following article appeared on
University of Guelph website on May 14, 2007:
Researchers Find Cause
of Muscle-Stiffness Disease
Imagine a dog running
after a ball, only to stiffen up and fall over because of
a genetic muscle cell disorder. It may sound almost comical,
but this disorder, called Myotonia congenita, affects dogs,
cats, horses, water buffalo, and even people.
Two University of Guelph
professors have found the cause of the disease that temporarily
prevents an animals muscles from relaxing after they
contract. The research by Andrew Bendall and Brad Hanna is
published today in the Journal of Veterinary Internal Medicine
In humans, so far more
than 80 mutations of the skeletal muscle chloride channel
gene (called CLCN1) - which temporarily prevents muscles from
relaxing after they contract - have been found. In animals,
scientists have barely begun to scratch the surface of finding
the causes of the muscle disease. Bendall and Hanna of the
Department of Molecular and Cellular Biology have discovered
the mutation associated with Myotonia congenital in Australian
Cattle Dogs and in a Maltese-cross dog.
"There are probably
eight breeds of dogs known to have Myotonia, but up until
our study, the Miniature Schnauzer was the only breed for
which a specific genetic mutation had been found," says
Adds Hanna: "I think
theres a misunderstanding among some veterinary practitioners
that once you find a mutation that causes the disease, thats
it. The human example shows us clearly that, no, in different
families there may be different mutations."
That means that even
though a blood test has been established to detect Myotonia
in the Miniature Schnauzer, its unlikely that it will
detect the disease in any other breed of dog. Because Bendall
and Hanna found the mutation in the Australian Cattle Dog,
they were able to develop a blood test to detect the disease
in that breed which is now offered at the provincial diagnostic
Animal Health Lab at U of G.
"We found that in
the Australian Cattle Dog its a truncation mutation,
so theres actually a portion of the skeletal muscle
chloride channel thats missing," says Hanna. "Eighty-eight
amino acids are missing at one end of the channel."
Bendall and Hannas
research will not only benefit the owners of Australian Cattle
Dogs, but "by identifying the kinds of mutations that
affect the function of the protein, you can lean something
about how the normal protein works," says Bendall.
The fact that Bendall
and Hanna have successfully cloned the CLCN1 gene in the Australian
Cattle Dog and found the mutation means that they are now
able to find mutations in other breeds more quickly.
Since their success in
Australian cattle dogs, theyve also discovered the mutation
in a Maltese-cross with a severe case of Myotonia. "We
have found a missense mutation, which results in the substitution
of one amino acid for another in the protein," says Hanna.
"That amino acid has not been found to be mutated in
this way in humans, so were in the process of doing
the functional work to determine the significance of this
When veterinarians diagnose
Myotonia in animals, since theres no known treatment
for the disease, they often dont refer clients to Bendall
and Hanna for testing.
"We would be interested
in hearing from veterinarians who have identified animals
of any breed or any species with a similar disorder,"says
Hanna. "Its possible, especially with purebred
animals, for this type of disease to become widely disseminated,
so by developing blood tests we can help breeders eliminate
following article appeared in
Practice News" 18(10):6, Oct 2006:
Available for Australian Cattle Dogs
Animal Health Laboratory at the Ontario Veterinary College,
University of Guelph, now offers a diagnostic restriction
fragment length polymorphism-based genetic test for whole
blood that can identify myotonia congenita in Australian
test can detect the defective allele in those that are affected
or a carrier.
proceeds from the test will be used to help W.J. Brad Hanna,
DVM, Ph.D., assistant professor in the Department of Biomedical
Sciences, and colleagues continue research to identify other
ion channel diseases of animals and to develop blood tests
to detect them.
more information visit www.ahl.uoguelph.ca.
following article appeared in
"Guelph Mercury", Apr 8, 2005, and "At Guelph",
May 4, 2005:
for a Calming Effect
Researchers tackle disease
that causes muscle spasms in animals
Prof. Andrew Bendall, left, graduate student
Dan Finnigan, centre, and Prof. Brad Hanna are studying a
muscle cell disease that can cause animals such as their canine
companion, Ally, to shake in place uncontrollably. Photo by
disorder that causes muscular spasms in many animal species
is under the microscope of Guelph researchers who want to
find the genes behind the disorder and methods to test for
them. Knowing its causes, they believe, will help eliminate
the disease through selective breeding.
Brad Hanna and graduate student Dan Finnigan of the Department
of Biomedical Studies and Prof. Andrew Bendall, Molecular
and Cellular Biology, are looking at domesticated animals
such as cats, dogs, horses and Brazilian water buffalo (a
food animal in its native country) to shed more light on myotonia
congenita, a genetic muscle cell disorder that temporarily
prevents muscles from relaxing after they contract. During
these episodes, which usually last less than a minute, the
animal shakes or shivers in place, unable to move.
the condition may be disturbing to a pet owner, it doesn't
seem to do any damage to the muscle, says Hanna, so it often
goes undiagnosed. But the problem is more serious in large
animals. Prolonged muscular rigidity causes the animals to
fall over as they try to move, which increases the risk of
injury to both the animals and the people working around them.
