Mucopolysaccharidoses

What are Mucopolysaccharidoses?

The mucopolysaccharidoses are a group of inherited diseases in which a defective or missing enzyme causes large amounts of complex sugar molecules to accumulate in harmful amounts in the body's cells and tissues.  This accumulation causes permanent, progressive cellular damage that affects appearance, physical abilities, organ and system functioning, and, in most cases, mental development.   Depending on the type of mucopolysaccharidosis, affected individuals may have normal intellect or may be profoundly retarded, may experience developmental delay, or have severe behavioural problems. Physical symptoms generally include coarse or rough facial features, thick lips, an enlarged mouth and tongue, short stature with a disproportionately short trunk (dwarfism), abnormal bone size or shape (and other skeletal irregularities), thickened skin, enlarged organs such as the liver or spleen, hernias, and excessive body hair growth. 

Is there any treatment?

Currently there is no cure for these disease syndromes.  Medical care is directed at treating systemic conditions and improving the person's quality of life. Physical therapy and daily exercise may delay joint problems and improve the ability to move. Surgery to remove tonsils and adenoids may improve breathing among affected individuals with obstructive airway disorders and sleep apnoea.  Surgery can also correct hernias, help drain excessive cerebrospinal fluid from the brain, and free nerves and nerve roots compressed by skeletal and other abnormalities. Corneal transplants may improve vision among patients with significant corneal clouding.  Enzyme replacement therapy has proven useful in reducing non-neurological symptoms and pain. 

What is the prognosis?

The mucopolysaccharidoses syndromes share many clinical features but have varying degrees of severity.  Most individuals with a mucopolysaccharidosis syndrome generally experience a period of normal development followed by a decline in physical and mental function.  Longevity is dependent upon the particular syndrome.  For example, children with a form of mucopolysaccharidosis called Hurler syndrome often die before age 10 from obstructive airway disease, respiratory infections, or cardiac complications.  A child with the type known as Scheie syndrome can live into adulthood, while one with a mild case of the type known as Hunter syndrome may live into his or her 50s or beyond.