An inborn error of carbohydrate metabolism manifesting as a genetic multisystem disorder of autosomal recessive inheritance. A predominant feature is severe central and peripheral nervous system involvement resulting in psychomotor retardation, seizures, cerebellar ataxia, and other symptoms which include growth retardation, retinitis pigmentosa, hypothyroidism, and fatty liver. The notable biochemical feature is the deficiency of a large number of blood glycoproteins and decreased activities of various blood coagulation factors.