Tuberous sclerosis is caused by a genetic mutation that occurs in one of two genes:
- the TSC1 gene, or
- the TSC2 gene
Genetic mutations
Genetic mutations occur when the deoxyribonucleic acid (DNA) inside the gene changes. DNA is the long molecule inside a gene that stores genetic information. If the DNA changes, this alters the genetic information, which can cause a genetic disorder to develop.
Mutations are often inherited from a parent, or they can occur when a sperm or egg is made, and a new mutation is created. Mutations can also occur if DNA is damaged – for example, by natural chemicals (including water and oxygen) or by radiation or sunlight.
Someone with a new mutation will not have a family history of a condition, but they may be at risk of passing on the mutation to their children.
See the Health A-Z topic about Genetics for more information.
The TSC1 and TSC2 genes
Both of these genes are responsible for regulating cell growth. The genetic mutation is thought to affect the gene’s ability to properly control cell growth, leading to the development of multiple tumours throughout the body.
In around a quarter of cases of tuberous sclerosis, a child will inherit one of the mutated genes from one of their parents. If you are a parent who has one of the mutated genes, you have a 1 in 2 chance of passing it on every time you conceive a child. The severity of symptoms can often vary between an affected parent and an affected child.
In the other three quarters of cases of tuberous sclerosis, the mutation occurs for no apparent reason. This is known as a spontaneous mutation.
Currently, there is no way of identifying people who may be more likely to experience a spontaneous mutation.
The chance of getting tuberous sclerosis is the same for both sexes. All ethnic groups are equally affected by the condition.
