# New DNA-Marker Health Test Available for APBT's



## CCaragan (Oct 16, 2009)

I am very excited to announce a new health test for Cone-Rod Dystrophy (day blindness) through Optigen. This test has become available as of last week. I have been directly involved in this program with Cornell university for the last 11 years. Here is the info below any questions feel free to contact me.

By having the courage to discuss health issues with purebred dogs, helps that community to have tests become available. With modern day research in DNA we now can have DNA-markers for recessive health issues. Having a DNA marker is not subjective, it is definite. As a community of dog fanciers we need to come together to help each other, by being open and honest, not judgmental to help our beloved breed.

Also I am putting together a sample research collection test for 20 different strains of APBT bloodlines to be tested at a discounted rate What I am looking for is totaly non-related APBT's lines with no grandparents in common then we could begin to get an idea of the crd2 mutation's distribution in the APBT population. I need tight bloodlines for the tests, with little to no Amstaff in the lines, if you read below Amstaffs are affected by CRD1 and they do not have the marker as of yet for them, but can be tested upon request. This recessive gene is not specific only to my lines, but all APBT's.

During my involvement with Cornell University with my bloodlines, I was informed that they had ADBA/APBT's-UKC/APBT's-AKC/Amstaffs in the research program that were affected by Crd, but bloodlines were kept confidential. To my knowledge this research has been going on for 15 + years, and thanks to Morris Animal Foundation for funding the grants for research.

CRD 2 MutationTest for American Pit Bull Terriers
Cone Rod Dystrophy 2 (crd2) in the American Pit Bull Terrier

June 16, 2010

Announcing the crd2 mutation DNA test in the American Pit Bull Terrier (APBT): OptiGen is pleased to provide a new DNA test that detects the presence of a mutation causing an inherited eye disease, Cone Rod Dystrophy 2 (crd2), in the American Pit Bull Terrier.

What is crd2? crd2 is one of several cone rod dystrophies that have been recognized in multiple breeds of dogs. All forms of CRD are characterized by the initial loss of cones, the cells in the retina that are responsible for vision in bright light/daylight, followed by the degeneration of rods, the retinal cells that operate during night vision. Clinical symptoms of crd2 are typically evident early in a pup's life and the severe retinal degeneration that characterizes this disease usually results in complete blindness by 1 year of age.

What breeds of dog carry crd2? To date, the mutation causing crd2 has only been observed in one breed of dog, the APBT. Researchers were somewhat surprised to learn that this mutation was not the cause of a very similar disease that occurs in a closely related breed, the American Staffordshire Terrier (Am.Staff.). The Am.Staff.'s disease has been termed Cone Rod Dystrophy 1 (crd1) and is currently being molecularly characterized. Because Pit Bulls and Am. Staffs share many common ancestors and interbreeding among these and other bull-type dogs is quite common, OptiGen will accept samples from any of the "bull" breeds for crd2 testing. It should be emphasized, however, that there is currently no evidence to suggest that crd2 is present in any breed besides the APBT. Owners of pedigreed dogs that have been diagnosed by a veterinary ophthalmologist as having retinal degenerations (e.g. PRA or CRD) are encouraged to contact OptiGen to inquire about our Free DNA testing/Research program (OptiGen - Research).

How is crd2 inherited? How should I use the DNA test? crd2 is inherited in an autosomal recessive mode, meaning that offspring need to inherit the mutation from both parents (i.e. have two copies of/be homozygous for the mutation) for disease to occur. Carriers of one copy of the mutation (heterozygotes) will not show disease but they can pass the mutation on to their offspring. The great value of the DNA test is that it will allow detection of Carriers. In order to avoid producing crd2-affected offspring, carriers of the mutation should never be bred to other cd2-carriers. In other words, at least one of any breeding pair should be homozygous Normal/Clear of crd2 to ensure that no crd2-Affected offspring are produced. (See chart below.)

