About Mucopolysaccharidosis Type I
Mucopolysaccharidosis Type I results from mutations in the IDUA gene encoding alpha-L-iduronidase, leading to inability to break down heparan sulfate and dermatan sulfate. These glycosaminoglycans accumulate in lysosomes throughout the body, causing progressive cellular dysfunction. The three clinical phenotypes reflect the degree of enzyme deficiency: severe Hurler form has minimal enzyme activity, Hurler-Scheie has intermediate activity, and Scheie has near-normal enzyme activity with limited tissue involvement. Disease manifestations reflect GAG accumulation in different tissues: skeletal tissue causes bone dysostosis, brain accumulation causes cognitive decline, connective tissue accumulation causes joint stiffness, and cardiac valve involvement can lead to heart disease.
Hurler syndrome, the most severe form, presents in early childhood with progressive coarse facial features, growth failure, developmental delay or regression, organomegaly, and progressive skeletal deformities. Cardiac involvement includes valve disease leading to heart failure. Respiratory involvement develops from upper airway narrowing and lung disease. Hearing loss is progressive. Intellectual disability becomes increasingly apparent in the second and third year of life. Without treatment, Hurler syndrome is life-limiting, with most patients dying by the second to third decade from cardiac or respiratory complications. Scheie and Hurler-Scheie forms progress more slowly and typically have normal or near-normal intelligence.
Common Symptoms of Mucopolysaccharidosis Type I
Recognizing the signs of Mucopolysaccharidosis Type I early can lead to faster diagnosis and better outcomes. Symptoms may vary in severity from person to person. If you or a loved one are experiencing any of the following, consider speaking with a specialist.
- Coarse facial features with progressive changes
- Growth deficiency and short stature
- Developmental delay and intellectual disability in severe forms
- Hepatosplenomegaly causing abdominal distension
- Joint stiffness and skeletal abnormalities
- Hearing loss and vision problems
Who Mucopolysaccharidosis Type I Affects
Hurler syndrome typically presents by age 2-3 years. Scheie syndrome may not manifest until school age or later. Hurler-Scheie intermediate form has onset in childhood. Affects males and females equally. Autosomal recessive inheritance. Occurs in all populations with variable prevalence.
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Help Paying for Mucopolysaccharidosis Type I Treatment
Charity funds and drugmaker programs for Mucopolysaccharidosis Type I, checked at the source. Pick your insurance to see what fits.
- From a charity · NORD RareCareMPS I (Hurler Syndrome) Medical Assistance fundOpen
Pays for: Medical and medication costs.
The foundation says: “Accepting Applications” - From a charity · NORD RareCareMPS I (Hurler Syndrome) Premium Copay Assistance fundOpen
Pays for: Insurance premiums and copays.
The foundation says: “Accepting Applications” - From a charity · The Assistance FundMPS I - Hurler Syndrome (Hurler-Scheie, Scheie) fundOpen
Pays for: Copays, coinsurance, deductibles and other health-related expenses.
The foundation says: “OPEN — Accepting New Patients. TAF is currently accepting new patient enrollments for this program.” - From a charity · National MPS SocietyFamily Assistance Program fundApply directly
Pays for: Specialized equipment and medical aids not covered by insurance (requires insurance denial and 10% family copay), up to $3,000 per year.
The foundation says: “Status not shown on page” - From a charity · National MPS SocietyMedical Travel Assistance Program fundApply directly
Pays for: Travel to out-of-town medical appointments more than 125 miles away (per year), up to $550 per year.
The foundation says: “Status not shown on page” - From a charity · National MPS SocietyJourney Assistance Program fundApply directly
Pays for: Items that ease daily life (40% of purchase price), up to $500 per year.
The foundation says: “Status not shown on page”
Side Effect Explorer
Real-world side effect reports from the FDA Adverse Event Reporting System (FAERS). Includes both FDA-approved drugs and investigational therapies from active clinical trials. Click any drug to see what patients reported.
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Genetic Testing
Genetic testing can confirm a diagnosis, guide treatment decisions, and identify family members who may be at risk.
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Trusted Mucopolysaccharidosis Type I Resources
Reputable organizations and medical references for learning more about Mucopolysaccharidosis Type I, including disease registries, foundation resources, and clinical guidelines.