Parkinson's
Disease: from dogs to humans
Julia Shuck, posted Oct. 31, 2006
His
curly hair bounced around as he walked like a goose in the
front, with his pelvis wondering from side to side. While
attempting to focus, he started to shake uncontrollably. Elvis,
a 4-month-old old Kerry Blue Terrier from Canada, owned by
MU Professor of Veterinary Medicine Dennis O’Brian,
is suffering from hereditary Cerebellar atoxia, a movement
disorder, caused by brain dysfunctions. Cerebellar atoxia
is the equivalent of Parkinson’s disease in humans,
only it has a juvenile onset which occurs earlier in life
for dogs than it does for humans. Canine Genomics was the
topic for Saturday Morning Science on Oct. 28, which was held
in the Life Sciences Center.
O’Brian began his studies in canine genomics over 15
years ago when Duke, a 6-month-old English Pointer came into
his veterinary office. Duke’s owner brought him in because
he wasn’t field training like normal dogs would. He
was becoming clumsier during training instead of steadying
himself, as he should have been. After testing Duke, O’Brian
told the dog’s owner that Duke was suffering from hereditary
Cerebellar atoxia. Duke’s owner posed the question to
O’Brian, “What good is a pointer that can’t
point?”
O’Brian explained to the audience how traits are inherited
and gene sequencing. A human will have the same genes that
a mouse or a dog will have; the genes are just in different
orders and may affect each creature differently. Scientists
have used the humane genome sequence and the mouse genome
sequence to help figure out the different sequences in canines.
Dogs are the sixth species to have their genome sequenced.
Dogs have 39 pairs of chromosomes and 20,000 genes while humans
have 23 chromosomes and 32,000 genes.
The Parkin
protein, similar in both dogs and humans, tags abnormal proteins
to indicate that they are bad and need to be cleaned out of
the cell. When a mutation occurs in the Parkin protein, the
mutated or “blind protein” doesn’t tag bad
cells that begin to build up and start to negatively affect
the cell’s ability to do its job. This leads to Parkinson’s
disease, a neurological disease where the brain is degenerating.
The Parkin gene, which when mutated causes Parkinson’s
disease, is the third largest-known gene.
When
scientists removed the PARK2 gene from mice, they went about
their lives as usual, with no effect from the removed gene,
showing the difference between mice and men. Because of domestication,
dogs have evolved with humans and sharing the same environment,
having similar social structures and diet.
Even
if a pointer isn’t able to point, dogs with Parkinson’s
can help other dogs by helping to locate carriers of the disease
so that they are not bred and their mutated gene passed on.
They can help humans by locating genes and their genetic diseases,
such as Parkinson’s disease. “More importantly
we can understand gene processes,” O’Brian said.
“By studying the genes in dogs, we can get a look at
the genes in humans.”
“In
one year [Elvis] will be unable to move, become unstable,
fall any time he tries to take a step and I will euthanize
him,” said O’Brian. O’Brian intends on euthanizing
Elvis before the dog can no longer walk, in order to allow
him to lead the fullest, happiest life with as little pain
as possible.
The lecture
on Canine Genomics was recorded and will be available on the
Internet by visiting the Saturday Morning Science Web site.
Next week’s Saturday Morning Science Lecture will continue
the topic of gene therapy by proceeding into stem cell therapy.
