Researchers find gene behind rare form of epilepsy

February 29th, 2008 - 11:51 am ICT by admin  

Washington, Feb 29 (IANS) A gene prompting a particularly debilitating type of epilepsy besides engendering kidney failure has been identified by researchers. The new findings, which begin to “crack open the cell biology of the problem”, were made with the help of only three affected individuals.

“Many people will not have heard of this extraordinarily rare disease,” said Samuel Berkovic of the University of Melbourne, Australia.

Epilepsy affects two percent of the populace. The genetics behind the seizures are often complex.

However, progressive myoclonus epilepsies, which Berkovic said can be quite disabling and tend to get worse over time, usually have a simpler, Mendelian pattern of inheritance caused by a variety of single genes.

Action myoclonus-renal failure (AMRF) syndrome is a lethal inherited form of progressive myoclonus epilepsy associated with kidney failure.

Symptoms usually arise when people are between the 15 and 20 years with signs of kidney trouble or symptoms like tremors, seizures, and later other movement disorders.

Upon close inspection, the kidneys of those with AMRF show scarring and their brains show an unusual build-up of storage material.

“The recessive gene defect underlying AMRF was unknown,” Berkovic said. So, his team came up with a new one. They first identified three unrelated families, each with a member having AMRF.

They then used a modified version of “homozygosity mapping” to narrow the candidate regions of the genome down to places where both copies of a gene were identical in one inbred family. They then used affected and unaffected family members to narrow the hunt further.

Then, they took another “quick shortcut” to finding the culprit, Berkovic said. Using microarray analysis, which measures gene expression, they identified genes within the implicated region that were turned down in those with AMRF.

As luck would have it, mice lacking the gene had already been developed. Upon examination, investigators found inclusions in the animals’ brains and subtle abnormalities in their kidneys, reminiscent of people with AMRF.

The report has been published in the latest issue of the American Journal of Human Genetics.

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