Diagnosis of spinal xanthomatosis by next-generation sequencing: identifying a rare, treatable mimic of hereditary spastic paraparesis.

Cerebrotendinous xanthomatosis is an autosomal recessive disorder of bile acid metabolism causing a range of progressive neurological symptoms. Even in the presence of the classical triad of neurological dysfunction, tendon xanthoma and early onset cataracts, the diagnosis is often missed. It can mimic more common conditions such as hereditary spastic paraparesis or multiple sclerosis, particularly if the phenotype is spinal xanthomatosis where the disease causes a spastic paraplegia. Early recognition and treatment with chenodeoxycholic acid may prevent irreversible neurological damage. The introduction of next-generation sequencing to screen for a large number of genetic disorders associated with progressive spastic paraparesis will allow earlier identification and treatment of these patients and their families, and will particularly help in atypical cases such as the patient described here.