Tuberous sclerosis (TSC), also called Bourneville's disease, is a rare genetic disorder that causes noncancerous (benign) tumors to grow in many parts of the body, such as the brain, eyes, heart, kidneys, lungs, and skin.
Symptoms of TSC are highly variable, depending on where the tumors develop. The symptoms of TSC range from very mild to debilitating. For instance, some people may have discolored patches of skin, while others may have seizures or intellectual disabilities (formerly called mental retardation). In rare cases, tumors may develop inside vital organs, leading to organ dysfunction. Tumors in organs, such as the brain, may be life-threatening.
Some people may experience symptoms of TSC at birth. However, most do not develop symptoms until early childhood. Some people may not develop noticeable symptoms until adulthood.
Researchers estimate that TSC affects one out of 5,800-30,000 people worldwide.
Although there is currently no cure for TSC, treatments are available to reduce the symptoms. Common treatments include medications (e.g. anti-seizure drugs, antipsychotic drugs, and/or stimulants), educational and occupational therapy, dermabrasion (a surgical procedure to improve the texture and appearance of skin that has been affected by skin lesions), and surgery. With proper treatment, most people who are mildly to moderately affected by TSC are able to live long, healthy lives. However, people with a more serious form of TSC that affects the vital organs are more likely to experience life-threatening complications. About 25% of severely affected infants die before the age of 10 and 75% die before the age of 25.
Tuberous sclerosis (TSC) is caused by mutations (or abnormalities) in the tuberous sclerosis 1 (TSC1) and/or the tuberous sclerosis 2 (TSC2) gene(s). A person only has to have a mutation in one of these genes to develop TSC.
TSC1 provides the body with instructions on how to produce a protein called hamartin and TSC2 provides instructions on how to produce a protein called tuberin. Although the function of hamartin is poorly understood, researchers believe that it works with tuberin to regulate cell growth. Essentially, these proteins help prevent cells from growing uncontrollably. When the genes are mutated, cells divide too quickly, which leads to the development of tumors throughout the body.
In many cases of TSC, the mutated genes are not inherited or passed down among families. Instead, the mutations occur for unknown reasons.
About one-third of TSC cases are inherited. In such instances, the disorder is passed down as an autosomal dominant trait. This means that if one parent has TSC, there is a 50% chance that his/her child will have TSC. If both parents have TSC, there is a 75% chance that the child will inherit the condition.
SIGNS AND SYMPTOMS
General: Benign tumors can grow in many parts of the body, and symptoms vary depending on where the tumors develop. The most common areas for tumors to grow include the brain, eyes, heart, kidneys, lungs, and skin.
Some people may experience symptoms of TSC at birth. Most, however, do not develop symptoms until they are 2-6 years old. Others may not develop noticeable symptoms until adulthood. The age at which symptoms develop does not appear to influence the severity of symptoms. Below are some of the most common symptoms of TSC categorized by their location in the body.
Brain: Tumors may develop on the surface of the brain or inside the brain. Symptoms vary depending on the exact location and size of the tumors. This is because different parts of the brain have different functions. In general, common symptoms include seizures, learning disabilities, intellectual disabilities (formerly called mental retardation), developmental delays, hyperactivity, and aggression. In addition, some people may have autism, a brain disorder that is associated with a wide range of developmental problems, especially in communication and social interaction.
Eyes: Tumors may grow on the part of the eye called the retina, which is located at the back of the eye. The retina sends visual images to the brain where they are perceived. In most cases, tumors in the retina do not cause vision loss or other medical problems. However, these tumors may help doctors diagnose the condition.
Heart: About half of people with TSC develop tumors inside the heart muscle. Infants and young children with TSC often develop heart tumors, called cardiac rhabdomyomas. If these tumors are big or if there are several tumors, blood flow to and from the heart may become blocked, resulting in death. However, in many cases, these tumors do not cause damage, and they often go away without treatment in the first few years of life.
Kidneys: Angiomyolipomas are the most common type of tumors to develop in the kidneys of TSC patients. These tumors are made up of vascular, fatty, and muscle tissues. In many cases, these tumors do not cause any symptoms. However, sometimes the tumors become large enough to cause pain and affect kidney function.
Lungs: Tumors in the lungs may cause shortness of breath, difficulty breathing, a sudden collapsed lung, or coughing. If left untreated, tumors in the lungs may eventually lead to lung failure.
