Genetic testing may help identify the cause of someone’s epilepsy. An accurate diagnosis may lead to treatments that control seizures better. But genetic testing is a complicated option that should be thoroughly discussed with your doctor beforehand.
Who should get genetic testing for epilepsy?
Genetic testing tends to be expensive and time-consuming, and it is often not covered by insurance. Therefore, doctors do not ask families to undergo these tests unless there is a clear need. It is most often done in people with:1,2
- Drug-resistant (refractory) seizures
- Other neurological or medical issues that may point to a genetic syndrome
- A strong family history of epilepsy
Most genetic testing for epilepsy is done in children and teens. Adults usually only receive genetic testing if they have unusual, hard-to-diagnose seizures. Results can guide treatment decisions.1,2
Genetic testing is not likely to help if someone’s epilepsy has a known cause, such as brain injury. Genetic testing must be guided by medical experts. This is because results can impact you and your family members in many ways.2
Genetic counseling
Genetic testing is a personal decision. It may not be right for everyone. Genetic counselors are trained to help guide and support people who are considering genetic testing. Genetic counselors who work in an epilepsy center specialize in tests for epilepsy. They will meet with you and your family before and after genetic tests.
Genetic counselors also help people understand the pros and cons of genetic testing. If someone chooses to have genetic testing, a counselor will help explain their test results and provide options for next steps.1,3
Common genetic tests for epilepsy
There is no 1 test used to diagnose genetic epilepsies. This means multiple tests may be needed. The tests used may focus on single genes, groups of genes, or chromosomes. The most common genetic tests for epilepsy are:2
- Epilepsy gene panel – Checks for the most common genes tied to epilepsy
- Chromosome microarray – Looks for extra or missing pieces of chromosomes that could cause epilepsy
- Whole-exome sequencing – Similar to an epilepsy gene panel but looks at a much larger number of genes
- Targeted testing – Used when another family member has a known genetic cause for epilepsy
Most genetic tests require a blood sample. However, in some cases you may need to give a saliva or cheek swab. A skin biopsy is used the least often.2
What can genetic testing tell us?
Certain genetic changes are linked to specific types of seizures. Doctors have also learned that certain genetic variants respond better to certain medicines. This includes:1
- SCN1A variant – Avoid prescribing phenytoin and lamotrigine
- SCN2A and SCN8A variants – High doses of phenytoin are helpful
- SLC2A1 variant – Ketogenic diet is helpful
- PRRT2 variant – Carbamazepine is helpful
- PLCB1 variant – Inositol is helpful
- ALDH7A1 variant – Pyridoxine is helpful
- PNPO variant – Pyridoxal-5-phosphate is helpful
- KCNQ2 variant – Ezogabine is helpful for some types of seizures
- KCNT1 variant – Quinidine is helpful for some types of seizures
- GRIN2A variant – Memantine and dextromethorphan are helpful for some types of seizures
- TSC variant – Everolimus is sometimes helpful
Testing positive for a genetic variant may or may not help doctors better understand or treat epilepsy. Testing positive does not automatically mean the person has epilepsy or will develop it. It may simply suggest a risk of developing epilepsy. Or, it may help family members understand their chances of having a child with epilepsy. More research is needed to better understand how genetic changes impact someone's epilepsy.1