CEA DNA test now available from Optigen

[Denise Wall]

The new CEA test is available. See:

 

http://www.optigen.com/

 

C. Denise Wall, PhD

ABCA Health and Genetics Committee Member

[Rebecca, Irena Farm]

Woo hoo!

 

Thanks to everyone on and off the Genetics Committee who worked hard to see this day. Say, Denise, who is that determined-looking and handsome Border Collie on the Optigen web page?

[Denise Wall]

Thanks, Becca.

 

I have no idea who took the picture or who the Border Collie is on the optigen site.

[Rebecca, Irena Farm]

My bad. Thought it looked like Kate.

[Tassie]

That article on the Optigen site is probably the best I've seen on CEA and its implications. (I have a particular interest since I have a very mildly affected CEA bitch - spayed for safety.)

[Eileen Stein]

Barb, I totally agree with you. I was impressed. It's a very accurate and easily understandable explanation.

 

This test enables a border collie breeder to absolutely avoid breeding pups with CEA, while still not losing the superior working genetics that dogs carrying the CEA gene may have, simply by making sure via the test that one member of the breeding pair is CEA Normal (i.e., homozygous for the normal CEA gene). That is a tremendous step forward in the interests of keeping both working ability and healthy eyes in our breed. It also makes it possible to move toward reducing the incidence of the CEA gene mutation throughout the breed, gradually over time, without sacrificing working ability. We are fortunate that CEA turned out to be caused by one specific mutation in one specific gene, and that the penetration of CEA in our breed is small enough that as a practical matter we don't have to worry about the modifier genes.

 

This is a happy day. Think I'll open a bottle of wine and drink to all the folks who made it possible.

[Northof49]

This test enables a border collie breeder to absolutely avoid breeding pups with CEA, while still not losing the superior working genetics that dogs carrying the CEA gene may have, simply by making sure via the test that one member of the breeding pair is CEA Normal

 

But if people are going to continually breed CEA carriers to non-carriers, you are going to once again increase the number of carriers into the population and decrease the number of non carriers.

 

One would hope that breeders would aim for breeding clear to clear, unless the carrier pups off such a mating are going to be altered.

[Eileen Stein]

That's not at all what I hope for the breeders of working border collies, Northof49. It would be a misuse of the test to immediately start using it as a litmus test for breeding -- breeding only clear to clear -- because eradicating the CEA gene from the gene pool is NOT the highest priority a good border collie breeder should have.

 

The wonderful thing about this test is that it enables us to tame this disease. Because it is now possible to breed so that no dog is affected with CEA, we have the luxury of taking our time to gradually diminish the percentage of border collies carrying the mutant gene. Why is gradual better than immediate? Because if we immediately went to breeding clear-to-clear only, we would lose from our gene pool all the good working genetics from the dogs who are not clear. We don't want to create a genetic bottleneck with only the CEA normal dogs passing through the narrow place. That would also tend to concentrate other undesirable recessives which we're not even aware of, as well as costing us in diminished working ability.

 

The ABCA Health & Genetics Committee is currently working on modifying its breeding guidelines with respect to CEA, and they will be posted on the ABCA website in the near future. I don't expect them to be greatly changed from the old recommendations; the test will just enable breeders to pursue the same goals with more precise tools. I expect they may recommend that if breeders have two or more dogs of equal suitability that they are considering for a breeding to their CEA normal bitch, they should opt for a CEA normal over one who is a carrier, but I am sure they will not recommend only breeding CEA normal to CEA normal. The "clear to clear only" approach might make sense in a breed where an appearance standard defines the goal, but we have too much to lose in our working breed if we were to take that approach.

 

If we make it a long range goal to diminish, and perhaps someday even eliminate, the CEA mutation from our gene pool, and if we adopt sound strategies to chip away at achieving that goal (by for example considering the CEA gene status of pups in a litter where only some are to be trained for stockwork in deciding which ones will go as pets and be neutered), we can, thanks to this test, have our cake and eat it too.

[Northof49]

The wonderful thing about this test is that it enables us to tame this disease. Because it is now possible to breed so that no dog is affected with CEA, we have the luxury of taking our time to gradually diminish the percentage of border collies carrying the mutant gene.

 

Eileen, I understand the benefits of being able to carefully map out breeding programs with the knowledge of CEA carriers, etc etc., because you can make better informed decisions about which way to go, but again breeding programs have to be planned into the future and very careful assessments done on each litter - that doesn't happen around here, it's very much only in the present.

 

It will be interesting to find out in the next 5 years how many people acually get their breeding stock tested. I know, unfortunately around here it won't be happening.

