Definition:
Beta-Mannosidosis results from deficient activity of the enzyme beta-mannosidase. This leads to accumulation of sugar chains (oligosaccharides) within the lysosomes.  This lysosomal accumulation leads to general cellular dysfunction, the manifestations of Beta-Mannosidosis.

Symptoms:
Beta-Mannosidosis does not display some of the hallmark features of Lysosomal Disease. Therefore, it is believed that the prevalence of this disorder has been under diagnosed. The most typical features of Beta-Mannosidosis are mental retardation, recurrent respiratory infections, hearing loss, and angiokeratomas.

Diagnosis and Testing:
To determine if the patient has Beta-Mannosidosis, a urine test is performed measuring increased levels of oligosaccharides, the type of sugar chains in the lysosome that accumulate as a result of the malfunctioning enzyme. A urine test is then routinely followed by a blood test or skin biopsy which will show reduced activity of the enzyme, beta-mannosidase. Prenatal screening is also available to examine beta-mannosidase activity in the fetus. Genetic testing is availble in combination with these diagnostic tests to look for the mutation that causes Beta-Mannosidosis.

Life Expectancy:
Life expectancy is highly variable in Beta-Mannosidosis. Many adults with this disorder have been recognized.

Treatment:
There is no cure for Beta-Mannosidosis. Treatment is limited to reducing or controlling the symptoms of this disorder, by, for example, making sure to keep respiratory infections at a minimum and to monitor hearing loss.