 Tuberous sclerosis complex TSC is a genetic disorder that causes non-malignant tumors to form in many different organs, primarily in the brain, eyes, heart, kidney, skin and lungs. The aspects of TSC that most strongly impact quality of life are generally associated with the brain: seizures, developmental delay, intellectual disability and autism. However, many people with TSC are living independent, healthy lives and enjoying challenging professions such as doctors, lawyers, educators and researchers. The incidence and severity of the various aspects of TSC can vary widely between individuals even between identical twins. Because TSC can manifest in so many different ways, diagnosis is generally made when physicians identify any two major features of TSC in one individual. One major feature is cardiac rhabdomyoma, an abnormal growth in the heart muscle generally found in young children and sometimes found by ultrasound examination during pregnancy. Other major features include specific abnormal skin growths or skin pigmentation, specific non-malignant tumors or growths such as subependymal nodules or subependymal giant cell astrocytomas SEGAs in the brain, lymphangioleiomyomatosis LAM in the lungs, angiomyolipomas in the kidneys, and tubers in the brain or hamartomas in the eye. Also, there are other minor features of TSC that might be diagnostic if found with a major feature in the same person. TSC can also be diagnosed by genetic testing described below. Major advancements in treatments such as these require clinical studies to test the effectiveness of experimental drugs, surgery, or other interventions in people with TSC. Because the TSC community is in vital need of new treatments, individuals with TSC frequently volunteer to participate in cutting-edge clinical studies. Some ongoing clinical studies in TSC include testing the effects of drug treatment on neurocognitive function, testing a new combination drug treatment for LAM, finding biomarkers to identify infants at high risk of developing autism or infantile spasms, and testing a topical drug treatment of facial angiofibromas. Thanks to volunteers in these and other studies, every new day brings us one step closer to finding improved treatments for TSC. 