Is epilepsy genetic?

Advances in science and medicine over the last decade have led to a better understanding of the ways genetic factors contribute to epilepsy.

Not all epilepsies that are due to genetic causes are inherited.

The genetics of epilepsy is a new and emerging field. For some individuals, it is not yet possible to determine whether their seizures are due to genetic factors.

In general, if a person has a first-degree relative (mother, father, sibling) with epilepsy, the risk of developing epilepsy by the age of 40 is less than 1 in 20 (Peljto et al. 2014). The risk differs somewhat between focal and generalized epilepsy. There is an increased risk of developing epilepsy if the first-degree relative has a generalized epilepsy rather than focal epilepsy (Peljto et al. 2014; Helbig et al. 2016). These estimates come from population-based studies, meaning they are based on the average across a large group and may not apply for all individuals.

The likelihood of inheriting epilepsy may differ significantly if a person has a relative with a known genetic epilepsy diagnosis. In this case, the chance of developing epilepsy depends on the specific gene and inheritance pattern involved.

To fully appreciate this, we first need to review a few basic genetic terms.

Genes are sequences of DNA (deoxyribonucleic acid) that determine different proteins made in the body. These proteins have a variety of functions and ultimately determine how we develop, grow and function. There are about 20,000 genes in the human genome. With a few exceptions, humans have two copies of every gene: one inherited from each parent.

A genetic variant is a change in the DNA sequence, which can cause the gene not to work properly and ultimately can affect how the gene (protein) functions.

A de novo genetic variant arises for the first time in one individual. Usually, this is caused by a random change in the DNA of the egg or the sperm cell of the parent but is not otherwise present in either parent.

For some genetic conditions, not everyone with a disease-causing variant will develop the symptoms of the disease. This phenomenon is called incomplete penetrance.

Certain types of epilepsy are associated with specific genetic changes, including changes in an individual gene or changes in a chromosome.

Research is currently ongoing in many medical centers and laboratories around the world to help understand the role of genetics in the development of epilepsy. One long term goal of this research is precision medicine. This means individuals with genetic epilepsies would be treated with approaches specifically targeted to their genetic diagnosis.

Although there are many types of research studies, three main types relate to the field of epilepsy genetics:

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There are currently a limited number of clinical trials available to individuals and families with some forms of genetic epilepsies, but we anticipate the number of trials will continue to increase. The following links are a good place to start for information about currently available trials for genetic epilepsies:

Helbig I, Heinzen EL, Mefford HC, and Ilae Genetics Commission. Primer Part 1-The building blocks of epilepsy genetics. Epilepsia, 57 (2016): 861-8.

Peljto AL, Barker-Cummings, Vasoli VM, Leibson CL, Hauser WA, Buchhalter JR, and Ottman R. Familial risk of epilepsy: a population-based study. Brain, 137 (2014): 795-805.

National Library of Medicine (US). Adapted from Genetics Home Reference [Internet]: ghr.nlm.nih.gov. Bethesda (MD): The Library; 2013 Sep 16.

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Epilepsy and Genes - Epilepsy Foundation