From: Alpha-mannosidosis
Type II: Less severe, late onset form involving hearing loss, coarse face, mental retardation, and hepatosplenomegaly. | Type I: Severe infantile form which is fatal at <3–8 years of age. |  |
Type 1: Mild form clinically, recognized after 10 years of age, without skeletal abnormalities and very slow progression. | Type 2: Moderate form, clinically recognized before 10 years of age, with skeletal abnormalities, and slow progression with development of ataxia at age 20–30. | Type 3: Severe form, immediately recognized, with skeletal abnormalities, and obvious progression, leading to an early death from primary CNS involvement or myopathy. |