Tuberous sclerosis (TS) is a rare genetic condition. Sometimes called tuberous sclerosis complex (TSC), the disorder causes noncancerous (benign) tumors to grow in the brain and other vital organs, and on the skin.
Tubers are root-shaped growths, and sclerosis means hardening of tissue.
TS can be due to either heredity or spontaneous gene mutation. Some people have only mild symptoms while others experience developmental delay, autism, mental retardation, seizures, tumors, and skin abnormalities. The disorder can be present at birth, but symptoms may be mild at first, taking years to develop fully.
There is no cure for TS, but most patients can expect a normal lifespan. Treatments are targeted to individual symptoms, and careful monitoring by a physician experienced with TS is advised.
Approximately one million people have been diagnosed with TS around the world. According to the Tuberous Sclerosis Alliance, there are about 50,000 cases in the United States (TSA, 2012). The condition is very difficult to recognize and diagnose, so the actual number of cases could be higher.
The TSA also reports that approximately one-third of cases are inherited, and two-thirds are thought to be from spontaneous genetic mutation. If one parent has TS, the child has a 50 percent chance of inheriting it (TSA, 2012).
Scientists have identified two genes (TSC1 and TSC2) that can cause TS, but having only one of them can result in the disease. Researchers are working to find out exactly what each of these genes does and how they affect TS. It is thought that they suppress tumor growth and are important in fetal development of the skin and brain.
A parent with a mild case of TS may not even be aware of the condition until a child is diagnosed. If only one parent passes on the gene mutation, the child can get TS. Two thirds of cases of TS are the result of spontaneous mutation, with neither parent passing on the gene. The reason for this mutation is currently a mystery, and there is no known way to prevent it.
Diagnosis of TS can be confirmed with genetic tests. When considering genetic testing for family planning purposes, it is important to remember that only a third of TS cases are due to heredity. If there is a family history of TS, it is possible to get genetic testing to see if you carry the gene.
There is a broad range of symptoms of TS, and they vary greatly from one person to another. Very mild cases can present with few, if any, symptoms. In other cases, the patient suffers from a variety of intellectual and physical disabilities.
Symptoms of TS can include:
- developmental delays
- mental retardation
- abnormal heart rhythm
- noncancerous tumors or calcium deposits on the brain
- noncancerous tumors on the kidneys or heart
- growths around or underneath fingernails and toenails
- growths on the retina or pale patches on the eye
- growths on gums or tongue
- pitted teeth
- areas of the skin that have decreased pigment
- red patches of skin on the face
- raised skin with a texture like an orange peel, usually on the back
TS is diagnosed by genetic testing or through a series of tests that includes:
- magnetic resonance imaging (MRI) of the brain
- computed tomography (CT) scan of the head
- electrocardiogram (EKG)
- kidney ultrasound
- eye examination
- looking at the skin under a Wood’s lamp (ultraviolet light)
Seizures or delayed development are often the first sign of TS. There is a wide range of symptoms associated with this condition, and a precise diagnosis will require a CT scan and MRI alongside a full clinical exam.
The tumors from TS are not cancerous, but if untreated, may become very dangerous.
Tumors in the Brain
The flow of cerebral spinal fluid can become blocked by brain tumors.
Tumors in the Heart
Heart tumors can cause problems at birth by blocking blood flow or causing irregular heartbeat. These tumors are usually large at birth, but generally get smaller as the child ages.
Tumors in the Kidney
Large tumors can get in the way of normal kidney function and lead to kidney failure.
Tumors in the Eye
If tumors in the eye grow too large, they can block the retina, causing vision loss or blindness.
When children show signs of developmental delay, behavioral problems, or mental impairment, early intervention can significantly improve their ability to function.
Serious complications from TS include uncontrollable seizures and tumors in the brain, kidney, and heart. If not treated, these complications can lead to premature death.
People diagnosed with TS should find a doctor who understands how to monitor and treat the condition. Because the symptoms vary so greatly in individual cases, so does the long-term outlook.
There is no known cure for TS, but with good medical care, a normal lifespan can be expected in most cases.
There is no single universal treatment for TS. Instead, treatment is geared toward individual symptoms. Because these symptoms can vary so much, so do the treatments. A treatment plan must be tailored to meet the needs of each patient as symptoms develop. That’s why a physician who understands TS should conduct regular exams and monitor patients throughout their lives. Monitoring should include regular kidney ultrasounds to check for tumors.
Treatments for specific symptoms are described below.
Seizures are very common among people with TS and can impact quality of life. Medications can sometimes get seizures under control. In cases where patients continue to have too many seizures, brain surgery can be performed.
Mental Disability and Developmental Delay
Special educational programs, behavioral therapy, occupational therapy, and medications are all used to help those who have mental and developmental problems.
Growths on Skin
Lasers can remove smaller growths on the skin and improve appearance.
Surgery can remove tumors and improve the function of vital organs. In April 2012, the U.S. Food and Drug Administration granted accelerated approval for the use of a drug called everolimus to be used in adults with TS who have benign tumors of the kidney (FDA, 2012).
As medical care continues to advance, treatment for the symptoms of TS is also improving. Research is ongoing, but there is currently no cure.