What Is Tuberous Sclerosis Complex (TSC)?
Tuberous sclerosis complex is a rare genetic disorder distinguished by one defining feature: cells in the body grow and divide too actively. This condition causes abnormal but benign tissue growths to develop in multiple organs, including the brain, skin, heart, kidneys, and lungs. These growths may resemble tumors, and depending on their location and number, they can affect the body in very different ways.
TSC most commonly leads to benign tumors such as facial angiofibromas (Figure 1), and it may also cause hypopigmented skin patches (Figure 2). While some individuals experience only mild symptoms, others require lifelong medical care. TSC is therefore a condition with highly variable clinical presentations.
Figure 1. Facial Angiofibromas
Figure 2. Hypopigmented Skin Patches
Where Does the Disease Begin?
In a healthy body, cell growth is regulated by built-in “braking” mechanisms. In individuals with TSC, this braking system fails. More specifically, mutations in the TSC1 and TSC2 genes disrupt normal growth control. TSC1 and TSC2 are tumor suppressor genes that function to halt cell growth. When these genes malfunction (Figure 3), cells continuously receive signals to keep growing, leading to the formation of abnormal tissue growths in different parts of the body. These changes often begin before birth, even though they may not immediately affect organ function.
Figure 3. Mutation of TSC1 and TSC2 gene
Figure 4. Impact Area of TSC
Where Else Does TSC Have an Impact Besides the Skin?
Beyond the skin, TSC can also affect the nervous system and commonly leads to seizures, which are often the first symptom of the condition. In children, a frequent form of seizure associated with TSC is infantile spasms. In addition to seizures, TSC may cause developmental delays and impair cognitive and learning abilities. TSC is a multisystem rare disease, and other organs—including the brain, eyes, heart, kidneys, and lungs—may also be affected (Figure 4).