University of Utah medical researchers have identified a gene with mutations that cause febrile seizures and contribute to a severe form of epilepsy known as Dravet syndrome in some of the most vulnerable patients – infants 6 months and younger.
The discovery, published online in PLoS Genetics, means some infants with Dravet syndrome, a type of epilepsy that often begins with fever-induced (febrile) seizures, would benefit from genetic testing to identify whether they have a mutation in the SCN9A gene, which the researchers found causes seizures by affecting sodium channels in the brain. Infants who have the mutation might well be better off not receiving sodium channel blockers, some of the most common anticonvulsant drugs, because they could make a sodium channel-induced seizure worse, the researchers report.
The study was a collaboration of researchers from several departments in the U of U School of Medicine and College of Pharmacy, as well as national and international colleagues. First author Nanda A. Singh, Ph.D., a researcher in the University's Eccles Institute of Human Genetics, said the SCN9A mutation is the fifth gene discovered to cause febrile seizures and, before now, was not suspected in seizures or epilepsy.
"This new gene gives us a much needed novel target for developing more effective drugs to treat those children with debilitating seizures," Singh said.
Groundwork for the study was laid by two U of U School of Medicine physicians, Joel Thompson, M.D., and Francis M. Filloux, M.D., professor of pediatrics and neurology, who in the 1990s met a patient whose family had a history of the febrile seizures. After studying the DNA of 46 members of the extended family, researchers at the U of U identified an area on chromosome 2 as a likely place to find the gene mutation associated with the family's seizures. Using that data, they pinpointed the SCN9A mutation as the seizure-causing gene in the family.
To confirm SCN9A's role, the researchers used technology pioneered by the University of Utah's 2007 Nobel laureate in medicine, Mario R. Capecchi, Ph.D., to create mouse models with the gene mutation. The researchers tested the animals for seizures and found the mice with the SCN9A mutation had significantly lower thresholds for developing seizures than mice without the mutation.
"The mouse data confirmed that the SCN9A mutation is causing the febrile seizure disease in this family," Singh said. The researchers further showed the SCN9A seizure-causing role in approximately 5 percent of 92 unrelated febrile syndrome patients.
The SCN9A gene provides instructions for the body to make sodium channels, which act as conduits and gates to let sodium ions into cells and help conduct electricity for neurons to communicate. But when the gene mutates, it can cause seizures by altering sodium channel function in the brain and preventing neurons from firing properly. Mutations in four other genes had been shown in other studies to cause febrile seizures, and one sodium channel gene in particular, SCN1A, has been found in about half of patients with Dravet syndrome. In DNA collected by Belgium researchers, headed by Peter De Jonghe, Singh and her colleagues found additional SCN9A mutations in about 9 percent of Dravet syndrome patients, while 6 percent had both SCN9A and SCN1A gene mutations.
For infants and children who suffer febrile seizures or have Dravet syndrome, the study offers hope where there often is little to be found, according to Kris Hansen, president of the Epilepsy Association of Utah and mother to a child with Dravet syndrome. "Dravet is such a hard syndrome to control, and any research that gives us reasons for what is happening with our children and hope for the future is absolutely amazing," Hansen said. "This medical breakthrough will bring prospects of relief to families dealing with the ongoing challenges of Dravet syndrome and febrile seizures."
Febrile seizures are the most common form of early childhood seizures and strike up to 1 in 20 children in North America. Most infants outgrow them, but in some cases the seizures continue into adulthood. Epilepsy is a disorder of many types of seizures that affects nearly 3 million people in the United States, with approximately 200,000 new cases reported each year. Patients with Dravet syndrome can have febrile and other seizures severe enough to stunt mental and social development.
Because half of Dravet syndrome patients have SCN1A mutations, these patients are tested for that form of the disorder for the mutation. In those who don't have the SCN1A mutation, Singh suggests a second test could determine if they have the SCN9A mutation. In patients who have one or both of the genes, treatment could be modified to exclude sodium channel-blocking drugs.
The study was funded by the National Institutes of Health, Keck Foundation, and the Salt Lake City-based Ben B. and Iris M. Margolis Foundation.
This study was a collaboration of researchers from the University of Utah School of Medicine's Department of Human Genetics, divisions of Pediatric Neurology and Medical Genetics, and the College of Pharmacy's Anticonvulsant Drug Development Program. Researchers from the University of Washington and University of Antwerp, Belgium, also collaborated on the study. Mark F. Leppert, Ph.D., professor of human genetics in the University of Utah School of Medicine was the study's senior author.
Phil Sahm | EurekAlert!
First time-lapse footage of cell activity during limb regeneration
25.10.2016 | eLife
Phenotype at the push of a button
25.10.2016 | Institut für Pflanzenbiochemie
Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.
This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...
Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion
Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
26.10.2016 | Physics and Astronomy
26.10.2016 | Earth Sciences
25.10.2016 | Earth Sciences