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Cardiology |
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| 15 Oct 2009 | Viewed: 41 | |
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The most common gene for a
syndrome associated with abnormal heart rhythms and sudden death
triggers epileptic seizures and could explain sudden unexplained death
in epilepsy, said researchers from Baylor College of Medicine in a report that appears today in the journal Science Translational Medicine.
The identification of this particular potassium channel KvLQT in
neurons of the central nervous system gives scientists a clue about
which epilepsy patients face the greatest risk of dying unexpectedly,
said Dr. Jeffrey Noebels, the study's senior author and director of the
Blue Bird Circle Developmental Neurogenetics Laboratory at Baylor
College of Medicine. The channel has been identified in heart muscle
cells and now for the first time in brain or nerve cells.
"Idiopathic (unexplained) epilepsy is one of neurology's
oldest mysteries. While most persons with epilepsy will have a normal
lifespan, our finding now points the way to a simple and essential test
to identify risk for sudden death in persons with seizures of unknown
origin. In these patients, a routine cardiology evaluation consisting
of an EKG, and if indicated, a genetic screening test for this family
of genes can positively identify this new risk factor," said Noebels.
"If the gene test is positive, there are effective treatments for the
heart irregularity, including drugs known as beta blockers, as well as
the use of a cardiac pacemaker to prevent lethal arrhythmias."
As many as 18 percent of deaths in epilepsy come suddenly without warning, devastating families.
"Living with epilepsy is difficult enough, but unexpectedly dying from
it, as happens in young adults with the disorder, is one of the
greatest fears a family must face," said Dr. Alica Goldman, assistant
professor in the BCM department of neurology. Noebels is a professor in
the departments of neurology, neuroscience and molecular and human
genetics at BCM.
No one knew why young people with epilepsy died suddenly, but
Goldman built on previous work in Noebels' lab that found that an ion
channel gene thought to work only in the heart was active in the brain
as well. She examined five ion channel genes linked to long QT
syndrome, a disorder associated with heart rhythm disorders and sudden
death.
Long QT refers to an interval in electrocardiograms - the QT
interval, which is prolonged in this disorder. An ion channel is a tiny
pore in a membrane that controls the flow of ions such as calcium and
potassium in and out of a cell.
Goldman found that mice with a mutation in the gene that
encodes for the KvLQT1 ion channel had frequent epileptic seizes as
well as life-threatening heart rhythm irregularities.
'This demonstrates the long-sought molecular link between heart and brain in epilepsy," said Noebels.
Goldman is now screening epilepsy patients to determine whether they have the same gene mutation.
Others who took part in this work include Ed Glasscock, Jong
Yoo, Tara Klassen and Tim Chen. Funding for the work came from the Dana
Foundation, the National Institutes of Health, the American Heart
Association, and Blue Bird Circle Foundation of Houston. An abstract of
the report is available at http://stm.sciencemag.org/.
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| News Source: medical news today |
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