National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Mucopolysaccharidosis type I


Other Names:
MPS 1; Attenuated MPS I (subtype, includes Hurler-Scheie and Scheie syndrome); Severe MPS I (subtype, also known as Hurler syndrome); MPS 1; Attenuated MPS I (subtype, includes Hurler-Scheie and Scheie syndrome); Severe MPS I (subtype, also known as Hurler syndrome); Hurler syndrome (subtype); Hurler-Scheie syndrome (subtype); Scheie syndrome (subtype) formerly known as Mucopolysaccharidosis type V); Alpha-L-Iduronidase deficiency; IDUA deficiency; MPS I See More
Categories:
Subtypes:
This disease is grouped under:
Mucopolysaccharidosis type I (MPS I) is a condition that affects many parts of the body. It is a progressively debilitating disorder; however, the rate of progression varies among affected individuals. MPS I is caused by mutations in the IDUA gene. These mutations lead to reduced levels or the complete lack of the IDUA enzyme. Without the proper amount of this enzyme, large sugar molecules called glycosaminoglycans (GAGs) accumulate within cells called lysosomes. This causes the lysosomes to increase in size, causing many different organs and tissues of the body to become enlarged. This leads to the medical problems seen in the condition.[1][2] 

MPS I was once divided into three separate syndromes: Hurler syndrome, Hurler-Scheie syndrome, and Scheie syndrome, listed from most to least severe. Because no biochemical differences have been identified and the clinical findings overlap, the condition is now divided into two subtypes, severe MPS I and attenuated MPS I.[1][2] People with severe MPS I typically have an earlier onset of symptoms, a decline in intellectual function, and a shorter lifespan. Although there is no cure for MPS I, bone marrow transplant and enzyme replacement therapy are treatment options that may help manage the symptoms of this condition.[1]
Last updated: 2/3/2016
The signs and symptoms of mucopolysaccharidosis type I (MPS I) are not present at birth, but they begin to appear during childhood. People with severe MPS I develop the features of this condition earlier than those with attenuated MPS I. The following list includes the most common signs and symptoms of MPS I:[1]
  • Enlarged head, lips, cheeks, tongue, and nose
  • Enlarged vocal cords, resulting in a deep voice
  • Frequent upper respiratory infections
  • Sleep apnea
  • Hydrocephalus
  • Hepatosplenomegaly (enlarged liver and spleen)
  • Umbilical hernia
  • Inguinal hernia
  • Hearing loss
  • Recurrent ear infections 
  • Corneal clouding
  • Carpal tunnel syndrome
  • Narrowing of the spinal canal (spinal stenosis)
  • Heart valve abnormalities, which can lead to heart failure
  • Short stature
  • Joint deformities (contractures)
  • Dysostosis multiplex (generalized thickening of most long bones, particularly the ribs)
  • Developmental delays and regression 
Last updated: 5/23/2016

