DM information from Dr. Coates - Page 2

I shouldn't have said it isn't the right gene. Instead I should have said due to the 90% fox terriers with the gene and none ever having DM, it is probably several genes associated. I can't even go so far as to say environmental considering the data on fox terriers, who do often live to be 15-17 years old. Sort of blows the longevity aspect out of the research. Either fox terrors have a gene that protects them against getting DM. Which could be utilized in a cure if discovered. Or most breeds have another mutated gene that triggers the onset of DM. Gwen

I agree Abby. I used the wrong wording and realized after the fact. I am not genecist. Sorry about phrasing my post erroneously. Gwen

And the beat goes on..............

The OFA web site has been updated to state that there have been two dogs that were normal/normal on the test that were diagnosed with DM. So we know that the UM test does not cover all forms of DM. http://www.offa.org/dnatesting/dmexplanation.html Note that the test is now described as being for the most common form of DM. That means the most common form across all dogs. Another form *may* be more common in a particular breed. Of the two dogs one was a Bernese Mountain Dog that was homozygous for a different SOD1 mutation. The other was my GSD. He had the normal form of the SOD1 gene. The genetic cause of his DM is unknown but UM is working on it. So we know that there is a second form of DM that occurs in GSDs and is not detected by the OFA/UM DNA test. The form of DM detected by the test does not affect the sensory nerves very much. My GSD had an almost complete loss of sensation that progressed with the paralysis. I have talked to several other GSD owners whose dogs showed a similar profound, prgressive loss of sensation. I have been in correspondence with researchers at UM. They are very interested in tracking down this alternate form of the disease. If you have a dog with DM who shows a profound and progressive loss of sensation please have him/her tested. If the result is normal/normal please contact Liz Hansen at UM immediately.

DSurber,
Do you have an opinion on whether the current OFA (UM) DM test is worthwhile for breeders?
--Mary

This is just my opinion. Coates says the form of DM detected by the test is similar to human ALS. ALS does not cause severe sensory problems. Many GSD owners report that their DM affected GSDs show profound, progressive loss of sensation. There has been at least one GSD that showed those symptoms and was normal/normal on the test. So the test coming back clear does not mean a particular GSD can't get DM or can't pass DM on to his/her progeny. Anecdotal evidence suggests that this other form of DM is not rare in GSDs. On the other hand, UM has shown that the SOD1 mutation they test for is present in GSDs. I'm pretty sure but don't know that mutant/mutant GSDs can develop the "common form" of DM. The OFA test would help breeders avoid producing puppies at risk for the "common form" of DM but it will not do anything about the other form of DM. If you breed you may want to test your breeding stock. If one of the parents in every litter is normal/normal you won't produce any puppies that are at risk for the "common form" of DM. That is probably a good thing. I would not remove mutant/normal or even mutant/mutant dogs from your breeding program for that reason alone. It should be just another thing to consider. But if I were to breed such a dog I would only breed him/her to a tested normal/normal dog and I would test every puppy of such a breeding. However, even though you test every dog in your program you cannot say your dogs are free from DM. I've heard of some breeders doing that. They should stop. We now know different. We need to track down the other form of DM. To do that UM needs to find more normal/normal dogs with DM. If you have a DM affected dog please get him/her tested. Douglas

Just wanted to offer a comparison. There is a disease in horses called EPSM or PSSM. Researches found that you have to test for this disease in two ways. Some horses carry the genetic link to the disease and can be tested by DNA. Others, however, will have the disease but not genetic carriers. A muscle biopsy is required to test for and find the disease in these horses.

My guess is that DM is the same way. Perhaps some dogs carry the DNA link to develop DM, but other perhaps do not - yet still develop the disease.

This is just pure speculation on my part, but I assume the DNA alleles that researchers say carry DM are probably just triggers that may or may not go off ... not what does or does not cause the DM. Sort of the like HPV virus in women. The dogs probably come into contact with the disease at some point which triggers certain alleles and causes the mutation and the disease to develop. My best guess is that the German Shepherds who carry the SOD1 are probably more easily effected by DM, but this does not mean they will or will not develop the disease. Just like dogs without SOD1 are probably less likely to develop DM, but this does not mean they won't.

That's just my guess on the situation. For some reason, whatever actually causes DM is not something Fox Terriers carry. 

You assume there is one cause for DM with multiple triggers. This is likely not the case. Ther are most likely multiple causal chains that result in the collection of symptoms we call DM. This is suggested by the differences in sensory impacts between the common form and at least one alternate form of the disease. The biology of the two forms is clearly different.

Thank you DSurber for the thoughtful post, and for taking the time to follow through on the information from your dog.
What you wrote, has been my thoughts regarding this test. I had been planning to test possible breeding dogs, for my own information, and will go ahead with that plan. My test kits did not come from OFA, but a separate lab. Cannot imagine that will make any difference.
---Mary

Conversely at this time the www.offa.org/dnatesting/dmexplanation.HTML does not address the 5 "carriers" with confirmed DM. In fact the link claims there have been NO carriers with confirmed DM. I have spoken with Liz Hansen and emailed Dr. Coates and Dr Tonomura. There has been 2 GSD carriers with confirmed DM upon necropsy 2 Bernese Mountain Dogs with cinformed DM upon necropsy 1 Chesapeake Bay Retriever. Why does the link say NO carriers? This is very misleading to the general public. The Bernese Mountain Dogs have been known about for over 1 year. Why is the correct information not being made public? Very confusing. Gwen