The Optigen prcd-PRA test

The OptiGen prcd-PRA test is a DNA-based test that helps you avoid one form of Progressive Retinal Atrophy (PRA). PRA refers to a group of diseases that cause the retina of the eye to degenerate slowly over time. The result is declining vision and eventual blindness. “prcd” stands for “progressive rod-cone degeneration” which is the type of PRA known in several breeds. AFTER reading the information on this page, you can link to information specifically about the breed in which you are interested.

PRA disease

The genetic disorder, prcd-PRA , causes cells in the retina at the back of the eye to degenerate and die, even though the cells seem to develop normally early in life. The “rod” cells operate in low light levels and are the first to lose normal function. Night blindness results. Then the “cone” cells gradually lose their normal function in full light situations. Most affected dogs will eventually be blind. Typically, the clinical disease is recognized first in early adolescence or early adulthood. Since age at onset of disease varies among breeds, you should read specific information for your dog. Diagnosis of retinal disease can be difficult. Conditions that seem to be prcd-PRA might instead be another disease and might not be inherited. OptiGen’s genetic test assists in making the diagnosis. It’s important to remember that not all retinal disease is PRA and not all PRA is the prcd form of PRA. Annual eye exams by a veterinary ophthalmologist will build a history of eye health that will help to diagnose disease.

Unfortunately, at this time there is no treatment or cure for PRA. If your dog is affected, you may find it helpful to read about other owners’ experiences living with blind dogs. (suggested links:www.eyevet.org and www.blinddogs.com)

Inheritance

Prcd-PRA is inherited as a recessive trait. This means a disease gene must be inherited from each parent in order to cause disease in an offspring. Parents were either “carrier” or affected. A carrier has disease gene and one normal gene, and is termed “heterozygous” for the disease. A normal dog has no disease gene and is termed “homozygous normal” – both copies of the gene are the same. And a dog with two disease genes is termed “homozygous affected” – both copies of the gene are abnormal.

It’s been proven that all breeds being tested for prcd-PRA have the same disease caused by the same mutated gene. This is so, even though the disease might develop at different ages or with differing severity from one breed to another.

Although prcd-PRA is inherited, it can be avoided in future generations by testing dogs before breeding. Identification of dogs that do not carry disease genes is the key. These "clear" dogs can be bred to any mate - even to a prcd-affected dog which may be a desirable breeding prospect for other reasons. The chance of producing affected pups from such breedings depends on the certainty of test results. Again, you’ll find the specific information on certainty of test results for your dog by linking to breed specific information.

The genetic test

The OptiGen prcd test is done on a small sample of blood from the dog. Currently, the test analyzes DNA markers rather than a mutation. (Active research is underway to develop the preferred mutation test.) This means that dogs are identified by a "fingerprint" of markers on chromosome 9 near the prcd gene, rather than by directly detecting the prcd mutation itself. The result of the test is a genotype or pattern - a fingerprint - that allows separation of dogs into three groups: Patterns A, B or C, and for some breeds: Patterns A1, B1 or C1.

The degree of certainty for a test result depends on the specific test developed for a breed. You should read about frequencies of false positive and false negative results at the link to your breed. The possibilities for less than 100% certainty, whether normal, carrier or affected, can be due to frequencies of markers in a specific breed, or due to the estimated rate of recombination of markers or new mutations. While these considerations become fairly technical, we can provide straight forward estimates of “certainty” for each breed. With full information, the reliability of the prcd test in evaluating a particular dog lets you control prcd-PRA in future generations.

Breeding strategies
 

This table highlights all the desirable breedings that include at least one parent with Pattern A or A1. All other breedings are at risk of producing pups of Pattern C or C1 with a high probability of developing prcd. However, all dogs can be bred safely. It isn't necessary - or even desirable - to remove dogs from the breeding population. But when choosing pups to retain as potential breeding stock, it is important to select for dogs with Pattern A or A1 and select against dogs with Pattern C or C1.