And it's undesirable in animal athletes such as race horses.
a race horse that is unable to move out of the starting gate
or cattle that stiffen and collapse when they're herded,
Finnigan are focusing on how myotonia congenita works at the
cellular level. In healthy animals, passageways in muscle
cell membranes called chloride ion channels act as conduits
for electrical nerve signals, which enter muscle cells and
tell them to contract or relax. But animals afflicted with
myotonia congenita have defective channels, causing muscles
to contract but not relax right away.
where Hanna comes in. He's studying the ion channel function
in animal patients suspected of having myotonia congenita.
Currently, Finnigan and Bendall are using molecular biology
techniques to look for mutations in the chloride ion channel
genes. If a mutation is found, the genes responsible for the
mutation are incorporated into cell cultures.
Hanna can measure electrical currents in these cells to see
whether the chloride ion channels are functioning properly.
If they aren't, that means he and his colleagues may have
found the mutation that causes myotonia congenita, which is
the first step toward stopping the disease.
and Finnigan hope their research will lead to the development
of blood tests for myotonia congenita, so breeders of cats,
dogs, horses and livestock can eliminate the disease from
their animals through selective breeding. As an added benefit,
the researchers can also learn more about the relationship
between structure and function of chloride ion channels in
normal muscle, which could be of use to other muscle research
in the future, Hanna says.
in this work are Profs. Joane Parent, Roberto Poma and Henry
Staempfli and graduate student Ronaldo da Costa, Biomedical
Sciences. This research is funded by the Morris Animal Foundation.
following article appeared in
"At Guelph", Aug 11, 1999:
at the End of the Channel
study malfunctioning ion channels to gain information
useful to pharmaceutical companies, geneticists
of G scientists are studing ion channel defects
causing various human and animal diseases. Pictured
with Smokey, an OVC research horse, are clockwise
from left: Prof. Henry Staempfli, Prof. Saul Goldman,
Prof. Brad Hanna, Prof. Chris Gray, Igor Tolokh,
George White and Hank DeHann.
BY DEAN PALMER/SCENARIO IMAGING
at the computer monitor in Prof. Chris Gray's
biophysics laboratory and you might be hard-pressed
to see the connection to studies of heart diseases
in a Toronto medical lab. But Gray and Prof. Saul
Goldman, Chemistry and Biochemistry, hope to see
their computer simulations help medical - and
veterinary - researchers develop treatments for
several diseases caused by ion channels gone awry.
colourful tableau on Gray's computer screen
simulates the workings of tiny passages in cell
membranes that serve as gatekeepers, passing
ions such as sodium and potassium into and out
of cells. By studying malfunctioning ion channels,
they hope to gain information useful to pharmaceutical
companies developing drugs for treating various
diseases or to gene doctors aiming to correct
the underlying hereditary defects.
cystic fibrosis patients, for example, defective
chloride channels interfere with the transport
of water across cell membranes, causing the
lungs to become clogged with mucous. And heart
disease is connected with malfunctioning sodium
and potassium ion channels. "Drug companies
are interested in developing drugs to fix the
problem," says Goldman.
Backx, a Guelph graduate in biophysics and veterinary
medicine who is now a faculty member at the
University of Toronto, says his research group
wants to learn more about the role of malfunctioning
potassium channels in heart disease. He hopes
to help pharmaceutical companies develop selective
drugs, especially compounds to treat heart arrythmia.
About 40 per cent of all heart disease patients
who die suddenly are believed to suffer from
abnormal heart rhythms.
a former student of Goldman's, says the Guelph
computer model is currently the only way to
simulate the workings of ion channel proteins
and the effects of altering their structure
and function. Noting that he recently received
funding from the Medical Research Council for
his research program, Backx says: "It's early,
but I think this has incredible promise. We
believe we're the first ones to try to combine
experimental approaches with the theoretical
approach developed by Guelph."
the long term, learning more about the genetic
underpinnings of ion channel diseases such as
cystic fibrosis might allow scientists to repair
the rogue DNA itself, says Gray. "Perhaps you
could put a vector into the lung with DNA to
generate properly functioning ion channels.
You could go in and fix the genes responsible
for constructing these bad channels."
and Goldman have spent four years studying how
one type of ion channel permits the passage
of potassium ions. The pair relies on theoretical
physics and chemistry and the use of computer
simulations to model the flow of ions through
channels and to study the microscopic workings
of ion channel proteins. Also involved in their
work are research associate Igor Tolokh and
graduate students Hank DeHann and George White.
researchers expect to benefit from a group grant
approved last month by the Medical Research
Council for the U of T-based Membrane Biology
Group, to which they belong as co-investigators.
