MPS
II
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ALTERNATE NAMES
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Hunter Syndrome; I2S Deficiency; Iduronate Sulfatase Deficiency; Lysosomal Storage
Disease – Mucopolysaccharidosis Type II; MPS Disorder; Mucopolysaccharidosis Type
II
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DESCRIPTION
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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 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/ICD-10-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;
-
•
EMG/NCS (nerve conduction studies);
-
•
CT scan/ MRI may be supportive; and
Physical findings:
-
•
Narrowing of the cervical spinal canal (spinal stenosis);
-
•
Enlarged tongue (macroglossia) and vocal cords;
-
•
Enlarged liver and spleen (hepatosplenomegaly);
-
•
Contractures of the joints;
-
•
Umbilical or inguinal hernia;
-
•
Buildup of cerebrospinal fluid in the brain (hydrocephalus); and
-
•
Enlarged head (macrocephaly).
ICD-9: 277.5
ICD-10: E76.1
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PROGRESSION
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The more severe form of MPS II 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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TREATMENT
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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.
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SUGGESTED PROGRAMMATIC ASSESSMENT*
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Suggested MER for Evaluation:
-
•
Clinical history and examination that describes the diagnostic features of the impairment;
-
•
Enzyme assay for iduronate sulfatase;
-
•
Pulmonary function testing;
-
-
•
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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