Expected results for breeding strategies using the
OptiGen crd2 test
Parent 1
Genotype
Parent 2 Genotype
Normal/Clear Carrier Affected
Normal/Clear All = Normal/Clear 1/2 = Normal/Clear
1/2 = Carrier All = Carrier
Carrier 1/2 = Normal
1/2 = Carrier
1/4 = Normal/Clear
1/2 = Carrier
1/4 = Affected 1/2 = Carrier
1/2 = Affected
Affected All = Carrier
1/2 = Carrier
1/2 = Affected All = Affected

This table highlights in yellow the desirable breedings that will NOT produce crd2 -affected pups. These breedings include at least one parent proven "Normal/Clear" by the OptiGen crd2 test. All other breedings are at risk of producing crd2-affected pups. With the aid of DNA testing, all dogs, even those carrying the crd2 mutation, can be bred with complete confidence that no crd2-affected pups will be produced. It isn't necessary-or even desirable-to remove any dog from the breeding population. Rather, when choosing pups to retain as potential breeding stock, one may select for dogs proven "Normal/Clear" by the OptiGen crd2 test, and select against dogs proven to be carriers. In this way, breeders can retain desirable traits in their lines while moving away from disease. Pups can be tested to distinguish carriers from Normals as soon as they are old enough to have a small blood sample or non-contaminated cheek swab collected.

How do I get my dog's DNA tested for crd2? To test your dog's DNA for crd2 please see OptiGen's Instructions & Information webpage (OptiGen - Instructions and Information). Complete an order form and send either a cheek swab or whole unclotted blood in EDTA to OptiGen. Tests are typically reported within two weeks of OptiGen's receiving the sample. Contact [email protected] with any questions.

Research leading to the discovery of the crd2 mutation was conducted at Cornell University and the University of Pennsylvania, with collaboration by OptiGen.

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## geisthexe (Jan 18, 2007)

Thats is GREAT news about this new DNA they can do. 
I would also like to commend you for being apart of it. 

Thanks for sharing and I hope folks w/ the breed take up on this to provide good healthy dogs.


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## CCaragan (Oct 16, 2009)

Thanks Deb,

It takes courage to talk about health issues in pure bred dogs, on the average every purebred dog carries 4-5 recessive genes for health issues and that is a low # for some breeds. Regular health testing is a tool to be used, most of which is subjective to a lot of things, however DNA markers are finale. I feel very blessed that Cornell was able to find a DNA marker for APBT CRD2, at one point they ran out of money and the program was on the shelf for several years. So it takes breeders to donate affected dogs & grants for research.


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## Indigo Bully Connection (Dec 21, 2006)

Silly question, but what do you mean that they don't have a "marker" for am staffs? This is extremely interesting and I'd like to participate, but my dogs have a lot of Am Staff


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## CCaragan (Oct 16, 2009)

According to Cornell the gene is mutated in the Amstaffs and for what ever reason they have not found the DNA marker for CRD1 for the Amstaffs as of yet. Amstaff breeders need to test their dogs and send in affected dogs for research. Optigen also offers free testing for affected dogs.

Researchers were somewhat surprised to learn that this mutation was not the cause of a very similar disease that occurs in a closely related breed, the American Staffordshire Terrier (Am.Staff.). The Am.Staff.’s disease has been termed Cone Rod Dystrophy 1 (crd1) and is currently being molecularly characterized. Because Pit Bulls and Am. Staffs share many common ancestors and interbreeding among these and other bull-type dogs is quite common, OptiGen will accept samples from any of the “bull” breeds for crd2 testing.


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## CCaragan (Oct 16, 2009)

This eye disease is not easily detected as the pups are born able to see in low light levels, most pups are kept inside until they go to their new homes. Most would consider it puppy clumsiness, not knowing about the disease to begin with. In bright light they run into things. As far as recessive diseases I would take this over many other recessive genetic diseases if I had a choice, because it is onset from birth, when many other disease's creep up in later years.

In a perfect world we would all be perfectly healthy


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## bluefamily (Aug 8, 2007)

very cool just the type of information that is so important to pass along on these boards. thanks so much!!!


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## CCaragan (Oct 16, 2009)

Hi Blue Family,

It is nice to hear positives, since so many individuals from the beginning of the discovery of this problem in Lar-San lines were all over forums bashing, but never becoming part of the solution only the problem. It's a wonder most people will not talk openly on important issues concerning pure bred dogs. I can say from personal experience sending my affected pups to a colony for research was very difficult, but it was the right thing to do to help my dogs as a whole. There are only 3 of us that participated with the Lar-San lines Sandy Comer, Kim Allison and myself that I know of, and for our participation I feel we now have this test today.