Skin: About 70-80% of people with TSC have some type of skin lesion. The most common ones are small tumors (called angiofibromas) on the face, scalp, or under or around the nails. The affected areas may have patches of light-colored skin or areas of thickened skin. Sometimes facial lesions look like acne. Some patients may develop dermatofibromas, which are benign skin growths that are typically found on the legs. Although most skin tumors caused by TSC do not lead to any medical problems, they may be disfiguring and upsetting to the patient.
General: A person is diagnosed with tuberous sclerosis (TSC) after a clinical evaluation of the patient's signs and symptoms. Imaging studies and a slit lamp test may be performed to look for tumors. If tumors are present, a biopsy may be performed to determine if they are cancerous. Genetic testing is also available.
Imaging studies: Imaging studies, such as computerized tomography (CT) or magnetic resonance imaging (MRI) scans, may be performed to detect the presence of tumors. During these scans, the patient lies still while medical machines take detailed pictures of the internal organs and tumors. These tests are painless and considered non-invasive. However, these tests cannot determine whether or not the tumors are cancerous.
Slit lamp test: During an eye exam, a slit lamp test may be performed to determine if there are tumors on the retina. The slit lamp is a microscope with a light that helps the eye doctor observe the eye under high magnification. The doctor is able to see the front and the back of the eye.
Biopsy: Once tumors are identified, a biopsy may be performed to determine if they are cancerous. A small tissue sample is taken from the patient and analyzed under a microscope to determine if cancerous cells are present.
Genetic testing: Genetic testing may also be performed to confirm a diagnosis of TSC, although it is often not needed. A sample of the patient's blood is analyzed in a laboratory to determine if the patient has one of the two possible genetic mutations associated with TSC. Mutations can be identified in about 80% of cases.
If there is a family history of TSC, prenatal genetic testing, such as amniocentesis or chorionic villus sampling, is available to determine if the fetus has the disorder. However, there are risks associated with prenatal testing, including miscarriage. Therefore, people should discuss the potential risks and benefits of testing before making any medical decisions.
Heart problems: Infants and young children with tuberous sclerosis (TSC) often develop heart tumors, called cardiac rhabdomyomas. In many cases, these tumors do not cause damage and they often go away without treatment in the first few years of life. However, if the tumors in the heart are large or numerous, they may block blood flow to and from the heart and/or lead to abnormal heart rhythms (called arrhythmias). These complications of TSC may be fatal.
Kidney problems: TSC may cause tumors to grow in the kidneys, which may damage or block the kidneys or even lead to kidney failure. These tumors may also cause bleeding. In rare cases, benign tumors in the kidneys may become cancerous. A type of kidney cancer called renal cell carcinoma has been observed in patients with TSC.
Lung failure: Tumors in the lungs can damage the lungs and possibly cause a collapsed lung or respiratory failure. These conditions may be life-threatening.
Neurological problems: Tumors in the brain can block the flow of cerebral spinal fluid (CSF) within the brain. The CSF is important because it supports the brain, acts as a lubricant, maintains pressure in the skull, and serves as a shock absorber. When CSF is blocked, it can cause various signs and symptoms, including nausea, headaches, and behavioral changes.
Brain tumors can also lead to various types of seizures and intellectual disabilities (formerly called mental retardation).
Vision problems: Tumors in the eye can cause vision loss if they block too much of the retina, which is located at the back of the eye.
General: Although there is currently no cure for TSC, treatments are available to reduce symptoms and prevent complications. Common treatments include medications (e.g. anti-seizure drugs), educational and occupational therapy, dermabrasion, and surgery.
Occupational therapy: Patients with intellectual disabilities (formerly called mental retardation) may benefit from occupational therapy. During sessions, a therapist may help the child learn to perform activities of daily living, such as feeding, dressing, and communicating with others. Some patients work with therapists who specialize in disorders associated with intellectual and physical disabilities. Parents and caregivers can ask their children's pediatricians to recommend therapists.
Education: Children with intellectual or learning disabilities caused by TSC must have access to education that is tailored to their specific strengths and weaknesses. According to the Individuals with Disabilities Education Act, all children with disabilities must receive free and appropriate education. The law requires schools to consult with parents or caregivers and tailor educational plans to the patients' needs. The school faculty should document the child's progress in order to ensure that the child's educational needs are being met.
