Questions and Answers About Tuberous Sclerosis
by
Vicky Holets Whittemore, Ph.D.
Vice President of Medical and Scientific Affairs, NTSA
 

Can I catch tuberous sclerosis from another person?

No you can not "catch" tuberous sclerosis from someone, but you can inherit it from your parent if they have the disorder. Tuberous sclerosis is an autosomal dominant genetic disorder which means if a parent has the tuberous sclerosis gene, each offspring of the person has a 50% chance of inheriting it.

Where is the gene for tuberous sclerosis?

There are actually two genes that can cause tuberous sclerosis. One of the genes (the TSC I gene) is located on chromosome 9 and is called the hamartin gene. The other gene (the TSC2 gene) 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 tuberous sclerosis.

Is there a genetic test (prenatal test) for tuberous sclerosis?

No, a genetic test for tuberous sclerosis is not yet available, Even though both of the TS genes have been located, it will take a couple more years of research to develop a genetic test for TSC. The researchers have to find out what changes in these genes actually cause tuberous sclerosis and refine their methods to pick out these gene defects.

How can so many different organs be affected by tuberous sclerosis?

Researchers speculate that the defect in the tuberous sclerosis genes causes problems in cells in many different organs because the genes are important for cell function very early in the life of the fetus. At the earliest stages there are only a few cells that make up the fetus. A defect in these early stages can lead to problems in many different organs.

What is the normal life expectancy of an individual with tuberous sclerosis?

Individuals with tuberous sclerosis can live long, productive lives and will die from the same filings everyone else does -- heart disease, cancer, strokes, etc. There can be complications from the disease in some organs such as the kidneys and brain that can lead to difficulties and even death, but with modern medical techniques, individuals with tuberous sclerosis can look forward to excellent health care and live long lives.

What is the average age at diagnosis of individuals with tuberous sclerosis?

This figure is not known. Sixty to eight percent of individuals will have seizures at some point in their life. Many individuals with tuberous sclerosis present to their doctor because they develop seizures, and will subsequently be diagnosed with tuberous sclerosis. Seizures can start at any time, from infancy to adulthood. Seizures in individuals with tuberous sclerosis are often intractable (do not respond to anti-epileptic drugs), so they will go through life having seizure after seizure every day. With new anti-epileptic drugs coming onto the market, and new advances in brain surgery for seizures, there is hope for all individuals with tuberous sclerosis.

Are the tumors that form in the brain, heart, kidneys and eyes cancerous?

Generally the tumors in the heart, brain and eyes are benign, but may cause problems. Research has shown that the kidney tumors are malignant in 7- 1 0% of individuals with TS. Tumors that grow in the brain can block the flow of cerebral spinal fluid in the spaces (ventricles) in the brain. This can lead to behavior changes, nausea, headaches or a number of other symptoms. In the heart, the tumors are usually at their largest at birth, and then decrease in size as the individual gets older. These heart tumors, called cardiac rhabdomyomas, can cause problems at birth if they are blocking the flow of blood, or causing severe arrhythmia problems. The tumors in the kidney (renal angiomyolipoma) can become so large as to eventually take over all of the normal kidney function. In the past, the patient was left until they developed kidney failure. Today, doctors are more aggressive and remove individual tumors before they get too large and compromise healthy kidney tissue. The tumors in the eyes are not as common, but can present problems if they grow and block too much of the retina.

Do researchers need more subjects for their studies?

Yes. The genetic researchers are in need of blood samples and tissue samples (taken either at the time of surgery or at the time of death) from individuals from families where more than one individual has been diagnosed with tuberous sclerosis, as well as from individuals who are a spontaneous mutation, or the first case in a family. The more samples they have to study, the sooner they will be able to develop a genetic test and learn what the TSC genes do. These findings would then lead to an improved understanding of what the genes normally do, and how new therapeutic treatments can be developed for those who have tuberous sclerosis.

Updated 8/97