What is CTX?

Disease Information

Cerebrotendinous Xanthomatosis

Cerebrotendinous Xanthomatosis (CTX) is a rare, genetic disorder characterized by abnormal storage of fats (lipids) in many areas of the body (lipid storage disease).[1] People with this disorder cannot break down certain lipids effectively so fats such as cholesterol and a related lipid cholestanol, form fatty yellow nodules called xanthomas, that accumulate in the body, especially in the brain and the tendons that attach muscle to bone, which is reflected in the condition name (cerebro- meaning brain and -tendinous referring to tendons). CTX is caused by deleterious variants in the CYP27A1 gene. Treatment may involve taking the medication chenodeoxycholic acid (CDCA), or rarely other medications or interventions.

SueandEricStewart
Sue and Eric Stewart
Duane after Chenodal June 2019
Duane Huard celebrates his 34th birthday.

What causes Cerebroteninous Xanthomatosis (CTX)?

CTX is caused by deleterious variants in a gene called CYP27A1, which produces an enzyme called sterol 27-hydroxylase. Sterol 27-hydroxylase is required to convert cholesterol into bile acids, which are important in the absorption of fats in the intestine.  Specifically, production by the body of an important bile acid called chenodeoxycholic acid is impaired in CTX due to lack of functioning sterol-27-hydrolylase. In addition, when sterol 27-hydroxylase is not functioning properly to produce chenodeoxycholic acid, toxic lipid intermediates accumulate in the blood, body tissues, and the brain.

A compound called cholestanol, which is related to cholesterol, is produced in CTX, as well as compounds called bile alcohols. Cholestanol and bile alcohols are increased in the blood, while blood cholesterol levels are typically normal in affected individuals. Cholestanol accumulates in various tissues in the body, including the brain. Cholestanol makes up much of the fats found in xanthomas. The accumulation of cholestanol and other related compounds throughout the body’s tissues causes the signs and symptoms of CTX.

What are the Symptoms of CTX?

Signs and symptoms may include diarrhea, clouding of the lens of the eyes (cataracts), abnormal tendon growths, and neurologic problems that can be progressive, such as epilepsy, movement disorders, impaired speech (dysarthria), loss of sensation in the arms and legs (peripheral neuropathy), autism, dementia, and depression. Brittle bones that are prone to fracture (osteoporosis) is another sign of CTX. Signs and/or symptoms may appear:

In infancy and early childhood:

  • Liver Disease
  • Chronic Diarrhea
  • Cataracts
  • Cognitive Impairment
  • Autism
  • Impaired balance
  • Movement disorders

In adolescence and adulthood:

  • Xanthomas: Skin lesions characterized by accumulations of lipid-laden cells.  Involves abnormal tendon growth. 
  • Spasticity
  • Cerebellar signs such as intention tremor (tremulousness, shakiness when trying to move a limb), difficulty with fast hand movements, nystagmus (eyes moving back and forth), and truncal ataxia (balance problems)
  • Neurologic dysfunction with variable time of onset (seizures, balance problems, difficulty walking, movement disorders, spasticity (rigidity), impaired speech, and decreased sensation in arms and legs)
  • Cataracts
  • Coronary artery disease
  • Chronic diarrhea
  • Osteoporosis/Increased risk of bone fracture
  • Psychiatric symptoms, including behavioral changes, hallucinations, agitation, aggression

 

Other Clinical Names for Cerebrotendinous Xanthomatosis

  • cerebral cholesterinosis
  • cerebrotendinous cholesterinosis
  • cholestanol storage disease
  • cholestanolosis
  • CTX
  • Van Bogaert-Scherer-Epstein disease
  • sterol 27-hydroxylase deficiency

 

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