By Randy Dotinga
Wednesday, January 28, 2009 12:00 AM
WEDNESDAY, Jan. 28 (HealthDay News) -- Researchers have linked a genetic variation to a common form of epilepsy in children, potentially paving the way toward greater insight into the disorder.
"It's the first step toward developing a diagnostic test, which can help provide a more precise diagnosis and information about which particular drug or treatment may be effective," said study senior author Dr. Deb Pal, a pediatric neurologist and research scientist at Columbia University.
Epilepsy affects an estimated 60 million people worldwide, about 1 percent of the entire population, Pal said. In the United States, an estimated three million people have the disorder.
The condition causes seizures when electrical signals in the brain are disrupted. In the worst cases, the seizures rob people of consciousness and control over their bodies.
In some cases, the cause of epilepsy is obvious, Pal said. It may develop after a head injury or brain tumor, for instance.
But the cause is unclear about two-thirds of the time, he said. However, "in the last 15 years, there's been a concerted effort to try to get to the bottom of the majority of these."
Genetics appear to play a role. "We know that in twins, if one twin has it, there's a higher chance the other twin will have it," Pal said. Also, researchers have discovered that families prone to unusual types of epilepsy share unusual genes, another indication of a genetic link, he said.
In the new study, researchers decided to look at the most common type of epilepsy in children, known as Rolandic epilepsy.
According to the Epilepsy Foundation, Rolandic epilepsy affects 16 percent of children who develop epilepsy before age 15. Patients typically have seizures during sleep, and the condition disappears in 95 percent of those affected by the time they turn 14.
The study authors examined the genomes of 38 families with members who had the condition. They found a gene variation -- in a gene called ELP4 -- that appeared to be linked to Rolandic epilepsy.
The findings were published online Jan. 28 in the European Journal of Human Genetics.
The full meaning of the research remains to be determined, Pal said. "In the future, it could be used as part of a test to predict those who are at risk and those who are not at risk" for developing the condition, he said.
The finding also might provide insights into conditions such as ADHD and speech dyspraxia, a disorder in which a person has delayed speech development because of motor coordination difficulties, according to background information with the study.
For the moment, there's not much doctors could do if they knew a child was at risk of epilepsy, but that could change, Pal said.
Dr. Orrin Devinsky, professor of neurology, neurosurgery and psychiatry at New York University School of Medicine, said the next challenge is to figure out how the genetic variation affects the makeup of the brain.
"More information is great, but we need to convert basic science data into improved clinical care, a big challenge," said Devinsky, who's familiar with the findings of the new study.
Learn more about epilepsy from the Epilepsy Foundation.
SOURCES: Deb Pal, M.D., Ph.D., research scientist, Columbia University, New York City; Orrin Devinsky, M.D., professor of neurology, neurosurgery and psychiatry, New York University School of Medicine, New York City; Jan. 28, 2009, European Journal of Human Genetics, online