[Eileen Stein]

You may be right, North. I think everybody involved with this test has two fears -- (1) that the deplorably high cost may keep people from using it at all, and (2) that people may go overboard with it, simplistically rejecting pups or breeding stock who are carriers (much the way OFA ratings are misunderstood and misused in some quarters). Perhaps both things will happen, in different populations, thereby causing further divergence between working BCs and kennel club BCs. (Y'all know I'm in favor of increasing the separation, but not in this particular way. )

 

My hope is that everybody -- breeders, puppy buyers, and just people who care about the border collie -- will try to play a part in encouraging the intelligent, beneficial use of this test. We have a great opportunity here. Let's not just turn it into a little merit badge, distinguishing "good dog" (clear) from "bad dog" (carrier). In the here and now, a carrier is just as good a dog as a clear dog EXCEPT when it is bred without regard to the CEA status of its mate. If you're getting a pup you don't intend to breed, there's no earthly reason to prefer a clear to a carrier. There is good reason, however, to prefer a pup from a breeder who uses this test as part of his breeding program, to make sure his breedings contribute to the short-term and the long-term well-being of our breed.

[Denise Wall]

As one of the people involved since the beginning in promoting this research and the development of this test, I agree with Eileen that one of the fears has been inappropriate use. The education started years ago with the eye testing and updates in the ABCA newsletter and webpage. I think any of you who?ve gone to his talks or talked with Dr Acland at the finals can attest to his generosity in sharing his knowledge and his skill at educating people on eye diseases.

 

The CEA gene is only one of many disease-causing genes a border collie may carry. All animals have deleterious recessive mutations and the CEA mutation is a relatively mild one as these things go. Yes, CEA should be taken into consideration in a breeding, but it should be kept in perspective. CEA status is just one of the many, many things one should consider in planning a breeding of good working dogs. A CEA clear DNA test should NOT be used as a marketing tool or given more importance than it deserves.

 

As most of you know, dogs in the UK are not allowed to compete in sheepdog trials if they are CEA affected, and their papers are pulled if they produce CEA affected pups, that is, if they are found to be carriers by producing CEA. Before I joined the Health and Genetics Committee (called at that time the ABCA Eye Committee) eight years ago, the ABCA/USBCHA had adopted the UK policy of not allowing CEA affected dogs to run in the finals. One of the first priorities of the new committee was to de-stigmatize CEA affected dogs and carriers. One major step was to require all dogs running in the USBCHA finals to have eye tests, but they were not required to be clear of CEA to run. It was felt by the ABCA Eye Committee that the type of restrictions imposed by the UK not only drove the disease underground, making people afraid to acknowledge they had a problem in their kennel, but also kept them from seeking help on making informed breeding decisions. There is no evidence I know of that suggests the CEA carrier rate in the UK has decreased in all these years of restrictions. In addition, some very good working dogs were culled from breeding because they were shown to be carriers. The H&G Committee did not consider this a good outcome and wanted a more effective long-term plan.

 

Although, now, with the CEA DNA test, CEA carriers could very effectively be eradicated in just one generation, at what cost? In the US the carrier rate is suspected, based on the affected rate, to be around 25%. That is, on average, one in four dogs, or one of the dogs in every other breeding pair. That is an unacceptable number of dogs to lose from the gene pool even without consideration of the good working genes lost. A rule of thumb I?ve learned from population geneticists is carriers should not be banned from breeding with a DNA test if the carrier rate is above 10%. This is because it will adversely affect the gene pool with regard to health issues. And again, not to mention all of the good working traits lost when the carriers are banned. Clearly, by any prediction system, the CEA carrier rate in our breeding is higher than 10%. Therefore, carriers should be bred for the continued genetic health of the breed, just bred wisely.

 

I?ll end here by pointing out something concerning the cost of the test. Presumably both potential parents would have been eye tested so neither would be CEA affected. Only one of the breeding pair needs to be CEA DNA clear (no copies of the CEA gene) in order to not produce affected pups. In addition, if one parent has tested DNA clear, there is no need to eye test the puppies, since none will be affected. The cost of eye testing all the puppies is not that much less than one DNA test depending on how many pups you have and if the parent tested proved to be clear. So in the end the difference, if any, in cost, is not that great. And you wouldn?t have to worry about getting them to the eye vet before they were sold.

 

I?m sure I?ll have more to say later so I?ll end here before this gets too long.

[Julia Hunt]

Is anyone interested in trying to put together a '20/20 satellite clinic' ? It brings down the cost to $135 per dog. Each dog must have permanent id and a timeframe would be set within which we must all have the blood drawn and sent. We would need 20+ dogs, I have 2 to do.

 

Julia

[Eileen Stein]

I've been trying to keep up with what is being said about the DNA test on various lists and BBs, and I was very heartened to see that some of the most respected posters on the workingsheepdog list, especially on the continent, are really taking a sound position on how the test should be used and not abused. Maybe they will influence the ISDS away from excluding carriers.

[karrider]

I would hope that the ISDS will eventually allow dogs previously de registered to be used again,provided they are bred to DNA clear dogs then there is no chance of affected puppies. I think total eradication of CEA is probably going to be an unrealistic goal for the forseable future as there are always going to be the $$$??? hunters who choose not to test for anything at the present so will not bother with DNA testing anyway.

 

I think a first step of not producing any affected puppies is a good place to start.

regards karin