A lipid storage disease, inherited as an autosomal recessive trait, characterized by xanthomas of the tendons, the white matter of the brain, and the lungs, and by spasticity, ataxia, pyramidal paresis, mental retardation, dementia, early cataracts, and atherosclerosis. It is associated with elevated plasma and tissue levels of cholestanol and defective bile synthesis, with the deposition of cholestanol in the central nervous system and myelin of peripheral nerves. The lesions contain cholesterol and dehydrocholesterol. (Dorland, 28th ed)