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Showing of 66 |
Medical Terms Other Names
Learn More:
HPO ID
80%-99% of people have these symptoms
Abnormal form of the vertebral bodies 0003312
Abnormality of epiphysis morphology
Abnormal shape of end part of bone
0005930
Abnormality of the metaphysis
Abnormality of the wide portion of a long bone
0000944
Abnormality of the voice
Voice abnormality
0001608
Chronic otitis media
Chronic infections of the middle ear
0000389
Coarse facial features
Coarse facial appearance
0000280
Corneal opacity 0007957
Generalized hirsutism
Excessive hairiness over body
0002230
Inguinal hernia 0000023
Joint stiffness
Stiff joint
Stiff joints
[ more ] 		0001387
Mucopolysacchariduria 0008155
Scoliosis 0002650
Short stature
Decreased body height
Small stature
[ more ] 		0004322
Sinusitis
Sinus inflammation
0000246
Splenomegaly
Increased spleen size
0001744
Split hand
Claw hand
Claw hand deformities
Claw hands
Claw-hand deformities
Split-hand
[ more ] 		0001171
30%-79% of people have these symptoms
Abnormal nasal morphology
Abnormal of nasal shape
Abnormal of shape of nose
[ more ] 		0005105
Abnormality of the hip bone
Abnormality of the hips
0003272
Abnormality of the tonsils 0100765
Apnea 0002104
Arthralgia
Joint pain
0002829
Cough
Coughing
0012735
Depressed nasal bridge
Depressed bridge of nose
Flat bridge of nose
Flat nasal bridge
Flat, nasal bridge
Flattened nasal bridge
Low nasal bridge
Low nasal root
[ more ] 		0005280
Developmental regression
Loss of developmental milestones
Mental deterioration in childhood
[ more ] 		0002376
Dolichocephaly
Long, narrow head
Tall and narrow skull
[ more ] 		0000268
Enlarged thorax
Wide rib cage
0100625
Everted lower lip vermilion
Drooping lower lip
Outward turned lower lip
[ more ] 		0000232
Full cheeks
Apple cheeks
Big cheeks
Increased size of cheeks
Large cheeks
[ more ] 		0000293
Gingival overgrowth
Gum enlargement
0000212
Glaucoma 0000501
Intellectual disability
Mental deficiency
Mental retardation
Mental retardation, nonspecific
Mental-retardation
[ more ] 		0001249
Low anterior hairline
Low frontal hairline
Low-set frontal hairline
[ more ] 		0000294
Macrocephaly
Increased size of skull
Large head
Large head circumference
[ more ] 		0000256
Malabsorption
Intestinal malabsorption
0002024
Microdontia
Decreased width of tooth
0000691
Paresthesia
Pins and needles feeling
Tingling
[ more ] 		0003401
Recurrent respiratory infections
Frequent respiratory infections
Multiple respiratory infections
respiratory infections, recurrent
Susceptibility to respiratory infections
[ more ] 		0002205
Retinopathy
Noninflammatory retina disease
0000488
Sensorineural hearing impairment 0000407
Thick lower lip vermilion
Increased volume of lower lip
Plump lower lip
Prominent lower lip
[ more ] 		0000179
Thick nasal alae 0009928
Widely spaced teeth
Wide-spaced teeth
Widely-spaced teeth
[ more ] 		0000687
5%-29% of people have these symptoms
Abnormal aortic valve morphology 0001646
Abnormal tendon morphology
Abnormal shape of tendon
0100261
Avascular necrosis
Death of bone due to decreased blood supply
0010885
Congestive heart failure
Cardiac failure
Cardiac failures
Heart failure
[ more ] 		0001635
Hemiplegia/hemiparesis
Paralysis or weakness of one side of body
0004374
Hydrocephalus
Too much cerebrospinal fluid in the brain
0000238
Hypertrophic cardiomyopathy
Enlarged and thickened heart muscle
0001639
Joint dislocation
Joint dislocations
Recurrent joint dislocations
[ more ] 		0001373
Optic atrophy 0000648
Spinal canal stenosis
Narrow spinal canal
0003416
Visual impairment
Impaired vision
Loss of eyesight
Poor vision
[ more ] 		0000505
Percent of people who have these symptoms is not available through HPO
Aortic regurgitation 0001659
Autosomal recessive inheritance 0000007
Dysostosis multiplex 0000943
Hirsutism
Excessive hairiness
0001007
Kyphosis
Hunched back
Round back
[ more ] 		0002808
Micrognathia
Little lower jaw
Small jaw
Small lower jaw
[ more ] 		0000347
Mitral regurgitation 0001653
Obstructive sleep apnea 0002870
Pulmonary arterial hypertension
Increased blood pressure in blood vessels of lungs
0002092
Thick vermilion border
Full lips
Increased volume of lip
Plump lips
Prominent lips
Thick lips
[ more ] 		0012471
Thickened skin
Thick skin
0001072
Tracheal stenosis
Narrowing of windpipe
0002777
Umbilical hernia 0001537
Showing of 66 |
Last updated: 7/1/2020
Mutations in the IDUA gene cause mucopolysaccharidosis type I (MPS I). The IDUA gene provides instructions for producing an enzyme (alpha-L-iduronidase) that is involved in the breakdown of large sugar molecules called glycosaminoglycans (GAGs). Mutations in the IDUA gene reduce or completely eliminate the function of alpha-L-iduronidase. This leads to the accumulation of GAGs within cells, specifically inside the lysosomes. Lysosomes are compartments in the cell that digest and recycle different types of molecules. Conditions that cause molecules to build up inside the lysosomes, including MPS I, are called lysosomal storage disorders. The accumulation of GAGs increases the size of the lysosomes, which is why many tissues and organs are enlarged in this disorder.[1][3]
Last updated: 5/23/2016
Mucopolysaccharidosis type I (MPS I) is inherited in an autosomal recessive manner.[1] This means that to be affected, a person must have a mutation in both copies of the responsible gene in each cell. Affected people inherit one mutated copy of the gene from each parent, who is referred to as a carrier. Carriers of an autosomal recessive condition typically do not have any signs or symptoms (they are unaffected). When 2 carriers of an autosomal recessive condition have children, each child has a:
  • 25% (1 in 4) chance to be affected
  • 50% (1 in 2) chance to be an unaffected carrier like each parent
  • 25% chance to be unaffected and not be a carrier
If you are concerned about your risks to be a carrier of MPS I, we would recommend you consult with a genetics specialist, such as a geneticist or a genetic counselor. See our page on how to find a genetics clinic to identify a local genetics specialist.  
Last updated: 5/23/2016

Making a diagnosis for a genetic or rare disease can often be challenging. Healthcare professionals typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis. The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare professional.

