HUNTER SYNDROME

ALTERNATE NAMES

Mucopolysaccharidosis type II; Iduronate sulfatase deficiency; MPS Disorder; MPS II

DESCRIPTION

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, PHYSICAL FINDINGS, AND ICD-9-CM CODING

Definitive diagnostic lab 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: Coarse facial features, thickened skin, narrowing of the cervical spinal canal (spinal stenosis), short stature, enlarged tongue (macroglossia) and vocal cords, enlarged liver and spleen, retinal degeneration, contractures of the joints, leaky heart valves, umbilical or inguinal hernia, carpal tunnel syndrome, buildup of cerebrospinal fluid in the brain (hydrocephalus) and enlarged head (macrocephaly).

ICD-9: 277.5 Mucopolysaccharidosis

ONSET AND PROGRESSION

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.

TREATMENT

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.

SUGGESTED PROGRAMMATIC ASSESSMENT*

Suggested MER for Evaluation: Enzyme assay for iduronate sulfatase; evidence of progressive neuro-developmental delay; physical examination of the eyes, heart, liver, spleen, respiratory, neurologic and musculoskeletal systems.

Suggested Listings for Evaluation:

DETERMINATION

LISTING

REMARKS

Meets Listing

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 110.08B.

Medical Equals