What is Tuberous Sclerosis Complex (TSC): Causes, Symptoms, Treatment, Complications, Diagnosis

What is Tuberous Sclerosis Complex?

Tuberous Sclerosis Complex (TSC) or Tuberous Sclerosis is a rare genetic disorder that causes development of tumours in multiple vital organs such as brain, heart, kidneys, lungs and skin.(1) There is abnormal multiplication of cells which causes growth of tumours. These tumours are usually benign in nature, i.e. they are not cancerous but they can cause issues in the area that they are growing in. They affect the central nervous system of the body and associated with multiple symptoms such as behavioural issues, developmental delays, seizures, kidney diseases and skin issues.(1,2)

The term Tuberous Sclerosis is derived from the word ‘tuber’ referring to nodular growth pattern and ‘sclerosis’ which refers to calcification of these tumours with age. Tuberous Sclerosis Complex was first discovered more than 100 years ago by a French neurologist named Désiré-Magloire Bourneville and thus, it was called as Bourneville’s disease or epiloia.

Causes of Tuberous Sclerosis Complex

Tuberous Sclerosis complex is a genetic disorder and it is caused by genetic mutation of the genes TSC1 or TSC2. These genes regulate the growth of cells and mutation of these genes can cause uncontrolled growth and multiplication of the tumours. In majority of the cases, there is no family history and it is not inherited from family members. In few cases, there is evidence of inheritance. The symptoms are usually noted during childhood and often soon after birth.

Signs and Symptoms of Tuberous Sclerosis Complex

As mentioned earlier, tuberous sclerosis complex can affect any part of the body like brain, lungs, kidneys, heart, eyes, skin, etc. The severity of the symptoms of Tuberous Sclerosis Complex can range from mild to severe depending on the location and size of the growth and it also varies from one person to another. The most common symptoms are listed below:(3,4)

Skin Issues: Development of small patches over the skin that are light coloured and may be thickened. There may be red bumps under and around the nails. Some people (mostly children) may develop facial growths resembling acne.

Seizures: This is usually the first noted symptom of tuberous sclerosis complex. It is associated with growths in the brain causing seizures. In children, this is revealed as repetitive spasms of the heads and lower limbs (referred to as infantile seizures).

Renal Disorders as a Symptom of Tuberous Sclerosis Complex: People affected by tuberous sclerosis complex can have renal disorder from abnormal growth over the kidneys. These growths continue to grow in size and number with age and lead to further complications.

Cognitive Disabilities: Tuberous sclerosis complex can lead to developmental delays and issues with learning abilities and intellectual learning. It is also known to cause mental health issues such as ADHD (attention deficit hyperactivity disorder) and autism.

Lung Problems as a Symptom of Tuberous Sclerosis Complex: Growths and tumours in lungs can cause shortness of breath and coughing. These are more common among females than males.

Cardiac Conditions as a Sign of Tuberous Sclerosis Complex: There may be heart related issues from growths over the heart. These however shrink with age.

Retinal Issues as a Symptom of Tuberous Sclerosis Complex: There may be white patches over the retina. These however do not interfere with vision.

Complications of Tuberous Sclerosis Complex

Based on the size and location of the tumour, there can be serious complications associated with tuberous sclerosis complex including death. Some of the common complications are discussed below:(5,6)

Cardiac Issues: Growths in heart can cause blockage and can causes issues such as dysrhythmia.

Neurological Issues: Some growths in brain can interfere with flow of cerebrospinal fluid within the brain. This leads to a condition called as hydrocephalus, where there is build-up of fluid within the brain. This is associated with abnormally large head size, nausea, headaches, behavioural issues etc.

Lung Problems as a Complication of Tuberous Sclerosis Complex: There may be lung collapse or fluid collection around the lungs from growths in lung which interfere with normal lung functions.

Visual Problems: Growth over the retina can cause visual impairment. However, this is very rare.

Malignancy: Benign growths over kidneys and brains can turn malignant or cancerous.

Diagnosis of Tuberous Sclerosis Complex

Seizures and delayed development are the first signs to look out for in diagnosis of tuberous sclerosis complex:(1,5,7) A detailed case history is obtained followed by a clinical examination. A series of confirmatory tests are done as listed below:

In the recent times, tests are available to check the TSC1 and TSC2 genes for pathogenic mutations causing TSC1 or TSC2 protein inactivation.(8,9)

Treatment and Management of Tuberous Sclerosis Complex

There is no universal treatment for tuberous sclerosis complex. Treatment is based on the symptoms noted and customized for each patient as per his or her requirements. Regular examination and monitoring are done throughout life. Some specific treatment includes:(1,7)

Cognitive and Behavioural Issues:

Patients suffering from cognitive problems due to tuberous sclerosis complex are advised following treatment:

Managing Skin Problems Due to Tuberous Sclerosis Complex:

Skin growths can be managed by laser therapies to improve the appearance of the skin.

Tumours Related to Tuberous Sclerosis Complex:

Depending on the size and location of the tumours, surgical intervention may be warranted. Various options of surgery are available such as laser therapy, radiation therapy or conventional surgery.(5,6)

Medication support is often needed for most of the symptoms.

Conclusion

Tuberous Sclerosis Complex (TSC) is an autosomal genetic disorder which is caused by mutation of specific genes. It is often noted in childhood which begins as developmental delay and seizures. The condition is associated with abnormal growth over multiple locations such as brain, lungs, skin, eyes, kidneys, heart etc. The symptoms arise from the complications caused by the location and size of the tumours. These tumours are mostly benign but can cause serious complications including death. Surgical interventions may be recommended for removing the causative tumours, but this depends on the size and location of the tumours. While some affected person can lead a normal life with few complications, some individuals can suffer from life threatening complications.

References:

  1. https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Tuberous-Sclerosis-Fact-Sheet
  2. https://ghr.nlm.nih.gov/condition/tuberous-sclerosis-complex
  3. https://www.tsc.org.nz/what-is-tsc
  4. https://www.tsalliance.org/about-tsc/what-is-tsc/
  5. https://www.ncbi.nlm.nih.gov/books/NBK1220/
  6. https://www.ncbi.nlm.nih.gov/books/NBK538492/
  7. https://www.nhs.uk/conditions/tuberous-sclerosis/
  8. Hoogeveen-Westerveld M, Ekong R, Povey S, Mayer K, Lannoy N, Elmslie F, Bebin M, Dies K, Thompson C, Sparagana SP, Davies P, van Eeghen AM, Thiele EA, van den Ouweland A, Halley D, Nellist M. (2013, Jan) Functional assessment of TSC2 variants identified in individuals with tuberous sclerosis complex. Human Mutation. 34(1): 167-75.
  9. Caban C, Khan N, Hasbani DM, Crino PB. (2016, Dec) Genetics of tuberous sclerosis complex: implications for clinical practice. The Application of Clinical Genetics. 10: 1-8.

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