Educational programs vary among patients. In general, most experts believe that children with disabilities should be educated alongside their non-disabled peers. The idea is that non-disabled students will help the patient learn appropriate behavioral, social, and language skills. Therefore, some children affected intellectually by TSC are integrated into mainstream classrooms. Other children with TSC-related intellectual disabilities take special education classes at public schools. Other TSC patients attend special schools designed to teach children with disabilities.
Behavioral therapy: Behavioral therapy may also be beneficial for TSC patients who have cognitive disabilities or autism. Several different types of behavioral therapy are available to help TSC patients improve their communication and social skills, as well as their learning abilities and adaptive behaviors. The specific type of behavioral therapy used depends on the person's individual needs. This is because people experience a wide range of symptoms that require specific treatment.
Applied behavior analysis (ABA) is a type of therapy used to improve the patient's behavior and to teach skills to help the person handle specific situations. The therapist uses positive reinforcement, which means the patient is rewarded when he/she behaves appropriately. ABA is highly structured, and it usually requires 15-40 hours of therapy per week. The therapist usually works one-on-one with the patient and collaborates with the parents/caregivers, teachers, and other significant people in the patient's life to provide treatment that is individualized to meet the patient's needs.
Evidence suggests that behavioral therapy is most effective if it is started in early childhood.
Speech-language therapy: Some patients with TSC may benefit from speech-language therapy if they have intellectual disabilities or if they develop communication skills more slowly than normal children. Qualified speech-language professionals (SLPs) work with the patients one-on-one, in small groups, or in classrooms to help patients improve speech, language, and communication skills. Programs are tailored to patients' individual needs.
Speech pathologists use a variety of exercises to improve the patient's communication skills. Exercises typically start off simple and become more complex as therapy continues. For instance, the therapist may ask the patient to name objects, tell stories, or explain the purpose of an object.
On average, TSC patients receive five or more hours of therapy per week for three months to several years. Doctors typically recommend that treatment is started early to ensure the best possible prognosis for the child.
Anticonvulsants: Anticonvulsant medications may be prescribed to treat seizures. These drugs are typically taken once daily to help prevent seizures from occurring. Phenobarbital (Luminal© Sodium) is one of the oldest and safest anticonvulsants for children. Valproic acid (Depakene© or Depakote©) has also been shown to be a safe and effective treatment for seizures.
Antipsychotic drugs: Antipsychotic drugs have been used to help treat aggressive and repetitive behaviors, as well as hyperactivity in patients with TSC that affects the brain. Commonly prescribed drugs include risperidone (Risperdal©), olanzapine (Zyprexa©), and quetiapine (Seroquel©).
Stimulants: Stimulants, such as methylphenidate (Ritalin©) and amphetamines (Adderall© or Dexedrine©), may help treat hyperactivity and/or attention-deficit/hyperactivity disorder (ADHD), which may occur in some TSC patients. These drugs help increase the patient's ability to concentrate and reduce the individual's overactivity.
Surgery: If tumors damage vital organs (such as the brain, heart, or kidneys), they may need to be surgically removed. In some cases, surgery may help improve organ function. In other cases, it may only prevent further damage. Surgery may also be performed to remove tumors that are disfiguring or bothersome to the patient.
Dermabrasion: Surgical procedures, such as dermabrasion or laser treatment, may help improve the appearance of skin lesions. During dermabrasion treatment, an abrasive tool or chemical is used to remove the top layers of the skin in order to improve its texture and appearance.
Gene therapy: There is a lack of research on the use of gene therapy for TSC. Gene therapy is an experimental procedure that involves replacing, inactivating, or inserting a new gene to fight against specific diseases.
Currently, there is a lack of scientific data on the use of integrative therapies for the treatment or prevention of tuberous sclerosis (TSC).
There is currently no known method of prevention against tuberous sclerosis (TSC). Most cases occur randomly and are not inherited.
Prenatal DNA testing, such as amniocentesis or chorionic villus sampling, may be performed if there is a family history of TSC. However, there are serious risks associated with prenatal testing, including miscarriage. Therefore, patients should discuss the potential health risks and benefits of prenatal genetic testing before making any health-related decisions.
People with family histories of TSC can meet with genetic counselors. These professionals can help patients understand the risks of having a child with TSC. A genetic counselor can also explain the different types of genetic tests, including their potential risks and benefits. These counselors can also help patients understand the results and implications of genetic tests.
This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).
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