Definition:
Alpha-mannosidosis is caused by deficient activity of the enzyme alpha-D-mannosidase. As a result, sugar chains accumulate in lysosomes resulting in general cellular dysfunction. Alpha-Mannosidosis is classified into types I through III based on severity and age of onset.  In contrast to the usual classifications scheme of these disorders, type III is the most severe.

Symptoms:
Symptoms range widely in their onset and severity. The onset of the most severe form, Type III, begins within the first months of life and includes a quick progression of mental retardation, liver and spleen enlargement, hearing loss, respiratory infections and skeletal abnormalities. Often the appearance of an affected individual includes the following coarse facial features: protruding forehead, leveled nasal bridge, small nose and wide mouth. Muscular weakness or spinal abnormalities can occur due to the build up of storage materials in the muscle. A milder form of Alpha-mannosidosis involves mild to moderate mental retardation which develops during childhood or adolescence.

In sum, all symptoms of Alpha-mannosidosis are progressive. However, some research has demonstrated that symptoms stabilize during the second decade of life.

Diagnosis and Testing:
A diagnosis is made by measuring the enzymatic activity of alpha-D-mannosidase in white blood cells. If there is a decreased level of the enzyme in comparison to standard levels, a diagnosis can be made. It is thought that this disorder might be under diagnosed for a few different reasons — the diagnosis is often made late in the disease's progression, symptoms are often mild, or the biochemical diagnosis does not yield conclusive results.

Life Expectancy:
The life expectancy in Alpha-mannosidosis is highly variable. Individuals with early onset severe disease often do not survive beyond childhood, whereas those with milder disorders may survive well into adult life.

Treatment:
There is no cure for Alpha-Mannosidosis. Treatment is limited to reducing or controlling the symptoms of this disorder by, for example, taking medication to control seizures, using a hearing aid to assist with hearing loss, and by having routine physical therapy to assist with muscular pain and weakness. In some cases, a wheelchair is recommended if muscle or spinal impairments immobilize the individual affected. Bone marrow transplants performed at an early age have shown promise to halting the progression of this disorder.

Patient Groups:
International Society for Mannosidosis & Related Diseases
P.O. Box 328
Dexter, MI 48130
www.mannosidosis.org
tel: (734) 449-8222
fax: (734) 449-2282
Terri Klein, Executive Director
info@ismrd.org