--- > As far as a breeding program is concerned, what is the value of knowing if a dog is likely to produce DM or develop it in the future?

One day it will be of tremendous value- potentially- if enough $ goes into DM research, and people become proactive about ridding the breed of DM. However, right now, DM research is in its infancy...the test results, either test results, is information to process, along with the history in one's lines. We have major hurdles to cross, before we can become knowledgeable enough to know which dogs need to be eliminated from the gene pool. Personally, and I reiterate, PERSONALLY, I  would not breed a positive to a positive. There are enough dogs that test negative to avoid breeding 2 positives together. That doesnt mean a dog need be thrown out or eliminated from the gene pool- just not bred together- again, that just my humble opinion.

I knew you wouldnt be angry :)

--- >I saw that it said other tests should be done

Again, that is in a dog actively exhibiting signs of DM, so one can have a complete picture of what conditions are present and possibly going on simultaneously. For example- if a dog has DM, exercise is imperative. However, if that same dog has DM and a disk problem, the treatments would not be the same, as disk problems require rest and many times, surgery.  Long periods of inactivity are hell on wheels for DM dogs and can cause the disease to progress much more rapidly. Conversly, activity and exercise can be hell on wheels for dogs with disk problems...Thus, more extensive testing is required to make sure treatment can be done accordingly and that one can see the complete picture.

Marjorie
http://www.gsdbbr.org --> The German Shepherd Dog Breed Betterment Registry (including frozen/chilled semen database)
Please utilize this registry to ensure a healthy future for our breed!
Be PROACTIVE!
 http://mzjf.com --> The Degenerative Myelopathy Support Group

As a single dog owner of a neutered pet, I won't be able to make as big contribution to the research on this disease as I would like to. However, I've decided if Blitz is positive and/or does develop it, I will do all I can to help out by submitting samples. etc.. 

Here is a final thought for you. If the gene test’s advantage is that they can find the carriers as well as the hnomozygous dogs, then the predictive value of a positive test is only 3%. If they only report the homozgous dogs then the predictive value is 10% just like the DM Flash test. Neither test is a good screening test, but we have shown that the Flash test is a good diagnostic test in clinically affected dogs. If you can for about the same price have a clinical answer in 2 weeks as opposed to 3-4 weeks and get the answer from some who is trying to help you treat your dog with the best treatment known, which test would you run?

Marjorie
http://www.gsdbbr.org --> The German Shepherd Dog Breed Betterment Registry (including frozen/chilled semen database)
Please utilize this registry to ensure a healthy future for our breed!
Be PROACTIVE!
 http://mzjf.com --> The Degenerative Myelopathy Support Group

<<<If they only report the homozgous dogs then the predictive value is 10% >>

Sorry,  still having a hard time following..

When you say report homozygous dogs..  you mean dogs that are tested and are positive for two copies of the gene that is being associated with DM?

And then predictive value...   as in predicting which dogs will actually exhibit symptoms of DM down the road?   Ten percent of dogs that test as carrying two copies of the gene will develop DM later on?

And if it reports all dogs with either one or two copies of the gene,  then only 3% of them will come down with DM symptoms?

Is that correct or did I get it all mixed up? 

In my discussions with Dr Clemmons, he has told me that If carriers are detected and the incidence is 75% of the breed while only 2% get the disease, there is no way to eliminate the disease from the DM Flash test or the gene test alone. You would have to remove between 25 and 75% of the dogs; to prevent 2% from getting the disease. That is why continuing our DNA work looking at the other regions we have already demonstrated as associated with the disease is important. Only by finding the “imprinted” genes which allow the other genes to activate will we be able to find the dogs who will end up with the disease. Finding the DM Flash test or the gene test is just the next step in the process of understanding the disease and how to prevent or treat it. If the rest of the research is not done because everyone thinks this is the final piece in the puzzle, it will be a sad day for GSDs.

It is now suspected that the genetic switches for the polygenic groups responsible for these various genetic disorders are located in the "junk dna" also referred to as "dark dna".  There is not much being published about this dark dna now because there is a real scramble going on to discover and patent these gene switches which may be activated by environmental stressors.

LOL- yes, patent- its all about the Patents, to some, because

patents = HUGE $$$$$$$$$$$$$$$$!

By the way setting up the betterment registry is an excellent idea.  Hat's off to the fine folks who have taken on this great task which will help quality oriented GSD breeders worldwide.

GSDXephyr,

In discussions with Dr Clemmons I have learned that a test’s significance is not just based upon the sensitivity and specificity of the test, since the value of the test is also a function of the incidence of the disease in the population. So, some feel that the predictive value of a positive and predictive value of a negative test which accounts for both of these factors may be a better way to determine usefulness of a test. For a screening test to be useful, it should have a very high predictive value, the disease should have a treatment, and the test should be cost effective. Based upon these criteria, and particularly the lack of treatment and low predictive value of a positive test, no reasonable epidemiologist would recommend performing the DM Flash test or the gene test as a screening test. We do know that the DM Flash test is a good diagnostic test, but that is because the incidence of DM in clinically affected dogs is around 25%, not 2% .

I think that the DM Flash test only detects dogs with 2 copies of the gene (homozygous for the condition), but I cannot absolutely confirm that. I do not know if the gene test is designed to detect both heterozygous (carriers with a single copy) and homozygous (2 copies) or just the homozygous affected dogs like the DM Flash test. Either way, neither should be used as screening tests for the disease in normal dogs, because the number who will actually come down with the disease is only 10% of the homozygous affected dogs, at best. Over all only 2 % of GSDs get GSDM. However, probably 25% of all GSDs are homozygous for what we detect in the DM Flash test.

 On the other hand, almost 100% of the dogs who have GSDM are positive in the DM Flash test so that the presence of the homozygous trait does account for 91% of the reason why a give dog will develop GSDM. That is still only 2% of all GSDs.

 Statistics are hard to understand and easily to manipulate, but analysis of real data done without bias can provide important insights into the nature of a disease. You can’t change the facts, you can only change how you interpret them. “Data does not lie, only researchers!”

Marjorie
http://www.gsdbbr.org --> The German Shepherd Dog Breed Betterment Registry (including frozen/chilled semen database)
Please utilize this registry to ensure a healthy future for our breed!
Be PROACTIVE!
 http://mzjf.com -->