COMPASSIONATE
ALLOWANCE INFORMATION |
MPS II - HUNTER SYNDROME
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ALTERNATE NAMES
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Mucopolysaccharidosis type II; Iduronate sulfatase deficiency; MPS Disorder; MPS II;
I2S Deficiency; Lysosomal Storage Disease – Mucopolysaccharidosis Type II
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DESCRIPTION
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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.
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DIAGNOSTIC TESTING, PHYSICAL FINDINGS, AND ICD-9-CM CODING
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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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Narrowing of the cervical spinal canal (spinal stenosis);
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Enlarged tongue (macroglossia) and vocal cords;
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Enlarged liver and spleen (hepatosplenomegaly);
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Contractures of the joints;
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Leaky heart valves, umbilical or inguinal hernia;
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Buildup of cerebrospinal fluid in the brain (hydrocephalus); and
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Enlarged head (macrocephaly).
ICD-9: 277.5
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TREATMENT
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There is no curative treatment for Hunter syndrome. 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.
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PROGRESSION
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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.
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SUGGESTED PROGRAMMATIC ASSESSMENT*
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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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EMG/NCS (nerve conduction studies);
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Suggested Listings for Evaluation:
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DETERMINATION
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LISTING
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REMARKS
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Meets
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110.08 B
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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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Equals
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*Adjudicators may, at their discretion, use the Medical Evidence of Record or the
listings suggested to evaluate the claim. However, the decision to allow or deny the
claim rests with the adjudicator.
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