Physicians at a Boston hospital adjusted medical management for nearly three-quarters of patients with infantile- or childhood-onset epilepsy who were diagnosed with genetic epilepsy, researchers reported at the annual meeting of the American Epilepsy Society. The findings provide new insight into the usefulness of genetic tests in children with epilepsy of unknown cause.
“. Genetic testing should be included as part of the standard evaluation of individuals with unexplained pediatric epilepsy as a means of achieving diagnostic precision and informing clinical management,” study lead author Isabel Haviland, MD, a neurologist with Boston Children’s Hospital/Harvard Medical School, said in an interview.
According to Dr. Haviland, the causes of epilepsy are unexplained in an estimated two-thirds of pediatric epilepsy cases. “Increasingly, when genetic testing is available, previously unexplained cases of pediatric epilepsy are being found to have single-gene etiologies,” she said. “Though a genetic diagnosis in this population has implications for medical care, the direct impact on medical management in a clinical setting has not been measured. We aimed to describe the impact of genetic diagnosis on medical management in a cohort of individuals with pediatric epilepsy.”
Researchers tracked 602 patients at Boston Children’s Hospital who received next-generation gene sequencing testing from 2012 to 2019. Of those, Dr. Haviland said, 152 (25%) had a positive result that indicated genetic epilepsy (46% female, median age of onset = 6 months [2-15 months]). These patients were included in the study.
“We documented an impact on medical management in nearly three-fourths of participants (72%),” Dr. Haviland said. “A genetic diagnosis affected at least one of four categories of medical management, including care coordination (48%), treatment (45%), counseling about a change in prognosis (28%), and change in diagnosis for a few individuals who had a prior established diagnosis (1%).”
As examples, she mentioned three cases:
- Testing revealed that a subject has a disease-causing genetic variant in a gene called PRRT2. “This gene is involved in the release of neurotransmitters in the brain,” Dr. Haviland said. “Thanks to his diagnosis, he was treated with the antiseizure medication oxcarbazepine, which is often effective for epilepsy caused by variants in this gene. He had excellent response to the medication and later became seizure free.”
- A subject had a variation in the SCN1A gene that causes types of epilepsy. “At the time of his diagnosis, there was a trial for a medication called fenfluramine being offered for individuals with SCN1A variants, and his family elected to participate,” she said. “This medication was later approved by the [Food and Drug Administration] for SCN1A-related epilepsy.”
- Testing identified disease-causing variant in the GRIN2A gene in another subject. “This gene is involved in brain cell communication,” Dr. Haviland said. “This individual was treated with memantine, which acts on the specific biological pathway affected by the gene. This treatment would not have been considered without the genetic diagnosis as it is currently only approved for Alzheimer’s disease.”
In addition, Dr. Haviland said, researchers found that “there was impact on medical management both in those with earlier age of epilepsy onset (under 2 years) and those with later age of onset, as well as both in those with developmental disorders (such as autism spectrum disorder, intellectual disability and developmental delay) and those with normal development.
As for the cost of genetic tests, Dr. Haviland pointed to a 2019 study that she said estimated epilepsy panel testing runs from $1,500 to $7,500, and the whole exome sequencing from $4,500 to $7,000. “Insurers sometimes cover testing, but not always,” she said. “In some cases, insurance will only cover testing if it is documented that results will directly alter medical management, which highlights the importance of our findings.”
No study funding was reported. Dr. Haviland and several other authors report no disclosures. One author reports consulting fees from Takeda, Zogenix, Marinus, and FOXG1 Research Foundation. Another author reports research support from the International Foundation for CDKL5 Research.