Researchers ID Gene Behind Rare Form of Epilepsy

Findings 'crack open the cell biology' of lethal inherited syndrome

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THURSDAY, Feb. 28 (HealthDay News) -- A gene mutation associated with a rare form of epilepsy that also leads to kidney failure has been identified by Australian researchers, who said the findings "crack open the cell biology of this problem."

They developed a new method to conduct a genetic analysis of three people with action myoclonus-renal failure (AMRF) syndrome. Symptoms of this lethal inherited form of progressive myoclonus epilepsy usually appear between the ages of 15 to 25. Symptoms include kidney trouble or neurological symptoms such as tremors, seizures, and eventually other movement disorders.

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The kidneys of people with AMRF show scarring, and their brains have an unusual buildup of storage material.

In this study, the researchers identified a mutation that affected a gene called SCARB2/Limp2 in the three AMRF patients. This gene is active in a wide range of tissues, where it's found on the surface of cellular components called lysosomes, which play a critical role in the breakdown of spent parts inside cells, a process called autophagy.

When they examined mice that lack the gene, the researchers found brain and kidney abnormalities similar to those seen in people with AMRF.

More research is needed to determine exactly what happens in people who lack this gene, but the researchers have some theories.

"SCARB2/Limp2 might have a role in physiological autophagy, and its deficiency could thus lead to accumulation of normally recycled proteins or organelles manifesting as inclusions (in the brain)," researcher Samuel Berkovic, of the University of Melbourne, said in a prepared statement.

The study was published online Feb. 28 and in the March 7 print issue of the American Journal of Human Genetics.

"Many people will not have heard of this extraordinarily rare disease. Nonetheless, the findings speak to the power of genetics to solve even quite rare problems," Berkovic said.

More information

The Epilepsy Foundation has more about epilepsy.

-- Robert Preidt