Newborn Screening

  • Baby's First Test is the nation's newborn screening education center for families and providers. This site provides information and resources about screening at the local, state, and national levels and serves as the Clearinghouse for newborn screening information.
Management of mucopolysaccharidosis type I (MPS I) requires a multidisciplinary team given the wide range of symptoms. This team may include: primary care; cardiology; pulmonology; gastroenterology; neurology; ear, nose, and throat specialists; audiology; ophthalmology; orthopedics; physical therapy; dental; and developmental specialists.[4]

The two main treatment options for MPS I include hematopoietic stem cell transplant (HSCT) and enzyme replacement therapy (ERT). Both of these treatments work by replacing the missing IDUA enzyme (alpha-L-iduronidase).[1]

HSCT is considered standard of care for individuals with severe MPS I; however, its success is dependent on timing of treatment. It is typically recommended that HSCT occur early in the disease process, prior to two years of age. Studies have shown that when successful, HSCT can improve facial, auditory, and cardiac manifestations. The effect on intellectual development is unclear with some studies suggesting an improvement, while others report a slowing of cognitive decline.[1][4]
 
A drug called laronidase or Aldurazyme is the enzyme replacement therapy for MPS I. Treatment with laronidase can improve problems with breathing, growth, the bones, joints and heart. However, this treatment is not expected to treat problems with mental development because laronidase cannot cross the blood-brain barrier.[1][4]

Last updated: 5/23/2016

FDA-Approved Treatments

The medication(s) listed below have been approved by the Food and Drug Administration (FDA) as orphan products for treatment of this condition. Learn more orphan products.

  • laronidase (Brand name: Aldurazyme) - Manufactured by BioMarin Pharmaceutical, Inc.
    FDA-approved indication: Treatment for patients with Hurler and Hurler-Scheie forms of Mucopolysaccharidosis I (MPS I) and for patients with the Scheie form who have moderate to severe symptoms
    National Library of Medicine Drug Information Portal

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

Related diseases are conditions that have similar signs and symptoms. A health care provider may consider these conditions in the table below when making a diagnosis. Please note that the table may not include all the possible conditions related to this disease.

Conditions with similar signs and symptoms from Orphanet
Mucopolysaccharidosis type VI (Maroteaux-Lamy syndrome; see this term) resembles mucopolysaccharidosis type I in many aspects, MPS VI patients, however, never have intellectual impairment. Mucopolysaccharidosis type II (see this term), an X-linked recessive disorder in which severe joint contractures are a characteristic symptom, also has many features in common with mucopolysaccharidosis type I.
Visit the Orphanet disease page for more information.

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

  • ClinicalTrials.gov lists trials that are related to Mucopolysaccharidosis type I. Click on the link to go to ClinicalTrials.gov to read descriptions of these studies.

    Please note: Studies listed on the ClinicalTrials.gov website are listed for informational purposes only; being listed does not reflect an endorsement by GARD or the NIH. We strongly recommend that you talk with a trusted healthcare provider before choosing to participate in any clinical study.
  • The Orphan Disease Center: MPS I Pilot Grant Program presents a request for applications (RFA) to support research on the development of improved therapies for people with syndromes due to MPS I including Hurler, Hurler-Scheie and Scheie. All individuals holding a faculty-level appointment at an academic or non-profit institution are eligible to respond to this RFA. Grants will be awarded for an initial period of 1 to 2 years at $150,000 direct costs per year (up to 10% indirect costs allowable); funding for a second year is predicated by adequate progress during year 1 and availability of funding. All applicants must first submit a letter of Interest (LOI) to be reviewed for consideration of a full application submission. LOIs are due no later than Monday, February 29, 2016 at 5pm (EST).

Patient Registry

  • The Lysosomal Disease Network is a team of doctors, nurses, research coordinators, and research labs throughout the U.S., working together to improve the lives of people with this condition through research. The Lysosomal Disease Network has a registry for patients who wish to be contacted about clinical research opportunities.

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

Living with a genetic or rare disease can impact the daily lives of patients and families. These resources can help families navigate various aspects of living with a rare disease.

Financial Resources

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

In-Depth Information

  • GeneReviews provides current, expert-authored, peer-reviewed, full-text articles describing the application of genetic testing to the diagnosis, management, and genetic counseling of patients with specific inherited conditions.
  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Mucopolysaccharidosis type I. Click on the link to view a sample search on this topic.

Selected Full-Text Journal Articles

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know. Submit a new question

  • I would like general information on mucopolysaccharidosis I (MPS I). My grandson was recently diagnosed with this condition and is currently undergoing enzyme therapy. Is a person with MPS I less likely to have brain damage if a bone marrow transplant is performed early?  See answer


  1. Clarke LA, Heppner J. Mucopolysaccharidosis Type I. GeneReviews. February 11, 2016; http://www.ncbi.nlm.nih.gov/books/NBK1162/.
  2. Mucopolysaccharidosis type I. Genetics Home Reference (GHR). December 2012; http://ghr.nlm.nih.gov/condition/mucopolysaccharidosis-type-i.
  3. IDUA. Genetics Home Reference. May 17, 2016; https://ghr.nlm.nih.gov/gene/IDUA.
  4. Joseph Muenzer, James E. Wraith, Lorne A. Clarke. Mucopolysaccharidosis I: Management and Treatment Guidelines. Pediatrics. January 2009; 123(1):http://www.ncbi.nlm.nih.gov/pubmed/19117856. Accessed 5/23/2016.