What is Tuberous Sclerosis Complex (TSC)?

TSC is a complex genetic condition caused by an alteration in a gene. People with TSC have growths, sometimes called tubers or lesions in different organs of the body (brain, heart, eyes, skin, kidneys, lungs) and may have epilepsy, learning disabilities, autism spectrum disorder and kidney problems. Symptoms vary from one person to another with some people showing very few symptoms and others more severely affected.

How many people have TSC?

At least two children born each day will have TSC. Current estimates place TSC affected births at one in 6,000. Nearly 1 million people worldwide are known to have TSC, with approximately 8,000 people in the UK. There are many undiagnosed cases due to the obscurity of the disease and the mild form symptoms may take in some people.

How does a person develop TSC?

TSC is transmitted either through genetic inheritance or as a spontaneous genetic mutation (gene change). Children have a 50 percent chance of inheriting TSC if one of their parents has this condition. At this point, only one-third of TSC cases are known to be inherited. The other two-thirds are believed to be a result of spontaneous gene change. The cause of these spontaneous gene changes is still a mystery. See Genetics of TSC for more information.

If a parent has a mild form of TSC, will their child with TSC also be mildly affected?

People with mild cases of TSC can produce a child who is more severely affected. In fact, some people are so mildly affected that they may only find out they also have TSC after their more severely affected child receives a diagnosis of TSC.

How is TSC diagnosed?

Diagnosis of TSC is currently made after the following tests are preformed: a brain MRI or CT Scan, renal ultrasound, echocardiogram of the heart, EKG, eye exam and a Wood’s Lamp evaluation of the skin. See How TSC is diagnosed for more informaton.

What genes are responsible for TSC?

Two genes have been identified that can cause TSC. Only one of the genes needs to be affected for TSC to be present. The TSC1 gene is located on chromosome 9 and is called the hamartin gene. The other gene, TSC2, is located on chromosome 16 and is called the tuberin gene. Researchers are now trying to determine what these genes do and how a defect in these genes causes TSC.

How can so many different organs be affected by TSC?

Both the TSC1 and TSC2 genes are believed to suppress tumor growth in the body. When either of these genes are defective, tumors are not suppressed and TSC results. The genes also play a role in the early fetal development of the brain and skin.

Are the tumors cancerous?

The growths resulting from TSC are non-cancerous, but may still cause problems. Those that grow in the brain can block the flow of cerebral spinal fluid in the spaces (ventricles) in the brain. This can lead to behaviour changes, nausea, headaches or a number of other symptoms. In the heart, the growths are usually at their largest at birth, and then decrease in size as the individual gets older. These are called cardiac rhabdomyomas, and can cause problems at birth if they are blocking the flow of blood or causing severe arrhythmia problems. The growths in the eyes are not as common, but can present problems if they grow and block too much of the retina. Those in the kidney (renal angiomyolipoma) can become so large they eventually take over all of the normal kidney function. Very rarely (less than 2 percent of) individuals with TSC develop malignant (cancerous) kidney tumors. See How TSC affects the body for more information.

What is the normal life expectancy of an individual with TSC?

Most people with TSC will live a normal life span. There can be complications in some organs such as the kidneys and brain that can lead to severe difficulties and even death if left untreated. To reduce these dangers, people with TSC should be monitored throughout their life by their physician for potential complications. Thanks to research findings and improved medical therapies, people with tuberous sclerosis can expect improved health care.

Since there is no cure, what can be done?

Early intervention is helping to overcome developmental delays. Advancements in research are bringing new and improved therapeutic options. Surgery to remove growths or stop growth is helping to preserve the function of affected organs. Technology is pinpointing the exact portions of the brain stimulating seizures and creating new therapies to help control seizures. With every new day we are one step closer to finding improved treatments.

Page created by TSA staff and reviewed by Dr Chris Kingswood FRCP, Royal Sussex County Hospital, May 2008.
Thanks to the TSAlliance for the use of some of their material.