Musculoskeletal Disorders: Mucopolysaccharidoses

Description

Mucopolysaccharidoses (MPs) are severe genetic disorders in children and adults. They involve an abnormal storage of mucopolysaccharides (long molecular chains of sugar, used by the body in the building of connective tissues ), caused by the absence of a specific enzyme. Without the enzyme, the breakdown process of mucopolysaccharides is incomplete. Partially broken down mucopolysaccharides accumulate in the body's cells and tissues. The storage process affects the children's appearances, bodily functions and development. MPs children tend to look alike and to have very similar health problems. The MPs diseases are classified as lysosomal storage disorders .
All of the Mucopolysaccharidoses, except Hunter Syndrome (which has has an X-linked recessive mode of inheritance , which limits the syndrome to the male sex), have an autosomal recessive mode of inheritance .
Other similar diseases include Mucolipidoses , Oligosaccharidoses and Glycosphingolipidoses .

For a list of all MPs disorders and their common abbreviations, click here .

Symptoms and Signs

An MPs baby appears normal at birth and seems to develop normally for about the first year or more depending on which MPs type the child is affected with. The first signs can vary and are evident at different ages in affected children. Symptoms that usually prompt medical attention are ear infections, runny noses and colds.
The mucopolysaccharide storage disorders are progressive and vary widely in severity. All MPs children tend to have coarse facial features. All of them have, in some degree, skeletal involvement. In most children this involves joint changes with limitation of movement. In all of the MPs disorders, multiple organs are involved. Several children have clouding of the cornea which leads to vision impairment. Enlargement of the liver and spleen and involvement of the heart and blood vessels are frequent symptoms. Progressive mental retardation is present in some children, as well as umbilical and groin hernias, stunted growth, fluid on the brain, thickened skin, excessive hair growth, chronic runny nose, chronic ear infections causing hearing loss, and a projected life expectancy of ten to twenty years.

Diagnosis and Treatment

A doctor bases the diagnosis on the symptoms. Mucopolysaccharidoses can also be diagnosed before birth using amniocentesis or chorionic villus sampling , in which samples are removed and screened for abnormal enzyme activity. Following birth, the child's urine can be screened, which, along with blood and other tests, can identify the presence of excess mucopolysaccharides. X-rays can also be used to look for bone abnormalities.
No cures are currently available. Attempts at replacing the abnormal enzyme have had limited, temporary success. Bone marrow transplantation may produce some small improvements but often causes death or disability, and the treatment remains controversial.

The information in this page is presented in summarised form and has been taken from the following source(s):
1. The Canadian MPS Society: http://www.mpssociety.ca/