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What is tuberous sclerosis complex?

Tuberous sclerosis complex (TSC) is a rare genetic condition that causes tumors to grow in many different organs of the body. Tumors grow most often in the brain, skin, heart, eyes, kidneys, and lungs. Almost all of these tumors are benign (not cancerous), but they can cause a variety of health problems.

The symptoms of TSC usually appear before a child is 6 months old. The severity of the condition can vary widely — in some children the disease is very mild, while other children may have life-threatening complications.

Tuberous Sclerosis Complex (TSC) | Symptoms & Causes

What are the symptoms of tuberous sclerosis complex?

The symptoms of tuberous sclerosis complex (TSC) vary greatly from one child to the next, depending on what parts of the body are affected. In some children, the disease involves severe health problems that present early on in life, while other children may have such mild symptoms that they aren’t diagnosed with TSC until much later in life. Each individual will experience symptoms of TSC at different times throughout their life.

Common symptoms may include:

  • Heart tumors. About 50 percent of people with TSC have non-cancerous tumors in the heart, called rhabdomyomas. Most rhabdomyomas do not grow, and either get smaller or stay the same size. In some cases, a baby may be diagnosed with TSC before birth if these heart tumors are found on a fetal echocardiogram. Babies with more than one rhabdomyoma have a higher likelihood of being diagnosed with TSC.
  • Skin lesions. One of the earliest signs of tuberous sclerosis is white skin patches on a baby’s body, called hypomelanotic macules. As the child gets older, he or she may develop other lesions such as a rash across the cheeks and nose, areas of thickened skin, and small bumps under the fingernails or toenails.
  • Brain tumors. Children with TSC may also have one or more types of tumor in the brain. The most common are cortical tubers, subependymal giant cell astrocytomas (SEGAs), and subependymal nodules. Although some children may not have any of these tumors, most children with TSC will have at least one.
  • Seizures. About 85 percent of children with TSC have epilepsy caused by brain tumors. Babies often have a type of seizure called infantile spasms, which involve brief, repetitive muscle contractions and movements in the head, trunk, arms, and legs. These seizures can look like colic or an abdominal problem. Older children and adults may have other types of seizures including generalized, complex partial, and other focal seizures. More than 50 percent of those who have epilepsy have seizures that do not respond to standard medication.
  • Kidney lesions. Over 80 percent of people with TSC have some type of kidney (renal) lesion. The three most common are renal cysts, renal angiomyolipomas, and renal carcinomas. Renal angiomyolipomas are the most common, occurring in more than 80 percent of TSC patients. About 50 percent of people with TSC have renal cysts, which are generally benign, fluid-filled “holes” on the kidney. Cysts can sometimes cause increased blood pressure, and if the kidney becomes filled with cysts, it can cause problems with kidney function. Renal carcinoma, a cancerous growth on the kidney, is the least common type of kidney lesion.
  • Eye lesions. Some children with TSC have lesions on the retina or optic nerve called hamartomas. Most of these lesions stay dormant, and don't usually result in a loss of vision. White patches, or retinal pigmentary disturbances, sometimes appear on the retina, iris, or eyelashes. These white patches aren't harmful and don't require treatment.

What are the causes of tuberous sclerosis complex?

Tuberous sclerosis is an autosomal dominant genetic condition that is caused by a change (pathogenic variant) in either the TSC1 or TSC2 gene. This means:

  • Girls and boys have an equal risk of having the condition.
  • A change in only one copy of a gene causes TSC. A child can inherit the condition if either parent has it.
  • People with tuberous sclerosis have a 50 percent chance of passing the condition to their children.

About one-third of children with TSC inherited the genetic condition from a parent. However, for the other two-thirds of children with TSC, the condition is "spontaneous," meaning that the DNA change is the first instance of that change in the child's family.

Sometimes it is found that a child with TSC has a parent who also has the condition but didn’t know it. If your child is diagnosed with TSC, you may want to have genetic testing done to find out if you have it as well.

If you have one child with TSC, there is an increased chance that your other children will also have the condition.

Tuberous Sclerosis Complex (TSC) | Diagnosis & Treatments

How is tuberous sclerosis complex diagnosed?

