Tuberous Sclerosis Complex, or TSC, is a genetic disease, so it is not contagious. It is a mutation of a tumor suppressor gene that disables the suppressor protein. This causes benign tumors to form in the brain and can also cause tumors in the lungs, heart, kidneys, eyes, and skin, to name a few. There is a wide range of symptoms, the most common being seizures and mental handicaps. It is referred to as either TS or TSC, the latter to discern it from Tourette's syndrome.

Current statistics for the disease show that approximately 1 in 6,000 live births are affected, or about 50,000 people in the U.S. and 1,000,000 people worldwide; only 1/3 of the cases are inherited: the other 2/3 are spontaneous mutations. Gender, race, and ethnicity do not affect the occurrence of TSC.

Currently there are no cures for the disease, and no way to predict the severity and the age at which the symptoms will appear.