESTED PROGRAMMATIC ASSESSMENT*

Suggested MER for Evaluation:

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  Clinical history and examination that describes the diagnostic features of the impairment;

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  Enzyme assay for iduronate sulfatase;

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  Pulmonary function testing;

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  Echocardiogram;

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  EMG/NCS (nerve conduction studies);

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  CT scan/ MRI scan, and

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  Slit lamp examination.

Suggested Listings for Evaluation:

REMARKS