Mannosidosis is a highly variable multisystem disorder. Onset may be in infancy but in other patients symptoms appear later in the first decade. Progression of disease is more rapid in individuals with early onset (type 3) with rapid mental, motor deterioration and early death. The characteristic coarse facial features usually are evident later in milder cases (types 1 and 2) that have mild or moderate intellectual disabilities. Regardless, mannosidosis is relentlessly progressive with mental deterioration and motor disabilities. Ataxia is a common feature. Dental anomalies (diastema), large ears, macroglossia, joint stiffness,, hepatosplenomegaly, enlarged head circumference, hearing loss (sensorineural), increased susceptibility to infections, dysarthria, and spondylolysis may be present.
