What is Tuberous Sclerosis Complex (TSC)?

Tuberous sclerosis complex (TSC) is a genetic disorder that causes tumors to form in many different organs, primarily in the brain, eyes, heart, kidney, skin and lungs. You will see it referred to both as tuberous sclerosis (TS) and tuberous sclerosis complex (TSC). The term TSC is used in scientific literature to distinguish tuberous sclerosis complex from Tourettes syndrome.

The disease affects some people severely, while others are so mildly affected that it often goes undiagnosed. Some people with TSC experience developmental delays, mental retardation epilepsy, autism and learning and behavioral problems. However, there are also many people with TSC living independent, healthy lives who enjoy challenging professions such as doctors, lawyers, educators and researchers.

TSC is the leading known genetic cause of epilepsy, and one of the leading known genetic causes of autism. At least two children born each day in the United States will have TSC (approximately 1 out of 6,000 live births).

TSC is transmitted either through genetic inheritance or as a spontaneous genetic mutation. 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 mutation. The cause of these mutations is still a mystery.

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.

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 Woods Lamp evaluation of the skin.

Two genes have been identified that can cause tuberous sclerosis complex. 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 tuberous sclerosis complex.

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 tuberous sclerosis complex results. The genes also play a role in the early fetal development of the brain and skin.

TSC knows no racial, cultural or economic barriers.

Currently, there is no cure.