Cerebrotendinous Xanthomatosis (CTX)
Cerebrotendinous xanthomatosis (CTX) is a rare condition that affects the body's ability to metabolize fats known as cholesterols. Patients with CTX are unable to break down different forms of cholesterol, which build up in certain areas of the body.
CTX is characterized by fatty yellow nodules (xanthomas) located in the connective tissues within the brain. These deposits can cause progressive damage to the brain and other areas of the body. Patients with CTX do not have elevated levels of cholesterol in their blood; however, they do have elevated levels in their tissues.
Symptoms of CTX vary depending on the age of the patient, and the severity of the condition.
For infants and children, symptoms may include:
- Chronic diarrhea during infancy
- Cataracts in late childhood
- Frequent bone fractures due to brittle bones
When a patient with CTX enters into adulthood, they may begin to notice the following neurological symptoms:
- Difficulty with coordination
- Difficulty with speech
The fatty deposits can also result in cardiovascular disease or stroke if they limit or block the blood flow to the heart or brain.
Causes and Risk Factors
Cerebrotendinous xanthomatosis is caused by a change in the CYP27A1 gene, which is involved in the production of an enzyme that breaks down cholesterol.
The condition is inherited, and both parents need to pass on the genetic abnormality in order for their child to have the condition. If the child only receives one copy of the abnormal gene then they are a carrier for CTX but will not have any symptoms.
The condition is rare and occurs in an estimated 3 to 5 out of every 100,000 people. The condition affects all genders and ethnicities; however, it is most common in the Moroccan Jewish population.
Diagnosis of CTX usually begins with a physical exam and a review of the patient's medical history and symptoms. During childhood, the condition can be diagnosed through urine analysis. In adults, a positive diagnosis of CTX is based on identifying at least two of the five main symptoms, including:
- Persistent diarrhea
- Cataracts at a young age
- Fatty deposits in the tendons
- Neurological abnormalities
- Abnormal amounts of cholesterol in the tendons of the body.
Imaging tests, such as magnetic resonance imaging (MRI), computed tomography (CT) or a cerebrovascular evaluation can help the medical team better understand what is going on inside the body. An MRI or CT scan can be used to look for areas of the brain that resemble stroke conditions and can help the medical team determine if neurological damage has occurred. A cerebrovascular evaluation will look at the affected blood vessels and may include an angiography.
Because the fatty deposits can cause cardiovascular disease, evaluation of the patient's cardiovascular health may also be conducted. A cardiovascular evaluation will look at the heart and blood vessels and may include additional imaging tests such as an echocardiography or angiography.
There is no cure for CTX, however, if the condition is treated early, its progression can be slowed or stopped.
The first treatment generally prescribed is chenodeoxycholic acid (CDCA) replacement therapy, which works to normalize the body's ability to break down cholesterol. Other medications, known as HMG-CoA reductase inhibitors, may be prescribed to help lower cholesterol levels by blocking the enzyme responsible for the production of cholesterol.
In CTX patients, cataract surgery also is often required by the age of 50.
For patients who have experienced a stroke, the Stroke Program at Cedars-Sinai provides a multidisciplinary treatment approach through a personalized treatment plan tailored to each patient. Patient care is generally broken down into three categories: stroke prevention, treatment immediately after a stroke, and post-stroke rehabilitation.