Tuberous sclerosis complex (TSC) can cause a wide variety of symptoms. Many of them, such as seizures and developmental delays, are common in children who do not have TSC. Therefore, in order to diagnose the condition, doctors look for a group of symptoms. Some of the symptoms are present at birth, such as tumors on the heart and white patches on the skin.

Your child’s medical team may run a number of different tests to diagnose TSC, including:

  • magnetic resonance imaging (MRI) of the brain to look for tumors in the brain and renal system that often occur in children with TSC
  • echocardiogram (an ultrasound of the heart) to look for tumors on the heart
  • ultrasound to identify any kidney lesions
  • genetic testing to look for a TSC-related gene change. About 20 percent of people who have TSC do not have an identifiable gene change. Therefore a negative genetic test result cannot rule out a child having the condition.

Prenatal diagnosis

Sometimes heart tumors are seen during a routine prenatal ultrasound. These heart tumors can be an early sign of TSC. If your clinician sees this type of tumor, he or she may refer you for advanced ultrasound screening.

What are the treatment options for tuberous sclerosis complex?

Unfortunately, there is no cure for tuberous sclerosis complex yet. But there are many effective treatment options for most symptoms.

  • Antiepileptic medications can help treat and control infantile spasms and other types of seizures associated with TSC.
  • Laser surgery and topical creams can reduce the appearance of some of the skin lesions associated with TSC. This is especially true for facial lesions. Treating the lesions early, while they are still small, can make them easier to manage.
  • Surgical procedures are sometimes necessary to remove tumors and help preserve the function of affected organs.
  • Many behavioral therapies and educational approaches can be effective for children with developmental disorders, such as autism spectrum disorders.

Many of the complications of TSC can be managed more effectively if they are treated early. Early diagnosis, behavioral therapy, and alternative educational approaches can be very helpful to children with developmental disorders. Therefore, it is important to monitor your child closely for any symptoms related to TSC.

How we care for tuberous sclerosis complex

The Boston Children’s Hospital Multidisciplinary Tuberous Sclerosis Complex Program brings together pediatric specialists from epilepsy, neurosurgery, psychiatry, psychology, cardiology, nephrology, ophthalmology, dermatology, and genetics. Each member of our team has special expertise in treating children with TSC.

Our team consists of experts in many of the specialized fields related to TSC who all have experience providing care to children with complex conditions and their family members. Together, with our knowledge and background, we believe we can provide the best possible care for your child.

Tuberous Sclerosis Complex (TSC) | Frequently Asked Questions

How common is tuberous sclerosis complex?

It is estimated that about 50,000 people in the United States and 1 million worldwide have TSC. About one in 6,000 children are born with the disease each year.

How can one condition cause so many different complications?

TSC is caused by a change (pathogenic variant) in either the TSC1 or TSC2 gene. Scientists believe that these genes work together to suppress abnormal growth of cells. When a copy of one of the genes is altered, tumors and other abnormal tissues can grow in a number of different organs. Researchers have found that these genes also affect how brain cells grow, migrate, and connect with each other, which may be why children with the condition may have developmental and behavioral difficulties and seizures.

What is the long-term outlook for a child with TSC?

Most children with TSC live active, productive lives and have a normal life expectancy. Many of the complications associated with TSC can be managed effectively if caught and treated early. This makes it important for your child to be followed by a physician throughout his or her life.

Will my child have developmental problems or an intellectual disability?

There’s no simple answer, since each child is affected very differently by TSC. Many children do have some type of developmental delay, learning disability, or behavioral problems. Autism spectrum disorder is one of the most common developmental disorders seen in children with TSC, affecting about 50 percent of patients.

Early diagnosis and therapy can be very helpful to children with developmental difficulties. Therefore, your child’s medical team will watch his or her development closely. Talk with your doctor if you have any concerns about your child’s development or behavior.

How will this condition affect my child as an adult?

TSC can affect people in different ways at different times in their lives. Some of the symptoms may get better as your child grows. For example, epilepsy often resolves or is well-controlled, and heart tumors usually shrink or disappear completely as children get older. However, kidney or brain tumors can often grow into adulthood and they can sometimes cause serious problems that require treatment. TSC can affect individuals at any point in their lives, which makes it important for your child to be monitored closely throughout his or her life.

Tuberous Sclerosis Complex (TSC) | Programs & Services