Benefits & limits to all genetic testing

The benefits of genetic disease testing are clear. With informed breeding practices, breeders immediately can avoid producing affected pups, yet use any dog in their program regardless of genetic disease status. And since genetic testing can be done at any age, each dog’s genetic status can be known before clinical disease signs are recognized. Over several generations of selection away from the disease gene, breeders can even eliminate a disease gene completely from their line.

BUT, there are basic limits for any and all DNA genetic tests. Whether a test is mutation-based or marker-based, it identifies only the specific mutation being tested or the association between a specific marker set and the disease. For example, a mutation test detects one specific mutation in one specific gene. If there are several different mutations or several different genes that can cause the same condition, one must discover and then test for each mutation and each gene. Likewise, a marker test uses one marker or set of markers to define a specific condition. If the condition is associated with several different marker combinations, one must discover and then test for each marker combination. It can be difficult or even impossible to know how many mutations or how many marker sets exist in all the members of a specific breed. As more and more dogs are tested, previously unknown variations may come to light.

In the case of PRA, also keep in mind that not all retinal disease is PRA and not all PRA is the form currently detectable in your breed. Accurate diagnosis is essential. A dog can test as normal or carrier, yet be affected a different type of PRA. Although more than one type of retinal degeneration probably occurs in every breed, by far the most common type of PRA for your breed is the type currently being tested by OptiGen.

NOTE: IMPROVED ECS TEST IN USE AS OF JANUARY 15, 2003
 

We are very pleased to announce that an improved marker test for English Cocker Spaniels is now ready. Much credit for this advance goes to the ECS owners who participated in this research effort by supplying new CERF exams for their dogs. While this new test is significantly improved over the original test, it is not yet the direct mutation test we all are working toward.

As you know, the original prcd-PRA test for ECSs can give false allele (false positive) results for the Pattern B and Pattern C categories. Ongoing research by Drs. Greg Acland and Gus Aguirre and their research team at the Baker Institute of Cornell University focuses on discovering the actual gene and mutation causing prcd-PRA. As part of their ongoing research, they also evaluate new DNA markers for prcd-PRA. Some of these markers have potential use for improving the prcd-PRA marker tests. Earlier, such effort led to significant improvement of the prcd-PRA tests for Portuguese Water Dogs and Chesapeake Bay Retrievers.

Success With A New ECS Marker
 

One marker in particular gives very reliable new information about prcd-PRA in ECSs. This marker was evaluated first at the Baker Institute on their set of research samples from ECS, including known PRA-affecteds. When it looked solidly promising, OptiGen tested the new marker further. Acceptance of the new marker would be based on test results from 166 Pattern C dogs correlated with their clinical status of non-affected or affected, as reported by CERF exams.

24 known PRA-affected ECSs were studied with the improved marker test and all were Pattern C1. (A1, B1 and C1 designate results from the improved test.) There are no ECSs known to OptiGen as PRA-affected that do not test as Pattern C1.

65 additional Pattern C dogs stay in the high-risk group of Pattern C1 even with the improved test. Some of these C1 dogs are under 4 years old, which usually is too young to detect development of PRA. However, some of these C1 dogs are between 4 and 12 years old and still pass CERF. This could be due to two explanations. 1) Some false alleles remain with the improved test, still to be resolved with further research. Non-affected C1 dogs should be CERFed annually, as usual, and report copies shared with OptiGen. 2) The age range for ECS to show signs of PRA is much later than other breeds. ECS as old as 12 years are diagnosed with PRA. C1 dogs currently passing CERF may not do so in the future.

The remaining 77 ECSs that were reported previously as Pattern C now test either Pattern B1 or Pattern A1. None of these had a diagnosis of PRA on CERF exam.

Likewise, over sixty dogs that originally tested Pattern B now test Pattern A1 with the improved marker test.

Adjusted Pattern Distributions
 

Use of the improved test on all of the ECS samples tested by OptiGen so far shows that the number of Pattern A1’s increased by 1/3, the number of Pattern B1’s stayed about the same and the number of C1’s decreased by 1/2. These trends were expected based on the experience of breeders, and now the improved test reflects this expectation.

Results for OptiGen tested ECS samples show the following Pattern distribution with the original and the improved tests.

