Degenerative Myelopathy and Lou Gehrig’s Disease
Today Genetic Enginerring & Biotechnology News reported that researchers from University of Missouri and the Broad Institute have discovered that the genetic mutation responsible for degenerative myelopathy (DM) in dogs is the same one that causes Lou Gehrig’s disease (amyotrophic lateral sclerosis or ALS) in humans.
“We uncovered the genetic mutation of degenerative myelopathy, which has been unknown for 30 years, and linked it to ALS, a human disease that has no cure,” said Joan Coates, a veterinary neurologist and associate professor of veterinary medicine and surgery in the MU College of Veterinary Medicine. “Dogs with DM are likely to provide scientists with a more reliable animal model for ALS. Also, this discovery will pave the way for DNA tests that will aid dog breeders in avoiding DM in the future.”
That DNA test would be a blessing. Six years ago we had to let our Aussie Roo go when DM completely robbed her of the strength and agility she was known for in her youth. Words can’t describe how difficult it is to watch your dog get weaker and less coordinated every day — and worst of all, to be utterly helpless to stop it.
DM and ALS are progressive neurodegenerative diseases that affect nerve cells in the brain and the spinal cord. As the motor neurons atrophy and harden, muscle weakness occurs, especially in the arms and legs. As the disease progresses and motor neurons die, all ability to initiate and control muscle movements is lost.
There is no cure for either disease and DM typically progresses so rapidly that most dogs are euthanized within a year of diagnosis.
Comparative medicine is the study of the similarities and differences in disease patterns in different mammals. Dogs are particularly useful to study because they share our environment, and are similar to us in body size. Parallels in the diseases that affect humans and our dogs can provide benefits to both species. Studies conducted on dogs can help develop treatments and genetic screening tests for humans — and these drugs and tests can also be used to improve the health of dogs.
Previously, ALS research has relied heavily on transgenic rodents that expressed the mutant human gene SOD1, which causes ALS. Researchers found that dogs with DM also had mutations in their SOD1 gene. Many rodent models possess very high levels of the SOD1 protein that can produce pathologic processes distinct from those occurring in ALS patients. Since the SOD1 mutation is spontaneous in dogs, the clinical spectrum in dogs may represent more accurately that of human ALS.
“Compared with the rodent models for ALS, dogs with DM are more similar to people in size, structure and complexity of their nervous systems, and duration of the disease,” said Gary Johnson, associate professor of veterinary pathobiology in the MU College of Veterinary Medicine. “The results from clinical trials conducted with DM-affected dogs may better predict the efficacies of therapeutic interventions for treating ALS in humans.”
The staff at the Broad Institute are doing some wonderful work in conjunction with the canine genome project. Please visit their website and, if your dog is eligible, consider participating in their research. They need DNA samples from both healthy and diseased dogs and they can’t do this work without our help.
We gave them blood samples and other information when Zorro died last spring – the old man’s many health problems made him particularly interesting to them. They were kind and helpful, sympathetic to our loss and generous in the help they provided our vet. Knowing that the information they got from his DNA might help cure or prevent the diseases he suffered from was one small comfort we could take in that difficult time.
The cost of a blood draw is small is tiny compared to the great good it may do. Be generous. That blood might help save the life of a dog – or person – you love someday.