ALTERNATE NAMES

Hunter Syndrome; I2S Deficiency; Iduronate Sulfatase Deficiency; Lysosomal Storage Disease – Mucopolysaccharidosis Type II; MPS Disorder

DESCRIPTION

MPS II 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 MPS II begins shortly after age two. 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, PHYSICAL FINDINGS, AND ICD-9-CM/ICD-10-CM CODING

Diagnostic testing:

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  Enzyme studies documenting absent or deficient levels of iduronate-2-sulfatase (I2S);

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  Genetic testing for change (mutation) in the iduronate sulfatase gene, and urine testing for heparan sulfate and dermatan sulfate;

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  Pulmonary function testing (PFT);

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  Echocardiogram;

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  Electromyography (EMG)/nerve conduction study (NCS);

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  Computed tomography (CT) scan/magnetic resonance imaging (MRI) may be supportive; and

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  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;

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  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

ICD-10: E76.1

PROGRESSION

The more severe form of MPS II usually has a disease onset between ages two and four 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.

TREATMENT

There is no curative treatment for MPS II. Treatment with idursulfase (Elaprase) has been shown to improve walking when given early. Medical therapy is directed at treating the systemic complications of the disorder.

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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  PFT;

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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:

DETERMINATION

LISTING

REMARKS

Meets

110.08 B

This congenital disorder interferes with mental development and has progressive loss of motor function. Early-onset form is most severe, and is appropriately evaluated under 110.08 B.

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