Epilepsy is not purely a genetic disorder, but genetics play a significant role in a large share of cases. More than 40% of adults with epilepsy have at least one genetic variant linked to their condition, according to research presented at the American Epilepsy Society Annual Meeting. The rest of cases result from brain injuries, infections, stroke, tumors, or causes that remain unknown. So epilepsy sits in a gray zone: it can be genetic, it can be acquired, and in many people it involves some combination of both.
How Genetics Contribute to Epilepsy
Epilepsy is really an umbrella term for a group of conditions that all share a tendency toward seizures. Some forms are caused by a single gene mutation. Others involve multiple genes, each contributing a small amount of risk. And many cases have no identifiable genetic cause at all.
The International League Against Epilepsy, the main global authority on the condition, recognizes genetic causes as a distinct category. This includes both specific gene mutations and chromosomal abnormalities. Importantly, the classification no longer requires a family history. That’s because many genetic epilepsies are caused by “de novo” mutations, meaning the genetic change happened for the first time in the affected person rather than being passed down from a parent. In severe forms of epilepsy that begin in infancy, de novo mutations account for 30 to 50% of cases.
This distinction matters. A person can have a genetic form of epilepsy without anyone else in the family ever having seizures.
Genes Most Often Involved
Hundreds of genes have been linked to epilepsy, but they tend to cluster around a few key functions in the brain. Many affect ion channels, the tiny gates on brain cells that control electrical signaling. When these channels don’t open or close properly, neurons can fire too easily or too often, triggering seizures.
One well-studied example is the KCNQ2 gene, which encodes a potassium channel. Mutations in this gene can cause seizures within the first week of life. The severity varies widely. Some newborns experience a mild, self-limiting form where seizures resolve on their own. Others develop a severe condition with multiple daily seizures involving body stiffening, jerking movements, and changes in breathing or heart rate. Children with the more severe form may go on to be diagnosed with recognized epilepsy syndromes like West syndrome or Lennox-Gastaut syndrome.
Other commonly implicated genes affect sodium channels (involved in Dravet syndrome, a severe childhood epilepsy) or signaling pathways that regulate how brain cells grow and connect. A signaling cascade called mTOR, for example, is disrupted in several genetic epilepsies and has become a target for more specific treatments.
Risk of Passing Epilepsy to Children
If you have epilepsy and are wondering about the risk to your children, the numbers are reassuring for most people. The general population risk of developing epilepsy by age 40 is about 1.4%. For children of a parent with epilepsy, that risk rises to roughly 3.9%, meaning more than 96% of those children will not develop the condition.
The risk varies depending on the type of epilepsy. Generalized epilepsies, which affect both sides of the brain from the start, carry the highest familial risk. Children and siblings of someone with this type face about an 8.2% chance of developing epilepsy. For focal epilepsies with no known structural cause, the risk to children is around 3.5%, while siblings face no meaningful increase over the general population. When focal epilepsy has a clear structural or metabolic cause (like a brain injury or tumor), the risk to family members is essentially the same as the general population.
There’s also a sex-based pattern. Children of mothers with epilepsy face a higher risk (5.3%) than children of fathers with the condition (1.9%). The reasons for this difference aren’t fully understood.
What Genetic Testing Can Reveal
Genetic testing for epilepsy has become increasingly accessible and can provide a definitive answer for some people. In pediatric patients, targeted gene panels identify a genetic cause in about 40% of cases. Broader testing that examines all protein-coding genes has a slightly lower yield, finding a diagnosis in roughly 28 to 30% of cases, partly because the larger scope introduces more ambiguous results.
In the American Epilepsy Society study of 286 adults, 41% had a genetic variant related to their epilepsy. Another 53% had variants of uncertain significance, meaning genetic changes were found but their role in causing seizures isn’t yet clear. As scientific databases grow, some of those uncertain results will eventually be reclassified as meaningful.
A genetic diagnosis can do more than satisfy curiosity. In some cases, it directly changes treatment. Dravet syndrome, caused by mutations in a sodium channel gene, is a prime example. Certain common seizure medications actually make seizures worse in people with this mutation. Knowing the genetic cause steers doctors away from those drugs and toward therapies that work with the specific biology of the condition. Similar precision approaches exist for a handful of other genetic epilepsies, including some caused by problems with how the brain uses glucose or vitamin B6.
When Epilepsy Is Not Genetic
Roughly half of all epilepsy cases have a clearly non-genetic origin. Head injuries, strokes, brain infections like meningitis or encephalitis, brain tumors, and abnormal brain development during pregnancy can all cause epilepsy. In older adults, stroke is one of the most common triggers. In children, infections and developmental brain abnormalities are frequent causes.
Even in these acquired cases, genetics may play a background role. Two people can sustain similar brain injuries, but only one develops epilepsy afterward. This suggests that genetic factors may influence how easily the brain develops a seizure tendency after damage. The line between “genetic” and “acquired” epilepsy is blurrier than it might seem, and for a significant number of people, the cause is never definitively identified.