There are nearly 3.4 million people living with epilepsy in the United States. Epilepsy is a neurological condition that affects the central nervous system (CNS). Epilepsy, a seizure disorder, comprises many different types of seizures with varying causes. In approximately 30 percent to 40 percent of epilepsy cases, the underlying cause is genetic.
A person’s chances of developing or inheriting genetic epilepsy depend on several different factors, including seizure type and the genetic and inheritance patterns of their epilepsy. The answer to whether one will inherit epilepsy is “maybe.”
Genetics play an important role in several types of epilepsy, but not all of them. When a person inherits a gene or has a set of genes that create a high likelihood of epilepsy, they are said to have genetic epilepsy. For example, there are certain metabolic and chromosomal conditions that are inherited that increase the risk of epilepsy.
Not all cases of genetic epilepsy are inherited, however. Sometimes, spontaneous gene mutations cause epilepsy. Certain specific gene mutations have been shown to cause malformations of the brain, leading to epilepsy.
Assessing a person’s genetic risk isn’t easy. For instance, two children may develop the same type of epilepsy, even though they have mutations in different genes. Moreover, two family members may share the same genetic mutation and both develop epilepsy, but their epilepsy syndromes may manifest in different ways.
Inheritance patterns vary among different types of epilepsy. Some types of epilepsy have an entirely genetic cause. In other cases, genes are just one of several factors in a person’s epilepsy diagnosis.
Other factors that may influence a person’s risk of having genetic epilepsy include:
Epilepsy often runs in families. Heredity refers to the genetic or physical traits that are shared among some family members or are inherited from our biological parents. Inheritance patterns vary between different types of epilepsy.
One study found that a person whose parent or sibling has epilepsy has nearly a 5 percent chance of developing epilepsy by the time they’re 40 years old. That’s more than three times higher than the risk of the general population. The findings also suggest that a person who has a family member with generalized epilepsy is at a slightly higher risk of inheriting epilepsy than if their family member has focal epilepsy.
Generalized epilepsy is characterized by a person’s epileptic seizures beginning in both hemispheres of the brain. In focal epilepsy, seizures are localized and begin in one hemisphere of the brain. Generalized-onset epilepsy is more likely than focal epilepsy to be inherited.
Idiopathic epilepsy is the name given when the seizures’ onset or cause is unknown. Some idiopathic types of generalized epilepsy (juvenile myoclonic epilepsy or epilepsy with generalized tonic-clonic seizures) result from inherited abnormal genes.
People with epilepsy may be concerned about passing on their seizure disorder to their children. However, most children born to parents who have epilepsy do not develop seizures.
If the father does not have epilepsy and the mother has epilepsy, the chances are less than five percent. If the father has epilepsy and the mother does not have epilepsy, the risk is slightly lower. If both parents have epilepsy, the risk is only a bit higher.
Because family history of epilepsy can be a factor, there will always be a possibility your child may develop epilepsy.
People with epilepsy or who have a family history of epilepsy may consider genetic testing and genetic counseling. Through genetic testing, doctors can help determine whether a person’s epilepsy has a genetic cause. Doctors can also identify the nature of epilepsy’s genetic cause.
According to the Epilepsy Foundation, “Genetic counseling is the process of helping people understand and adapt to the medical, psychological, and family effects of how genes are related to disease.”
A genetic counselor undergoes special training in both genetics and in counseling. The role of the genetic counselor is to help you and your health care team interpret, understand, and apply genetic testing results toward a specific, personalized health care plan.
There are different types of genetic tests that can be used to detect epilepsies with a genetic cause. No single test exists to diagnose all genetic epilepsies, so you may need to undergo multiple tests. Genetic tests for epilepsy include an epilepsy gene panel, chromosome microarray, and whole-exome sequencing. Most genetic tests are conducted on DNA material extracted from a blood sample or saliva sample.
Genetic information can be beneficial at many points along the disease process, from diagnosis to treatment, with the goal of realizing full seizure control:
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