Tuberous sclerosis

Overview

Tuberous sclerosis (TOO-bur-us skluh-ROH-sis), also called tuberous sclerosis complex (TSC), is an uncommon genetic disorder that causes tumors to develop in many parts of the body. These tumors are not cancer. Noncancerous tumors, also called benign tumors, are overgrowths of cells and tissue that are not expected. Symptoms vary widely, depending on where the growths develop and how big they get.

Tuberous sclerosis is often first found during infancy or childhood. Sometimes tuberous sclerosis can have such mild symptoms that the condition isn't diagnosed until adulthood, or it's not diagnosed at all. Sometimes tuberous sclerosis causes serious disabilities.

There is no cure for tuberous sclerosis, and the course of the disorder and how bad it gets can't be predicted. But treatments are available to manage symptoms.

Symptoms

Tuberous sclerosis symptoms are caused by noncancerous growths in parts of the body, most commonly in the skin, brain, eyes, kidneys, heart and lungs. But any part of the body can be affected. Symptoms can range from mild to severe, depending on the size or location of the growths.

Although symptoms are different for each person with tuberous sclerosis, they can include:

• Skin changes. Skin changes are most common. These include patches of lighter skin and small areas of thickened, smooth or bumpy skin. On the forehead, skin can have raised, discolored areas. Small soft bumps under or around the nails may occur. Growths on the face that start in childhood and look like acne are common.
• Seizures. Growths in the brain may be linked with seizures. A seizure is often the first symptom of tuberous sclerosis. In small children, a common type of seizure called infantile spasm involves stiffening of the arms and legs and arching the back and head.
• Problems in thinking, reasoning and learning. Tuberous sclerosis can result in developmental delays. Sometimes it limits the ability to think, reason and learn. Mental health conditions, such as autism spectrum disorder or attention-deficit/hyperactivity disorder (ADHD), also can occur.
• Behavior problems. Common behavior problems may include hyperactivity, self-injury or aggression, or issues with social and emotional adjustment.
• Kidney problems. Growths on the kidneys are common, and more growths may develop with age.
• Heart issues. Growths in the heart, if present, are usually largest at birth and shrink as a child gets older.
• Lung problems. Growths that develop in the lungs may cause coughing or trouble breathing, especially with physical activity or exercise. These lung tumors occur more often in females than in males.
• Eye problems. Growths can appear as white patches on the light-sensitive tissue at the back of the eye called the retina. These growths usually don't interfere with vision.
• Dental changes. Teeth may have pits in the surface. Small growths may appear on the gums, inside of the cheeks and on the tongue.

When to see a doctor

Symptoms of tuberous sclerosis may be noticed at birth. Or the first symptoms may appear during childhood or even years later in adulthood.

Contact your child's health care provider if you're concerned about your child's development or you notice any symptoms of tuberous sclerosis.

Causes

Tuberous sclerosis is a genetic disorder caused by gene changes — sometimes called mutations — in either the TSC1 or the TSC2 gene. These genes are thought to prevent cells from growing too fast or in an out-of-control way. Changes in either of these genes can cause cells to grow and divide more than needed. This leads to multiple growths throughout the body. These growths are considered noncancerous tumors.

Risk factors

Tuberous sclerosis can be the result of either:

• A random cell division error. About two-thirds of people who have tuberous sclerosis have a new change in either the TSC1 or the TSC2 gene linked with tuberous sclerosis. Most people do not have a family history of tuberous sclerosis.
• A gene change passed down in families. About one-third of people who have tuberous sclerosis get a changed TSC1 or TSC2 gene from a parent who has the disorder.

If you have tuberous sclerosis, you have up to a 50% chance of passing the changed gene and the disorder to your biological children, which means children related to you by blood may inherit that gene. How bad the disorder gets may vary. A parent with tuberous sclerosis may have a child who has a milder or a more severe form of the disorder.

Complications

Depending on where the noncancerous tumors grow and their size, they can cause severe or life-threatening complications. Here are some examples:

• Too much fluid in and around the brain. One type of noncancerous brain growth, subependymal giant cell astrocytoma, can grow along the lining of the fluid-filled spaces in the brain, called ventricles. The tumor can block the flow of fluid that helps protect the brain, causing fluid to build up around the brain. This buildup is called hydrocephalus. Symptoms can include a head size that is larger than expected, nausea, headaches and behavior changes.
• Heart complications. Growths in the heart, usually in infants, can block blood flow or cause problems with heart rhythm.
• Kidney damage. Growths in the kidney can be large and cause potentially serious — even life-threatening — kidney problems. Growths in the kidney can cause high blood pressure or bleeding or lead to kidney failure. Rarely, kidney growths can become cancerous.
• Lung failure. Growths in the lungs damage the lung tissue and can lead to collapsed lungs. The growths interfere with how well the lungs can provide oxygen to the rest of the body.
• Increased risk of cancerous tumors. Tuberous sclerosis is linked with an increased risk of developing cancerous tumors in the kidneys and brain.
• Vision damage. Growths in the eye can interfere with vision if they block too much of the retina, though this is rare.