Alpha-mannosidosis is a rare metabolic disorder characterized by a deficiency of the lysosomal enzyme alpha- mannosidase. Due to this deficiency, oligosaccharides accumulate within cells of body tissues. Symptoms of the disorder vary widely, as does severity. There are two forms of alpha-mannosidosis. Type I typically develops in early childhood, with age of onset ranging from 6 months of age to 3 years. Type II develops in later childhood or adolescence, and symptoms are much less severe than those found in Type I. Approximately 60-80 cases of alpha-annosidosis have been reported.
One of several congenital lysosomal storage diseases in which the deficiency of α- mannosidase is associated with mental retardation, kyphosis, and accumulation of mannose in tissues. The disease, which is lethal, can be treated with bone marrow transplantation.