An autosomal recessive neurodegenerative disorder caused by the absence or deficiency of beta-galactosidase. It is characterized by intralysosomal accumulation of G(M1) GANGLIOSIDE and oligosaccharides, primarily in neurons of the central nervous system. The infantile form is characterized by muscle hypotonia, poor psychomotor development, hirsutism, hepatosplenomegaly, and facial abnormalities. The juvenile form features hyperacusis; seizures; and psychomotor retardation. The adult form features progressive dementia; ataxia; and muscle spasticity. (From Menkes, Textbook of child neurology, 5th ed, pp96-7)