Research Highlight December 01, 2014

What is Epilepsy?

Wayne Frankel, Ph.D.
Wayne Frankel, Ph.D.

The term epilepsy refers to a spectrum of brain disorders resulting from a disturbance of the normal pattern of neuron activity. Epilepsy disorders, also known as seizure disorders, range from severe, disabling and life-threatening, to relatively benign conditions. While a single seizure can occur as the result of a head injury or high fever, after a person has had two or more seizures epilepsy is considered.

As a group of disorders, it is one of the most common diseases of the nervous system, but its diverse manifestations and causes demonstrate the complex nature of accurately diagnosing and treating any one form of epilepsy. Imbalances in nerve-signaling chemicals, abnormalities in brain wiring and changes in brain channels are among the many causes of persistent forms of epilepsy. While many types of epilepsy begin in childhood, late-onset epilepsy is being seen increasingly in older people as a result of brain changes due to strokes, tumors or Alzheimers. In addition, epilepsy is a long-term consequence for those suffering traumatic brain injuries.

Current treatments include drug therapy, diet therapy and nerve stimulation, but because the causes of epileptic disorders are so diverse the effectiveness of the available therapies varies significantly from patient to patient.

The Jackson Laboratory has a rich history in epilepsy research. Many of the ion channel genes involved in mouse models of petit mal epilepsy were discovered in the laboratory of Dr. Wayne Frankel at The Jackson Laboratory. The mutations arose spontaneously in the large breeding colonies of mice at the lab; Frankel then went on to discover the causative genes. Dr. Frankel’s laboratory continues to lead the field in epilepsy research using mouse models. His most recent discoveries surround the genetics of epilepsy in closely related sub-strains of mice and unique mutations in sodium channel gene Scn8a.

The Jackson Laboratory has a large variety of mouse models that aid researchers in understanding epilepsy. There are almost 400 genes that are associated with a variety of seizure phenotypes in mice. In some mouse strains, the epilepsy presents as a complex trait, where multiple genes are contributing to the disease. In other cases, the epileptic seizures are the result of single-gene perturbations. Identifying mouse models that recapitulate human epilepsies helps us in our understanding of anticonvulsant drugs. These models also help us to identify the genes that cause epilepsy in human patients as well as those genes that have an effect on our susceptibility to seizures.