Article: Mucopolysaccharidoses Information Page

What is Mucopolysaccharidoses?

Mucopolysaccharidoses consist of a group of inherited metabolic disorders caused by a deficiency of the specific lysosomal enzymes needed to break down mucopolysaccharides. Mucopolysaccharides are long chains of sugar molecules used to build connective tissues and organs in the body. When mutations occur in the genes for the enzymes involved in the normal turnover of mucopolysaccharides, excess amounts of them are stored in the body, causing progressive damage and, in most cases, eventual death. Because some of the excess mucopolysaccharides are excreted through the urine, diagnosis often can be made through clinical examination and urine tests. Prenatal diagnosis is also available. Eight clinical types and numerous subtypes of mucopolysaccharidoses have been identified. Although each type differs clinically, generally, people with mucopolysaccharidoses experience a period of normal development followed by a decline in physical and/or mental function. Some of the more common types include:

Mucopolysaccharidosis I(MPS I), which includes Hurler, Scheie, and Hurler/Scheie syndromes. Hurler syndrome-the most severe form of the mucopolysaccharidoses -occurs in infancy with symptoms such as clouding of the cornea and progressive physical and mental disability. Death usually occurs before age 10. Patients with Scheie syndrome experience milder symptoms and have normal intelligence, while those with Hurler/Scheie syndrome suffer from intermediate symptoms.

MPS II, also called Hunter syndrome, affects juveniles and includes a mild and a severe form. Signs of the severe form are joint stiffness, mental deterioration, dwarfing, and progressive deafness. Death usually occurs by age 15. Symptoms of the mild form include short stature, limitation of motion, and features such as an enlarged forehead, lips, and tongue and misaligned teeth. Life span may be normal.

Individuals with MPS III, or Sanfilippo syndrome, experience progressive dementia and mental deterioration in childhood. Death usually occurs in the late teens.

Symptoms of MPS IV, or Morquio syndrome, usually appear in infancy and may include severe dwarfing and corneal clouding. Intelligence is normal. Cardiac or respiratory disease may cause death in the third or fourth decade of life. MPS VI, or Maroteauz-Lamy syndrome, resembles Hurler syndrome. Onset is in infancy, however, intelligence is normal. Individuals may live into the second or third decade.

Individuals with MPS VII, Sly disease, experience corneal clouding, skeletal irregularities, and enlargement of the liver and spleen. Intellectual impairments vary for this type of MPS.

Is there any treatment?

What is the prognosis?

What research is being done?

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