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An autosomal recessive inherited sphingolipidosis caused by a deficiency of GALACTOSYLCERAMIDASE leading to an accumulation of PSYCHOSINE in LYSOSOMES of the BRAIN; PERIPHERAL NERVES; LIVER; KIDNEY; and LEUKOCYTES. In the nervous sytem there is prominent central and peripheral demyelination. The infantile form presents at age 4-6 months with psychomotor retardation, MUSCLE SPASTICITY, and tonic spasms induced by minor stimuli. Death occurs within two years. Later onset forms of this disease are characterized by a less fulminant course. (From Menkes, Textbook of Child Neurology, 5th ed, pp195-7)