The GM1 gangliosidoses are caused by a deficiency of beta-galactosidase, with resulting abnormal storage of acidic lipid materials. GM1 has three forms: early infantile, late infantile, and adult.
Early infantile GM1 presents with onset shortly after birth including seizures, hepatosplenomegaly, coarsening of facial features, skeletal irregularities, joint stiffness, muscle weakness and exaggerated startle response to sound. Cherry-red spots in the eyes are common. Patients may be deaf and blind by age 1 and often die by age 3 from cardiac complications or pneumonia.
Late infantile GM1 typically presents between ages 1 and 3 years with ataxia and seizure. Onset of adult GM1 is between ages 3 and 30 with muscle atrophy, corneal clouding in some patients, and dystonia. Angiokeratomas may develop on the lower part of the trunk of the body. Most patients have a normal size liver and spleen.