ALTERNATE NAMES

Alpha-L-iduronate deficiency; Attenuated MPS I; Mucopolysaccharidosis type I; Hurler-Pfaundler Syndrome; Hurler Syndrome; Hurler Syndrome Type IH; Hurler-Scheie Syndrome; Lipochondrodystrophy; Pfaundler-Hurler Syndrome; Lysosomal Storage Disease – Mucopolysaccharidosis Type I; MPS I H; MPS 1 H/S; MPS I S;

DESCRIPTION

MPS I is one of a rare group of inherited diseases known as mucopolysaccharidoses. In this syndrome, the body is unable to break down long chains of sugar molecules called glycosaminoglycans, or mucopolysaccharides. The molecules are found throughout the body, often in mucus and in fluid around the joints. Because the body is unable to make an enzyme called lysosomal alpha-L-iduronidase, the sugar molecules build up and accumulate in blood cells, cartilage, bone and connective tissues leading to permanent damage in multiple body organs. MPS I is the most severe type of mucopolysaccharidosis. Symptoms can range from mild to severe. Symptoms of MPS I most often appear between ages 3 and 8. Some individuals have skeletal and joint deformities that affect mobility.

DIAGNOSTIC TESTING, PHYSICAL FINDINGS, AND ICD-9-CM/ICD-10-CM CODING

Diagnostic testing:

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  Genetic testing for mutations in the alpha-L-iduronidase (IDUA) gene;

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  X-rays of the spine showing dysostosis multiplex;

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  Urine testing may reveal excess glycosaminoglycans (heparin sulfate/ dermatan sulfate);

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  Echocardiogram; pulmonary function testing;

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  EMG/ NCS nerve conduction studies;

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  CT scan/ MRI may be supportive; and

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  Slit lamp examination.

Physical findings: Individuals with this condition have:

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  Distinct facial features (flat face, depressed nasal bridge, bulging forehead);

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  Short stature;

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  Enlarged tongue (macroglossia) and vocal cords;

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  Clouding of corneas;

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  Joint stiffness;

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  Claw hand;

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  Enlarged liver and spleen (hepatosplenomegaly);

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  Leaky heart valves/enlarged heart;

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  Umbilical and inguinal hernia;

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  Carpal tunnel syndrome;

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  Hydrocephalus (buildup of fluid around brain);

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  Macrocephaly (large head); and

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  Cervical spinal stenosis (narrowing of spinal cord).

ICD-9: 277.5

ICD-10: E76.0

PROGRESSION

Infants may appear normal at birth. Signs most often appear between the ages of 6 and 24 months. The severe form is associated with rapid progression and decreases in intellectual functioning, developmental delay and/ or regression, and death occurs by age 10. Heart disease and pulmonary complications are the major causes of death.

TREATMENT

There is no cure for this disorder. Enzyme replacement therapy has been tried with limited success. Bone marrow transplantation has also been attempted with mixed results. Other treatment depends on the organs that are affected and are focused on improving the individual’s quality of life.

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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  Laboratory tests showing results of genetic testing for mutations in the IDUA gene;

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  Imaging studies, e.g. X-rays, CT scan/MRI

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  Urine testing;

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  Echocardiogram;

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  Pulmonary function testing;

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  EMG/ NCS nerve conduction studies; and

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  Slit lamp examination.

Suggested Listings for Evaluation:

DETERMINATION

LISTING

REMARKS

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