PATTERN RESULTS
	A	B	C
Original Marker Test	29%	45%	26%
	A1	B1	C1
Improved Marker Test	40%	46%	14%

Additional Points
 

• The OptiGen prcd test can be done reliably at any age – even in young pups, and the result will be the same at any age, and will be the same whenever it is repeated. In the future when an improved test is offered that further increases levels of certainty, a repeat with the improved test might be recommended.

• Since most breeds are affected with other inherited eye diseases, we recommend that yearly eye examinations by a board certified veterinary ophthalmologist be continued, for example, through the CERF program in the U.S. or similar program elsewhere. However, a normal exam in a young dog cannot rule out PRA at a later age. To establish PRA affected status by ERG, it is necessary that a full diagnostic protocol be done with dogs under anesthesia or heavy sedation, and that the rod and cone contributions of the ERG be separately evaluated.

• Tallies of test results are updated and provided quarterly to national breed clubs, at their request.

NEW MUTATION TEST IS NOW AVAILABLE !!!

June 1, 2005
Press Release
 

Ithaca, NY: OptiGen, LLC, proudly announces identification of the gene causing canine prcd-PRA (progressive rod-cone degeneration form of Progressive Retinal Atrophy). The cause of this inherited blinding disease, occurring in at least a dozen purebreeds, is one specific mutation in the coding sequence of the gene. OptiGen now offers a direct gene mutation test (mutation test) to detect the prcd-PRA status of any dog among affected breeds.

This success results from years of extensive investigation by Dr. Gus Aguirre and Dr. Greg Acland and their research staff at Cornell University. Essential cooperation from multiple breed clubs and more recent participation by OptiGen completed the team. The research data defining this mutation are being prepared for publication in a scientific journal. Commenting on future work, Dr. Aguirre says: “Going forward, the biological action of the prcd gene in the retina will be studied, with goals of understanding the basis of this disease and searching for treatments or even, eventually, cures.”

The new OptiGen prcd mutation test accurately detects the presence or absence of the mutant prcd disease gene copy. It replaces earlier OptiGen DNA-marker-based tests (marker tests) that detected changes in coding sequences of genes located near to and inherited with (linked to) the prcd gene. OptiGen henceforth defines result status based on the mutation test as “Normal/Clear” or “Carrier” or “Affected.” Designation of Patterns A(A1), B(B1), and C(C1) for previous marker tests are retired.

While the basic research of Aguirre and Acland spans decades, OptiGen’s prcd-PRA test evolved over the last 7 years, with the first marker test offered to Portuguese Water Dogs in 1998. Initially it detected false positive alleles. Subsequently, improved versions of the marker test analyzed coding sequence changes in more tightly linked genes and greatly reduced the frequency of false alleles. This improved marker test accuracy and gave an excellent estimate of prcd-PRA frequency within affected breeds.

A crucial set of information for proof of the prcd mutation was generated by OptiGen, according to Dr. Jeanette Felix, President. Between March 1, 2004 and May 31, 2005, OptiGen had added the potential mutation test to the standard marker test for all new samples from prcd-affected breeds in order to validate the identity of the mutation in large populations. Analysis now shows that the results are consistent between the marker test and the potential mutation test.

The prcd mutation test further improved accuracy over the marker test for Labrador Retrievers and Miniature and Toy Poodles. Only these groups will receive updated test reports by mail during June. For all other breeds, there was no difference in the outcome between marker and mutation tests. Given this match, OptiGen will not retest other breeds originally tested before March 1, 2004. All test reports that gave Pattern status can be interpreted as: Pattern (A)A1 = Normal/Clear; Pattern (B)B1 = Carrier; Pattern (C)C1 = Affected.

Statistics based on the new mutation test show that the frequency of prcd-PRA varies substantially among breeds, ranging between 4% to 20% affecteds and 20% to 50% carriers. Dr. Acland emphasizes: “Genetic testing used in informed breeding programs clearly is essential for preventing new cases of vision loss. I expect more genetic tests will be developed as canine genome research accelerates. Breeders with experience using the prcd-PRA test will be eager to make use of all new genetic information.”

