Family history of epilepsy: does epilepsy run in families?

Epilepsy is a condition that affects the brain and causes seizures. The NHS describes it as happening when the normal electrical activity in the brain changes. When a close relative has it, it is natural to ask whether the same will happen to you or to your children.

A family history of epilepsy is described as a risk factor, which means it is linked with a somewhat higher chance of developing the condition compared with people who have no affected relatives. It is not a prediction. Many people with a relative who has epilepsy never have a seizure, and many people with epilepsy have no affected relatives at all.

The sources used for this page do not give a single figure for the chance of epilepsy passing from parent to child, because the answer depends heavily on the type of epilepsy and on the particular genes involved. A neurologist or clinical geneticist is the right person to give a personalised estimate.

The Epilepsy Society explains that a person might start having seizures because of a genetic tendency passed down from one or both parents, a genetic tendency that is a new change in the person's own genes, or a structural change in the brain. These routes are not mutually exclusive.

It also describes a concept called a seizure threshold. This is part of our genetic make-up, it says, and it can be passed from parent to child. Some researchers, according to the same source, now believe the chance of developing epilepsy is probably always genetic to some extent, so that even seizures that begin after a head injury may reflect both the injury and a person's underlying tendency.

In practical terms, that is why one family can have several members with seizures while another family has only one. The tendency can be inherited, but whether and when seizures appear depends on other factors as well.

The NHS notes that epilepsy is sometimes caused by damage to the brain, for example after a head injury, a stroke or an infection. NHS inform groups causes into structural, genetic and infectious categories. Under structural causes it lists problems with the blood vessels supplying the brain such as stroke, brain tumours and severe head injuries, and under infectious causes it lists infections such as meningitis.

This matters for family history because a relative's epilepsy may have had a cause that is not inherited at all. If an uncle developed epilepsy after a serious head injury, for instance, that does not necessarily raise the chance for his nieces and nephews. Finding out what caused a relative's epilepsy, where that is known, is often more useful than simply knowing that they had it.

• Structural: stroke, brain tumour, severe head injury or other change in the brain.

• Genetic: an inherited tendency or a new gene change.

• Infectious: for example meningitis.

• Unknown: for many people no cause is found.

The NHS says the main symptom of epilepsy is usually seizures, and that these can vary widely. Symptoms can include the body becoming stiff or floppy, suddenly falling to the floor, jerking or twitching movements, losing awareness of what is happening around you, or unusual feelings or sensations such as strange smells, numbness or tingling. A seizure usually lasts a few seconds or minutes and stops by itself.

The NHS adds that symptoms of epilepsy often start in young children and in people over 50, but that it can happen at any age. Seizures in childhood linked to a high temperature are called febrile seizures and are different from epileptic seizures.

If you or your child have had a seizure, the NHS says you will need to see a specialist doctor, who will check what caused it and whether you might have epilepsy. They will ask about what happened before, during and after the seizure, and it can help to bring someone who witnessed it.

Tests you might have include an electroencephalogram (EEG) to check electrical activity in the brain, an electrocardiogram (ECG) to check the heart, scans such as MRI or CT, blood tests and genetic testing. The NHS says you will usually be diagnosed with epilepsy if you have had more than one seizure, or if tests show you are at risk of having more.

Genetic testing is one of the tests the NHS lists. Whether it is appropriate in your situation is a decision for the specialist, who will know the type of epilepsy and the pattern in your family.

The NHS says the main treatment is anti-seizure medicine, and that most people have medicines that work well. Rarely, other treatments such as brain surgery, vagus nerve stimulation or a ketogenic diet may be used. People with epilepsy are supported by their GP and a team of specialists with check-ups at least once a year.

Important safety points from the NHS include never missing doses or stopping medicine without advice, keeping a diary of possible triggers such as tiredness, stress, flashing lights or alcohol, and being careful around baths, cooking and swimming. If you have had any type of seizure you must not drive and must tell the DVLA.

Some epilepsy medicines can harm a baby in pregnancy, and some can affect sperm. The NHS says anyone taking epilepsy medicine who could become pregnant, or whose partner could, should discuss treatment with a specialist before pregnancy rather than stop the medicine on their own.

The NHS says to call 999 if you think someone is having a seizure and it is the first time it has happened, it lasts longer than is usual for them or longer than 5 minutes if you do not know, they do not recover as usual or have another seizure without recovering, or they have had 3 or more seizures in 24 hours.

People with epilepsy do not always need to go to hospital after a seizure, because they usually have a care plan. If you have had a seizure for the first time and did not go to hospital, or have a seizure after a long seizure-free period, ask for an urgent GP appointment or contact NHS 111.