Ancient Gene Linked to Epileptic Seizures

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Ancient Gene Linked to Epileptic Seizures

(Ivanhoe Newswire) -- Intense fear, jerking, thrashing, loss of consciousness:

the symptoms of epilepsy plague its victims, but a recently discovered ancient

gene may hold the key to solving the mystery of the condition.

An epileptic seizure is classified as one that has no rhyme or reason, no

previous medical condition to cause it, and no answer as to why it happens. A

seizure occurs when there is a temporary change in electric activity in the

brain, particularly in the cortex. The condition is more prevalent in children

and then again when the victims are in their 50s or 60s.

Recently scientists at Penn State University discovered an ancient gene linked

to epileptic seizures that could open the door to further epileptic research and

treatment.

The gene, Kv12.2, is now known to affect the excitability of nerves within the

brain. In a healthy person, nerves don't fire immensely in reaction to small

stimuli. Between the nerves being in rest and being excited, they maintain

threshold, and for the nerve to fire, something must cross the threshold. When

the threshold is set too low, the nerves become hyperactive and fire at the same

time. As this synchronized firing occurs across the brain, the body goes into an

epileptic seizure.

Neuronal gates called ion channels regulate the rest-excitement balance in each

cell. Sodium and calcium channels help to excite the cell, and potassium

channels suppress the signaling between cells which increases the threshold at

which nerves fire. Kv12.2 is active in resting nerve cells and is in brain

regions linked to seizures.

The scientists used an electroencephalography (EEG) device to monitor the brains

of mice, and found those without Kv12.2 had frequent seizures with no

convulsions, while normal mice had a higher convulsive seizure threshold. To

solidify their research even more, the scientists blocked the Kv12.2 gene in the

normal mice and had the exact same results.

" In mice without a functioning Kv12.2 gene, nerve cells had abnormally low

firing thresholds, " Jegla, an assistant professor of biology at Penn

State University, was quoted as saying. " Even small stimuli caused seizures. We

think that this potassium channel plays a role in the brain's ability to remain

'quiet' and respond to selectively strong stimuli. "

Researchers plan to continue to study whether activating the Kv12.2 gene in

normal animals can block seizures.

" Ion-channel defects have been identified in inherited disorders, but many types

of epilepsy don't have a genetic cause to begin with, " Jegla said. " They're

often caused by environmental factors, such as a brain injury or a high fever.

However, the most effective drugs used to treat epilepsy target ion channels. If

we can learn more about how ion channels influence seizure thresholds, we should

be able to develop better drugs with fewer side effects. "

Source: Penn State press release, August 1, 2010