The prcd-PRA mutation test can be obtained following the same procedures as before - see www.optigen.com. As of June 1, 2005, the fee for the prcd-PRA test is reduced 25%, down to $195. Opportunities for discounts for litters, through online ordering and 20/20 Clinics continue.

The Morris Animal Foundation/The Seeing Eye, Inc. is a major sponsor of research by Drs. Acland and Aguirre. Grants from the NEI/NIH, the Foundation Fighting Blindness and The Van Sloan Fund and contributions from many breed clubs, organizations and individuals are gratefully acknowledged. Many club health committees and breeders gave welcome encouragement as well as invaluable samples and information on their breed lines.

OptiGen, LLC, is a private company established to provide canine genetic tests to breeders and owners of purebred dogs, their veterinarians and other veterinary specialists. OptiGen holds an exclusive international license to the Cornell University technology for prcd-PRA mutation testing, and exclusive and non-exclusive licenses to multiple other technologies developed at Cornell and elsewhere.

Added notes:

Price: The reduced price for the prcd-PRA mutation test is effective June 1, 2005. For samples received at OptiGen June 1st and after, credit cards will be charged the correct price, even if your online order indicated a higher price. If you sent a check and overpaid, you will receive a refund by mail. The 20/20 Clinic price now is $US156 or $US146.25 if ordered online. The Litter Rate price is $US135 per pup.

Re-Testing with the prcd-PRA mutation test: You do NOT need to request or order a re-test if your dog was tested already. Only a sub-group of Labrador Retrievers and a subgroup of Poodles needed a re-test. These have already been done by OptiGen at no charge and re-test reports are in the mail. No other dogs require a re-test.

How to proceed ?

The prcd-PRA test is done on a small sample of blood obtained by your veterinarian. This allows the lowest risk of contamination of the sample and added assurance of a match of the sample with the identified dog.

Ship sample

Veterinary Appointment

Blood can be collected by your veterinarian or a licensed veterinary technician and must be processed according to the instructions below. OptiGen does not supply a sampling kit, since your veterinarian will have the necessary supplies. Make an appointment to have a blood sample drawn early in the week to avoid shipping over the weekend. Inform the clinic in advance that the blood must be drawn into a small lavender (purple) topped vacutainer tube and that the blood MUST be unclotted.

Test Request Form

Complete the Test Request Form (http://www.optigen.com/opt11_form.taf for online subscription or http://www.optigen.com/opt9_request.html for printable form) with all the required information on the dog to be tested. If more than one dog is being tested at the same time, complete a form for each dog even if they are from the same litter.

Both you and the responsible veterinary staff must sign the form affirming a match of the dog with the PERMANENT ID# AND THE BLOOD SAMPLE.

You may copy the completed form for your records.

UNCLOTTED Blood Sample

Supplies needed at clinic: 18 - 22 gauge hypodermic needles

3 ml or larger syringe. Syringe must be new, in original package, and never re-sterilized.

Lavender (purple) top tube (EDTA anti-coagulant), 3 ml size or larger. If necessary, ACD yellow top tubes are acceptable substitutes.

Sealable (ziplock) plastic bag to hold tube

Two sticky labels marked with owner’s name, dog’s name and date – one affixed to the tube and one to the plastic bag

If blood is being collected from more than one dog, a new needle and syringe must be used for each dog. Each dog’s blood sample must be put in its own labeled tube and labeled plastic bag. Be certain that each label corresponds to the correct sample.
COLLECT 1 – 3 ml of blood from the test dog.
IMMEDIATELY TRANSFER the blood to the anti-coagulant tube.
INVERT THE TUBE several times to prevent clotting. Clotted blood cannot be used. Do NOT send clotted blood. If necessary, a new blood sample should be collected. Do NOT put tape over the cap of the blood tube.

Put the labeled tube into the labeled plastic bag, INSERT 2 FOLDED PAPER TOWELS, and seal securely. Do not insert Test Request Form or check in this bag. Do not freeze the sample at any time. Refrigeration (for no longer than 5 days) is recommended if the sample will not be shipped on the day that it is collected.
 

