Onset takes place in late teens or early adult life with cerebellar dysfunction, visual problems, and coarsening of facial features.
Intellectual impairment is mild at first but intelligence tends to deteriorate in time.
Cherry red spots and retinitis pigmentosa. Accumulation of GM1 ganglioside in brain and beta-galactosidase in all tissues. The syndrome is familial and is transmitted as an autosomal recessive trait.