New cause for Progressive Myoclonus Epilepsies (PME) has been identified.

     One of the most devastating forms of epilepsy is progressive myoclonus epilepsy. An team of researchers have discovered a new gene that causes this type of epilepsy. It was shown that a single mutation in a potassium ion channel is the main reason for this disease. Researches at University of Helsinki, Finland and Universities of Melbourne and South Australia have identified a new gene for a progressive form of epilepsy. 

     Progressive myoclonus epilepsies (PME) are rare and inherited. They are usually childhood-onset neurodegenerative diseases. The goal of the study was to identify underlying genetic causes in 84 PME patients. They did so using DNA sequencing targeting the protein coding elements of the human genome. A genetic diagnosis was found for 1/3 of the unsolved patients. The most successful finding from the study was that a single mutation in a potassium channel encoding gene (KCNC1) is the cause for a large number of unsolved PME patients. They found that there was a mutation was found in 13 patients that were not inherited from parents, as usual. It had emerged in a germ cell of one of the parents or in the fertilized egg. It was found that each of the 13 patient had dozens of these new mutations, however, they are rarely disease causing. The researchers estimate that this mutation occurs in roughly 1 out of every 5.7 million, being very rare. However, with such a large population on earth, t at least hundreds of people could have this mutation globally.

     "A fascinating aspect of this finding is that this single mutation can be found in several patients all over the world. The mutation site is an example of a 'mutation hotspot' of the genome - a DNA nucleotide which is more prone for alterations", says Professor Anna-Elina Lehesjoki, the corresponding principal investigator of the study in University of Helsinki and Folkhälsan Research Center, Finland. "The fact that the mutation occurs in a well-characterized ion channel gives hope to development of targeted therapy. There are anti-epileptic drugs in the market that target other similar ion channels and follow-up research aims to discover a way to rescue the function of the channel in PME patients."

     The mutation disrupts the function in a potassium channel, which has a central role in signal transmission in the brain. The mutation causes in inhibitory signals in certain parts of the brain to be reduced, which makes patients more susceptible to epileptic seizures and myoclonus in early childhood stages. The mutation also causes degeneration of the cerebellum and subtle cognitive decline.

     I think these findings really bring epileptic studies a long way. The knowledge they now have could potentially aid in diagnostics and potential therapeutic medications for the disease. The study also proved how significant DNA technologies are and how powerful they are in understanding the underlying genetic causes of severe diseases.

Article: http://www.medicalnewstoday.com/releases/285642.php

octopus from the Arctic tweaks its RNA to make nervous system proteins that work better in the cold.

To endure the cold, octupus living in the freezing cold waters o the Antarctica use a trick called RNA editing to produce proteins that work that work at low temperatures. The proteins excreted by the nervous sytem to send signals don't work efficiently. After a nerve cell fires and the electrical charge across the cell membrane comes to normal, the potassium ions are shut out out of the ion channels but at cold temperatures the potassium channel's closing can be delayed thus slowing down the neuron. Researchers thought that animals living in these cold temperatures might have modified their postassium channels so they work better in the cold. 



 Molecular neurophysiologist Joshua Rosenthal of the University of Puerto Rico Medical Sciences Campus in San Juan and his graduate student Sandra Garrett figured they knew how that adjustment would occur. "We thought we were going to see changes at the level of the gene," Rosenthal says. But instead they use RNA editing, to change a protein. During RNA editing, cells change the nucleotide sequence of the RNA which changes the sequence of amino acids in the resulting protein and change the protein's function. The Antarctic octopus edits its RNA at nine sites that change the amino acid sequence of the potassium channel.

Other researchers praise the study for revealing a new way for organisms to adapt. "There's this whole different molecular mechanism for increasing protein diversity," says molecular neurobiologist Ronald Emeson of the Vanderbilt University Medical Center in Nashville.