Send the packet to :

VHL-Dr. van Haeringen Laboratorium b.v.
P.O. Box 408
6700 AK Wageningen
The Netherlands
 

or to :

OptiGen, LLC
Attn: Becky Iddings
Cornell Business & Technology Park
767 Warren Road, Suite 300
Ithaca, NY 14850

In the second case : Note on the packet, in block letters : "PATHOLOGICAL SAMPLES" and print the following text 2 times :

"Regarding USDA Guidelines of Importation - #1102 Feline and Canine Material
I understand that a USDA import permit is not required for this canine material since I can provide the following true statements.
The material in this shipment is canine (dog) blood.
This material does not contain any other animal derived material (ie. from livestock or poultry).
This material was NOT derived from cats and/or dogs which were inoculated with or exposed to any infectious agents of agricultural concern.
I declare that the above information is true and correct to the best of my knowledge.

Signature:

Print Name:

Please contact Becky Iddings at OptiGen, LLC, the recipient, for more information at: phone - (607) 257-0301; fax - (607) 257-0353"

And don't forget to DATE and SIGN that declaration and to put one in the packet and to stick the second one ON the packet.
 

Prices

For the Dollar / Euro conversion, see : http://finance.yahoo.com/m3?u
 

Payment is possible by bank account or credit card (Visa, Mastercard, ...). Online payment is totally secure and the money will be taken off your account the day the test is done in the United-States, not the day you suscribe.

prcd-PRA test cost (per sample) : 195 $.  If online subscription (5 % reduction) : 185.25 $ (per sample).

The cost include a confidential report (sent by fax, email or post mail) and, for the dogs tested genetically normal, a certificate of results. Typical turn-around time for results is 2 to 3 weeks.

Long-term storage of sample = $35 for 10 years
Breeders won't need to supply another sample for future tests as they become available.

Litter Rate for prcd-PRA test = $135 per test (per pup)

For 2 or more pups from the same litter. ALL of the following requirements must be met.

1. Pups must be no more than 12 weeks of age at the time samples are drawn.

2. Pups must have permanent identification by microchip or tattoo.

3. All samples from the litter must be sent at the same time and in the same package.

4. A complete Test Request Form must be submitted for EACH pup. (Use on-line submission and choose "another from the same litter" when you've finished the first submission.)

5. Certificate of normal status for pups will be issued only upon request and for an additional $50 when the owner of record can supply a registered name and number officially linked to either the microchip or tattoo number supplied earlier.

Affected dogs are tested at no charge. Please review the conditions for this before submitting a sample from an affected dog.

Registries: Breed clubs may sponsor genetic disease registries and OptiGen may provide some test information directly to the registry in accordance with the club’s official policies. Please go to your club to learn more about this.

The research leading to this discovery was undertaken by scientists at the James A. Baker Institute of Animal Health at Cornell University's College of Veterinary Medicine in Ithaca, New York, and published in volume 95 of the March, 1998 issue of the Proc. National Academy of Sciences. The patented technology underlying this test is under exclusive license to OptiGen from Cornell Research Foundation, Inc. PCR technology is performed under a license agreement with Roche Molecular Systems, Inc.

What is an Optigen Clinic ?

Several times a year, Optigen organises some clinics, at breeders resquests.  To get 20 to 25 % reduction on the normal price of the tests, 20 dogs at least have to be tested at the same time.

In collaboration with VHL lab ( http://www.vhlgenetics.com ) in the Netherlands, Optigen organises "Satellite Clinic" and fixs a week when all the samples have to be at VHL.  So that VHL knows that the samples are for that or this clinic, Optigen publishs a code to note on the blood samples and on the request test forms.

The clinic formula is, as individual formula, totally confidential.  Nobody knows which dogs are tested, ...  And the results are only given to the dogs owners.  To get informed about the clinics, the best is to regularly visit Optigen website or follow th informations published by the breeds Clubs, the discussions groups, forums, breeders homepage, ....

Thanks to that formula, the test cost can decrease to :

- 146.25 $ for an individual test.

The Optigen test for other breeds