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## Patch O' Pits (Aug 3, 2007)

That is great news!


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## CCaragan (Oct 16, 2009)

CRD2 was no secret and I was vocal with everyone that had the lines on coming together in breeding away from it when no test was available and preserving these lines and or contributing to research. Keeping records on dogs that had produced affected, who was a carrier etc. I put it out there to the other breeders, they chose their own path.

This test in my opinion is huge for the canine APBT community, eventually someday they will have DNA markers for canine cancer, hip dysplasia, heart problems etc. The upside to finding the DNA marker for CRD2 was there were only a hand full of genes that cause it, vs other recessive diseases like PRA it could be thousands of genes the researchers have to sift through taking years to discovery.


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## Indigo Bully Connection (Dec 21, 2006)

Cheryl, I've been meaning to thank you for my dogs and family for the last few months. I know that was off topic, but i needed to do it. 

do you have any idea when this study will start opening for more than just the APBT? I mean like GSD, labs, collies ect?


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## fortyfootelf (Feb 2, 2010)

this is awesome. thank you is all i have to say. this has been a problem with APBT's and im sooo glad that there is light at the end of the tunnel


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## aimee235 (Apr 29, 2007)

That's cool!


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## dixieland (Aug 14, 2009)

Yes thanks for the info and thanks to everybody that's participating!


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## performanceknls (Apr 4, 2009)

Indigo Bully Connection said:


> Cheryl, I've been meaning to thank you for my dogs and family for the last few months. I know that was off topic, but i needed to do it.
> 
> do you have any idea when this study will start opening for more than just the APBT? I mean like GSD, labs, collies ect?


This is a mutation that has only effected APBT's and has not been identified in any other breed.


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## bahamutt99 (May 14, 2008)

I read something a long time ago that said it was identified in Malamutes, too, but I couldn't tell you where now. Sorry.


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## performanceknls (Apr 4, 2009)

bahamutt99 said:


> I read something a long time ago that said it was identified in Malamutes, too, but I couldn't tell you where now. Sorry.


If you read the whole article this is what it states about CRD2, there may be similar diseases but it is not the same as CRD2.

What breeds of dog carry crd2? To date, the mutation causing crd2 has only been observed in one breed of dog, the APBT. Researchers were somewhat surprised to learn that this mutation was not the cause of a very similar disease that occurs in a closely related breed, the American Staffordshire Terrier (Am.Staff.). The Am.Staff.'s disease has been termed Cone Rod Dystrophy 1 (crd1) and is currently being molecularly characterized. Because Pit Bulls and Am. Staffs share many common ancestors and interbreeding among these and other bull-type dogs is quite common, OptiGen will accept samples from any of the "bull" breeds for crd2 testing. It should be emphasized, however, that there is currently no evidence to suggest that crd2 is present in any breed besides the APBT. Owners of pedigreed dogs that have been diagnosed by a veterinary ophthalmologist as having retinal degenerations (e.g. PRA or CRD) are encouraged to contact OptiGen to inquire about our Free DNA testing/Research program (OptiGen - Research).
--


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## bahamutt99 (May 14, 2008)

That is not the article I read. As I said, this was some time ago.


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## performanceknls (Apr 4, 2009)

This is the new up to date info on CRD2, it does not effect any other breed at this time. the amstaffs have a similar mutation but again it is not the same disease and is being researched for that DNA marker as well. Malamutes may have a similar disease but the question being asked was when will this test be available for other breeds. As of right now the only breed it effects is the APBT as of 2010.

Let try and not confuse this with other eye issues with other breeds.


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## American_Pit13 (Apr 23, 2007)

Has their been research into other breeds having this? I am wondering if it is so hard to spot if you don't know what your looking for, if it has been over looked and never checked for or if it actually just does not exist in other breeds.

For example any breeds that where used in the creation of the APBT.


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## performanceknls (Apr 4, 2009)

Thats a good question but many other breeds have known eye issues that are being research and so far it is not the same mutation as the APBT but that could change.
They are saying that if you have a pitterstaff or bully with APBT in them to get the test because it still could be identified because of the APBT DNA. they are currently looking at pitterstaff and Amstaff blood in the research and it is still on going. I am no too sure about bully because of all the recent out-crossing to other breeds.


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