Alpha-mannosidosis, adult form is a rare, inherited disorder caused by a deficiency of the enzyme alpha-mannosidase. This enzyme is responsible for breaking down certain complex sugars in the body. When the enzyme is deficient, these sugars accumulate in the body, leading to a variety of symptoms. Symptoms of alpha-mannosidosis, adult form can include hearing loss, vision problems, skeletal abnormalities, mental retardation, and progressive neurological deterioration. There is no cure for alpha-mannosidosis, adult form, but treatment can help manage symptoms and slow the progression of the disorder.