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NINDS Mucolipidoses Information Page

Condensed from Mucolipidoses Fact Sheet

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What are Mucolipidoses?

The mucolipidoses (ML) are a group of inherited metabolic diseases that affect the body’s ability to carry out the normal turnover of various materials within cells. In ML, abnormal amounts of carbohydrates and fatty materials (lipids) accumulate in cells. Because our cells are not able to handle such large amounts of these substances, damage to the cells occurs, causing symptoms that range from mild learning disabilities to severe intellectual impairment and skeletal deformities.

The group includes four diseases:

  • Mucolipidosis I (sialidosis)
  • Mucolipidosis II (inclusion-cell, or I-cell, disease)
  • Mucolipidosis III (pseudo-Hurler polydystrophy)
  • Mucolipidosis IV

The MLs are classified as lysosomal storage diseases because they involve increased storage of substances in the lysosomes, which are specialized sac-like components within most cells. Individuals with ML are born with a genetic defect in which their bodies either do not produce enough enzymes or, in some instances, produce ineffective forms of enzymes. Without functioning enzymes, lysosomes cannot break down carbohydrates and lipids and transport them to their normal destination. The molecules then accumulate in the cells of various tissues in the body, leading to swelling and damage of organs.

The mucolipidoses occur only when a child inherits two copies of the defective gene, one from each parent. When both parents carry a defective gene, each of their children faces a one in four chance of developing one of the MLs.

Is there any treatment?

No cures or specific therapies for ML currently exists.  Therapies are generally geared toward treating symptoms and providing supportive care to the child.  For individuals with corneal clouding, surgery to remove the thin layer over the eye has been shown to reduce the cloudiness in the eye.  However, this improvement may be only temporary.   Physical and occupational therapy may help children with motor delays.  Children with language delays may benefit from speech therapy.    Children at risk for failure to thrive (growth failure) may need nutritional supplements, especially iron and vitamin B12 for persons with ML IV.  Respiratory infections should be treated immediately and fully with antibiotics.

What is the prognosis?

Symptoms of ML can be congenital (present at birth) or begin in early childhood or adolescence. Early symptoms can include skeletal abnormalities, vision problems and developmental delays. Over time, many children with ML develop poor mental capacities, have difficulty reaching normal developmental milestones, and, in many cases, eventually die of the disease.

What research is being done?

The mission of the National Institute of Neurological Disorders and Stroke (NINDS) is to seek fundamental knowledge of the brain and nervous system and to use that knowledge to reduce the burden of neurological disease. Investigators are conducting studies to determine the effects of ML genetic mutations in various animal models of the disease.  Studying the disease mechanisms in these models may allow scientists to develop treatments for people with an ML disorder.Clinical trials include a natural history of individuals with ML IV, to better understand the disease and identify potential outcomes, and longitudinal studies to better understand disease progression, assess current therapies, and identify potential treatments.

NIH Patient Recruitment for Mucolipidoses Clinical Trials


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Mucolipidosis IV (ML4) Foundation
3500 Piedmont Road, Suite 500
Atlanta, GA 30305
Tel: 877-ML4-5459 (654-5459)

National MPS Society, Inc.
PO Box 14686
Durham, NC 27709-4686
Tel: 877-MPS-1001; 919-806-0101
Fax: 919-806-2055

National Organization for Rare Disorders (NORD)
55 Kenosia Avenue
Danbury, CT 06810
Tel: 203-744-0100; Voice Mail: 800-999-NORD (6673)
Fax: 203-798-2291

National Tay-Sachs and Allied Diseases Association
2001 Beacon Street
Suite 204
Boston, MA 02135
Tel: 800-90-NTSAD (906-8723)
Fax: 617-277-0134

ISMRD-International Advocate For Glycoprotein Storage Diseases
20880 Canyon View Drive
Saratoga, CA 95070
Tel: 734-449-1190
Fax: 734-449-9038

Genetic Alliance
4301 Connecticut Avenue, N.W.
Suite 404
Washington, DC 20008-2369
Tel: 202-966-5557; 800-336-GENE (4363)
Fax: 202-966-8553

National Society of Genetic Counselors
401 N. Michigan Avenue
Chicago, IL 60611
Tel: 312-321-6834
Fax: 312-673-6972

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Prepared by:
Office of Communications and Public Liaison
National Institute of Neurological Disorders and Stroke
National Institutes of Health
Bethesda, MD 20892

NINDS health-related material is provided for information purposes only and does not necessarily represent endorsement by or an official position of the National Institute of Neurological Disorders and Stroke or any other Federal agency. Advice on the treatment or care of an individual patient should be obtained through consultation with a physician who has examined that patient or is familiar with that patient's medical history.

All NINDS-prepared information is in the public domain and may be freely copied. Credit to the NINDS or the NIH is appreciated.

Last Modified February 23, 2016