In the infantile form there is increasing neurological
impairment, with progressive hypotonia, spasticity, no voluntary movements,
symmetric hyperreflexia, profound psychomotor retardation, and
seizures by the age of 3 to 4 years. Other clinical features include ophthalmologic
manifestations: bilateral optic atrophy, cortical blindness, nystagmus, and
strabismus. Severe respiratory infections occur.