What is Tuberous Sclerosis Complex?

Tuberous Sclerosis Complex (TSC) is a genetic condition that causes non-cancerous (benign) growths in various parts of the body, including the kidneys, brain and heart. It can affect people in different ways.

It is thought that there are between 4,000 and 11,000 people with TSC in the UK, and around 2 million people around the world. It is present from birth, although symptoms may not develop until early adulthood. Males and females, and people of all ethnicities are affected equally.

What are the signs and symptoms of TSC?

Some people with TSC have very mild symptoms, whereas others are more severely affected. Common symptoms include:

• seizures/epilepsy – this usually starts in childhood. The seizures may disappear or become less frequent with age
• learning difficulties – this can include poor memory and attention span, and difficulty making plans or organising actions
• behaviour difficulties – this can include impulsive behaviour, aggression, and self-harm
• skin lesions – patches or small lumps on the skin
• breathing difficulties
• high blood pressure
• sudden severe abdominal pain
• blood in the urine (haematuria) – caused by internal bleeding

TSC and the kidneys

Sometimes, the kidneys in TSC patients can develop fluid-filled pockets called cysts, that can affect kidney function.

TSC can cause high blood pressure, which can damage the delicate blood vessels in the kidneys. This can affect their function and may eventually lead to chronic kidney disease (CKD).

TSC can also cause non-cancerous growths in the kidneys, called angiomyolipomas (AMLs), which can bleed if they grow too large.

1 in 100 people with TSC-associated CKD will develop kidney failure and need dialysis or a kidney transplant.

Very rarely, kidney lesions in TSC patients can become cancerous and require close monitoring or a biopsy (tissue sample) to help decide on the appropriate treatment.

What causes TSC?

TSC is a genetic condition, caused by pathogenic (disease-causing) abnormalities in one of two genes – TSC1 or TSC2. These genes control cell growth through the activation of a molecular ‘switch’ called mTOR. Pathogenic abnormalities in these genes cause increased levels of mTOR, which leads to excessive growth and tumours in different parts of the body. The growths affect how well the organs work and may eventually lead to long-term damage.

How is TSC diagnosed?

TSC is diagnosed by a physical examination and imaging scans. These may include ultrasounds, magnetic resonance imaging (MRI) or computed tomography (CT) scans of the brain, chest and abdomen.

An echocardiogram (echo) and electrocardiogram (ECG) may be used to check for any issues with the heart.

Genetic testing may also be used to help make a diagnosis.

TSC can cause non-cancerous tumours to develop throughout the body. As well as the kidneys, the most common parts of the body to be affected are the:

• brain
• eyes
• teeth
• lungs
• heart
• liver
• pancreas
• skin

Skin abnormalities are common and can include areas of different-coloured or thick skin or raised red spots on the face that can look like acne (facial angiofibromas).

Most people with TSC have difficulties associated with their development, mental health and/or learning abilities. These can include autism, attention deficit hyperactivity disorder (ADHD), anxiety or depression. These are known as TSC-Associated Neuropsychiatric Disorders (TAND).

Does TSC run in families?

Around three in four cases of TSC occur without any previous family history, although it can still be passed on to the next generation.

In one in four cases, the condition has been inherited from a parent. This occurs in a pattern known as autosomal dominant inheritance:

Everybody has two copies of the two known TSC genes, one from each parent. One copy of a faulty gene is enough to cause the condition. There is therefore a one in two chance that a child born to an affected person will receive the abnormal gene, and develop TSC themselves, although the extent to which it affects them could be very mild, or more severe.

How is TSC treated?

There is currently no direct cure for TSC, so treatment focuses on managing symptoms, and preventing complications.

Blood pressure medication can help prevent damage to the delicate blood vessels in the kidney.

Lifestyle measures including keeping well-hydrated, staying active and following a low-salt diet can help to slow or prevent progression of TSC-associated CKD.

The growths caused by TSC are not infectious, and the vast majority (95 out of 100) are not cancerous. Whilst some growths can shrink and disappear by themselves, others may need medications such as mTOR inhibitors to help switch off the mTOR signal. In rare cases, the growths may need to be surgically removed or embolised - have their blood supply cut off.

Epilepsy can usually be treated with medication. If this is not effective, an implantable stimulator may help to reduce the severity of the seizures, or surgery may be needed to remove any tumours in the brain that are causing the seizures.

Children with TSC may need additional support at school.

mTOR inhibitor medication or laser therapy, may be prescribed to treat skin abnormalities. High SPF (sun protection factor) sunscreen should also be worn, even in dull weather.

Some people with TSC have very few symptoms and can live normal, healthy lives. However, others will need long-term care and support.

Where can I get more information or support about TSC?

For more information on tuberous sclerosis including its diagnosis, symptoms and treatment, visit The Tuberous Sclerosis Association.

Publication date: 09/2026

Review date: 09/2029