Hanna, another OVC and biophysics graduate who
worked with Backx in Toronto, says that kind
of basic research is central not just to studies
of human disease but also to certain veterinary
disorders. He points to his work with Prof.
Henry Staempfli, Clinical Studies, on a particular
genetic disease that results in defective sodium
channels in the skeletal muscles of horses.
hyperkalemic periodic paralysis (HPP), the rare
condition causes muscular weakness that can
lead to collapse, paralysis or even death. Paradoxically,
it increases muscle mass in quarter horses,
the very trait that makes them prize candidates
for the show ring (the disease is also called
Impressive Syndrome after an award-winning stallion
whose descendants have also been afflicted with
it). HPP also occurs in humans.
selecting for the most muscular quarter horses,
breeders were unwittingly selecting for the
sodium channel mutation causing HPP," says Hanna,
who first pinpointed the cause of the disease
in a paper written three years ago while completing
his PhD with Prof. George Renninger, Physics.
chance meeting had brought together the graduate
student's expertise in studying sodium channels
with Staempfli's puzzlement over abnormal electrical
activity in the skeletal muscles of quarter
horses. Hanna suggested that sodium channels
were failing to inactivate properly, which was
subsequently proven by his and Backx's research.
"I'll never forget, three o'clock in the morning,
looking at the oscilloscope and thinking: 'This
is the first time anyone has ever seen evidence
for a sodium channel disease.'"
Hanna began his doctorate, only one ion channel
disease - a disorder in a calcium channel in
people and pigs - had been found. Since then,
scientists have uncovered dozens of human ion
channel mutations that underlie diseases in
heart, brain, muscle and other tissues.
in ion channel diseases has exploded over the
last decade," says Hanna, who spent a year in
private practice but has recently returned to
Guelph hoping to study possible links between
sodium channel defects and "tying-up," the most
common form of muscle disorder found in horses.
following article appeared in
the "Guelph Mercury", Jan 9, 1997:
paralysis -- a mystery no more
mystery of a potentially fatal equine disease has been
researchers at the University of Guelph.
Brad Hanna, Biophysics, and his colleagues have discovered
the exact cause of hyperkalemic periodic paralysis (HPP)
or "Impressive Syndrome" (named
after an award-winning Quarter Horse which first displayed
signs of the disease). Hanna
made the discovery while fulfilling his Ph.D. with the
help of researchers in several
departments, including OVC and physics.
got involved with this project because I wanted to combine
the knowledge I've
gained from previous degrees in biophysics and veterinary
medicine by relating a
clinical disease to its physical causes at the molecular
level," Hanna explains.
is a genetic disorder which affects both humans and
horses. Since first showing up in Impressive, it’s
been passed through his lineage to thousands of
other horses. Impressive and his descendants are prized
for their excellent musculature...but
ironically, that's a signature of the disease.
is a problem because the skeletal muscles of afflicted
horses often stiffen
or relax involuntarily. The nerve cells of an HPP horse
send a signal to the
muscle cell telling it to contract... but the cell tries
to contract many times.
to Hanna, HPP foils the mechanism by which a normal
keeps messages from repeating themselves. This can cause
sudden paralysis, weakness, collapse and even death
thought the problem might be related to sodium channels.
All muscle cells
have sodium channels in their membranes which let sodium
in and out of the
cell. When an electrical signal arrives at the muscle
cell from a nerve, the
change in voltage opens the sodium channel, and sodium
flows into the cell. This
is part of the chain of events which cause the muscle
cell to contract. In normal
cells, the channel immediately shuts. Hanna wanted to
find out what was
happening in the sodium channels of horses with HPP.
cell cultures and recombinant DNA, he found that in
cells with this
genetic defect, the sodium channel's ability to shut
itself off is impaired. Since it
doesn’t shut immediately like a normal channel,
it results in the production of
many electrical signals when there should be only one.
Hanna worked closely
with Dr. P.H. Backx of the Toronto General Hospital,
another graduate of
biophysics and veterinary medicine at Guelph.
also used cell cultures to determine if drugs like anaesthetics
anti-epilepsy medications could make the sodium channels
work normally and
prevent the symptoms of the disease. So far, it seems
that these drugs are able
to restore the functioning of the channels almost to
owners currently depend on indirect methods to treat
HPP," says Hanna.
that we know the exact cause of the problem, we hope
that people may
be able to treat the disease more directly."
had the financial, laboratory, and intellectual support
researchers: Profs. George Renninger of Biophysics,
Henry Staempfli of Clinical
Studies and Jill McCutcheon of OVC.
research was sponsored by the Medical Research Council,
Natural Sciences and Engineering Research Council, Dynasty
Trust, and the Muscular Dystrophy Association of Canada.
updated May 14, 2007