What is cerebrotendinous xanthomatosis (CTX)?
Cerebrotendinous xanthomatosis (suh-ree-bro-ten-din-us zan-tho-ma-toe-sis), or CTX, is a rare genetic disorder.
Patients with this rare genetic disorder have an impaired ability to metabolize, or convert, fats known as cholesterols. In other words, patients are unable to break down different forms of cholesterol, which build up in certain areas of the body.
CTX can cause many symptoms, such as early cataracts in both eyes, neurological problems, tendon xanthomas (noncancerous fatty tumors on the tendons), cholestasis (which may be seen as jaundice in infants), and/or frequent diarrhea.
But not every person with CTX will have all the signs and symptoms. People with CTX usually have different symptoms and combinations of symptoms. They also get these symptoms at different ages so no person with CTX will look exactly like another. This all can make diagnosing CTX a challenge for healthcare professionals.
Early
Cataracts in Both Eyes
Neurological Deterioration/ Movement Disorders
Tendon Xanthomas
Neonatal Cholestasis/ Prolonged Jaundice
Chronic Diarrhea
Let’s take a closer look at how symptoms of CTX are caused…
CTX is a disorder of lipid (or fat) storage. With CTX, a certain protein (called an enzyme) in the body is not working properly. When this happens in people with CTX, the body does not break down cholesterol properly, which usually causes problems with fat, or lipid, metabolism.
- Lipid metabolism is a process your body uses to make energy from the food you eat, specifically from fats and cholesterol.
- This process requires chemicals in your digestive system (enzymes) to break down fats and cholesterol into different parts for energy.
- When these chemicals break down fats and cholesterol from food, your body can use the energy right away, or it can be stored in your body’s tissues.
So, what happens when cholesterol does not break down in patients with CTX?
- Toxins called cholestanols and bile alcohols stay in the body and build up in blood and tissues throughout the body over time.
- The build-up of these toxins can take years and happens in different parts of the body, which may cause different symptoms to appear that may vary from person to person.
- The toxins can build up in the eyes, tendons (tissues that connect muscle to the bone), brain, and other tissues over time, and can cause a number of different problems.
- These symptoms may get worse without treatment.
- Serious long-term health problems can happen over time.
- Talk to your doctors about all of your symptoms.
- Because CTX affects many different parts of the body, people with CTX may see different physician specialists.
- These various doctors may not realize, or be aware, that the different symptoms are connected until the disorder has caused serious problems.
Why does someone get CTX?
Because CTX is a genetic disorder, people with CTX are born with it. In other words, CTX is an inherited disorder, which means the cause of CTX can be traced back to your DNA, or genes. Your genes are passed down by your parents before your birth.
CTX is caused by autosomal recessive mutations in your genes.
- This means one copy of the damaged gene responsible for CTX was passed down by each parent, for a total of 2 damaged genes.
- Some people are also carriers of CTX but not affected with CTX. If only one copy of the gene responsible for CTX is passed down (one parent passes down a damaged gene while the other passes down a normal gene), the person who inherited the one damaged gene is not affected.
Because CTX can run in families, it is important to consider genetic counseling for the whole family if one person is diagnosed with the disorder.
Adapted from U.S. National Library of Medicine. Medline Plus. National Library of Medicine.
https://medlineplus.gov/genetics/understanding/inheritance/riskassessment/
If you or a loved one could have CTX, talk to your doctor about getting a diagnosis. Mirum offers 2 different no-cost genetic panels* that can help confirm a CTX diagnosis. Your doctor can decide which panel is most appropriate.
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