Alpha-mannosidosis is a rare autosomal recessive lysosomal-storage disorder resulting from deficiency of lysosomal alpha-mannosidase activity. The disease shows a wide range of clinical phenotypes caused by intracellular accumulation of mannose-containing oligosaccharides, which ultimately may lead to mental retardation, hearing loss, skeletal changes and immune deficiency. Lysosomal alpha-mannosidase ...