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Health condition

Cerebrotendinous xanthomatosis

Cerebrotendinous xanthomatosis is that rarest of things - a treatable genetic neurodegenerative disease. Bile acid replacement halts it, making early recognition of its odd clue-set genuinely urgent.

Key points

What matters most, at a glance.

The essentials in plain English - symptoms, when to seek help, who to see and what treatment looks like.

  • Classic clues: childhood-onset chronic diarrhoea, juvenile cataracts, tendon lumps (especially Achilles), and neurological decline in adult life

  • Neurological features: cognitive decline or psychiatric change, spasticity, ataxia, neuropathy, seizures

  • Caused by CYP27A1 variants blocking bile acid synthesis; cholestanol accumulates in brain and tendons

  • Diagnosis: elevated plasma cholestanol, confirmed by genetic testing

  • Chenodeoxycholic acid treatment normalises the biochemistry and stabilises or improves the disease

  • Every year of diagnostic delay costs neurological ground that treatment cannot always reclaim

Understanding it

About Cerebrotendinous xanthomatosis, and what to do next.

CTX assembles its evidence across decades and specialties, which is precisely why it is missed: the infant with stubborn diarrhoea, the teenager needing cataract surgery, the young adult with thickened Achilles tendons, and the thirty-something with declining cognition, spastic gait or first psychosis are the same patient - but rarely does one clinician see the whole file. The biochemical fault is a blocked step in bile acid synthesis; cholestanol accumulates and deposits in tendon, lens and brain. Average diagnostic delay runs well over a decade in published series, a painful statistic for a disease with an effective oral treatment.

The screening test is a plasma cholestanol level - cheap and decisive when the pattern raises suspicion - with CYP27A1 sequencing confirming. Chenodeoxycholic acid replacement corrects the pathway, normalises cholestanol, and stabilises the neurology; started early, it can prevent the disease's expression almost entirely, and siblings identified by cascade testing may be spared it altogether. Practical rule of thumb worth spreading: juvenile cataracts plus chronic diarrhoea, or Achilles xanthomas in a person with normal cholesterol, should trigger the test. Care after diagnosis is shared between metabolic medicine and neurology, and family testing is offered as standard.

A quiet reminder

This guide is for information, not medical advice.

Your GP knows your history and can tell you which parts apply to you. If in doubt, see them.

Frequently asked

Common questions about Cerebrotendinous xanthomatosis.

Quick, plain-English answers to what people ask us most.

  • What is cerebrotendinous xanthomatosis?

    Cerebrotendinous xanthomatosis is a rare inherited metabolic disorder in which the body cannot properly break down cholesterol, leading to abnormal fat deposits building up in the brain, tendons, and other tissues over time. It typically causes a combination of neurological, tendon and other systemic symptoms that develop gradually from childhood into adulthood. Early diagnosis and treatment can meaningfully alter its course.

  • What causes this condition?

    It is caused by mutations in the CYP27A1 gene, which is needed for normal breakdown of cholesterol within cells. Without functioning enzyme, abnormal fatty substances (cholestanol and related compounds) accumulate in various tissues, particularly the brain, tendons and lens of the eye. It is inherited in an autosomal recessive pattern.

  • What symptoms does it cause?

    Symptoms can include chronic diarrhoea in infancy, cataracts developing in childhood, swellings over the tendons (particularly the Achilles tendon), and progressive neurological problems such as poor coordination, cognitive decline and psychiatric symptoms typically emerging in the teens or twenties. The combination and timing of these features can be an important diagnostic clue. Symptoms and progression vary between individuals.

  • Is it hereditary, and should family be tested?

    Yes, it is inherited in an autosomal recessive pattern, meaning both parents carry one altered copy of the gene without necessarily having symptoms themselves. Siblings of an affected individual have a chance of also being affected, and genetic counselling can clarify the risk and testing options for family members. Early identification in siblings allows treatment before significant symptoms develop.

  • Can this condition be treated?

    Yes, treatment with a bile acid called chenodeoxycholic acid can correct the underlying metabolic problem and, particularly when started early, can prevent or slow progression of neurological and other symptoms significantly. This makes early diagnosis especially important. Regular monitoring helps track response to treatment over time.

  • What happens if it isn't treated?

    Without treatment, the condition tends to progress, with worsening neurological symptoms, cataracts, and other complications developing over years. Early treatment, ideally started before significant neurological damage occurs, offers the best chance of preventing or limiting long-term disability. This underlines the importance of prompt diagnosis once suspected.

  • When should this be suspected and investigated?

    Consider assessment if there is a combination of early cataracts, tendon swellings, and progressive neurological or cognitive symptoms, particularly in a younger person. NHS metabolic or neurology referral can take several weeks; a private specialist consultation is typically available within about 2 weeks for earlier assessment and testing.