Cerebrotendinous xanthomatosis: need for early diagnosis

Cerebrotendinous xanthomatosis is a rare autosomal recessive lipid storage disease characterized by widespread tissue deposition of two neutral sterols, cholestanol and cholesterol, resulting in tendinous xanthomas, juvenile cataracts, progressive neurological defects and premature death from arteriosclerosis. The primary biochemical defect is deficiency of hepatic mitochondrial enzyme sterol-27-hydroxylase which catalyses the hydroxylation of cholestanol (5-alpha dehydro derivative of cholesterol) and this deficiency decreases bile acid synthesis. Substantial elevation of serum cholestanol and urinary bile alcohols with low to normal plasma cholesterol concentration establishes the diagnosis. Cerebrotendinous xanthomatosis is exceptionally rare in the Indian population. We are reporting a woman with this rare disorder, who was on antiepileptic and antipsychotic drugs for a prolonged period and whose original condition went undiagnosed. She presented with xanthomas on the Achilles tendons and the upper end of tibia. She was mentally subnormal and her serum cholestanol level was raised. Her younger sister too was severely affected by this disorder. Early treatment with chenodeoxycholic acid is known to prevent disease progression.