International Conference on Feline and Canine Genetics
by Gordon Theilen, DVM
University of California - Davis
August 3, 2006
I thought you would be interested in knowing about the International Conference on cat and dog genetics being held at UCD and sponsored by the Veterinary Genetics Laboratory. This is where Brittany DNA Studies are being conducted and establishment of the only Brittany DNA Bank in the world. These studies were made possible by initiation of the Marvin Nelson Jr. Memorial Fund established in 2004 and supported by many Brittany persons and the ABC. I am representing the American Brittany Club at this meeting.
The conference was held last year in Europe and is the fourth annual meeting. Today the highlights were:
The establishment of the domestic cat genome, a huge break through for cat breeders and owners. The dog genome was described in 2005 following that of the human in 2004. These genome projects have come at a huge cost and outlines that this type of research does not come cheaply. The cost of the dog genome project was $46 million, but now the door is open to start to better know about gene markers for dog health problems and understand wanted and unwanted traits.
An interesting paper was given on feline spinal muscular dystrophy which occurs in about 1 of every 1,000 cat births showing up at birth or by 3 months of age. A location of a novel gene seems to be implicated. Dogs too have SMD and this research will certainly help us understand this malady in the puppies. Two interesting papers were given on new technology of finding gene markers in the dog. One by our own Dr. Mark Neff ,who gave a seminar on Dog genetics last year at the National ABC membership meeting in Booneville. He indicated that the lab at UCD is now using 3000 gene markers in comparison 12 markers are used by AKC to determine identification and parentage. This technique should speed ability to find gene loci in disease of the canine as well as identify traits. There was a paper on genetics of sweet taste in carnivores and another on the olfactory receptor genes in the dog.
A presentation of the location of Major Histocompatability complex class II genes in immune mediated diseases including diabetes, polyarthritis, hypothyroidism and immune mediated hemolytic anemia and susceptibility to cancer with some dog breed variations in occurrence was given. We are seeing a lot of Brittanys with these diseases and of interest is in some aggression associated with hypothyroidism.
There were some very good posters with one indicating that the Brittany is more closely related to the English Setter and the English Pointer more closely related to the German Short Hair Pointer. Another excellent poster was Genetic testing and counseling that stressed breeding known carriers and those known to be free of carrying an unwanted genotype. This poster was in essence the art of breeding combined with genetic knowledge leading to a good breeding program and strengthening the gene pool rather than eliminating strong traits at the expense by elimination of an unwanted genotype.
My assessment is the spin off from basic genetic research to implementation for breeders will take time and the main word is patience until gene markers are known and used in our breeding programs. The Portuguese Water Dog is receiving a lot attention because the breed is small in number, most dogs in the USA trace back to a very small gene pool and the breeders and owners are in total commitment to DNA research. Using this breed as an example, breeders almost eliminated the strength of the gene pool because 16% of the population were known to have a gene marker for GMI-gangliosidosis ( a progressive lethal paralysis in young dogs) and immediately these carrier dogs, identified by gene markers were being neutered or put down so they could not pass on the unwanted gene. However, in so doing they were also eliminating many dogs that possessed wanted traits, and were weakening the gene pool. This is a lesson to Brittany Breeders that when we find gene markers, we want to be sure we know what we are doing when starting a program to eliminate carrier dogs. Obviously the affected dogs must be eliminated from the gene pool, but the carrier dogs must or might be carefully maintained in order to not destroy other wanted and needed traits to strengthen the gene pool. Such a program dictates total openness in breeding known carrier dogs.
Hope this has been of help by appraising you of what is going on dog and cat genetic research with researchers in attendance from all over the world. I will report back on tomorrow's sessions.
Today's sessions given at the International Conference on cat and dog genetics was full of information about seeking and in some investigations finding new mutations and gene changes leading to disease and identification of some genes for elimination of carrier genes. The dog genome is made up of 3 billion biochemical letters ( amino acids that make up the genome GTAC) and the difference of just one letter being substituted for another in sequence in a gene can change a dog from normal to a carrier or affected with a disease.
Canine Hip dysplasia ( CHD) or also called canine osteoarthritis begins in embryonic life and is a linear progression to signs of clinical and radiographic disease. Hip laxity which may lead to CHD has been genetically identified in some breeds, not the Brittany, and is more frequent in the left than the right hip.
Think of the dog and its genetic make as relationship to disease to be interaction between nutrition, stress, sex, and age. The onset of adult genetic diseases have in some cases been identified such as hypothyroidism in Keeshunds. A study by Dr. Neils Pedersen, director of the CCAH and the UCD Genetics Lab demonstrated that dogs allowed to mate wild such as the Bali Dog, Australian Dingo and New Guinea Dog have an extremely diverse immune system in relationship to major histocompatability Antigens whereas many well known domesticated dogs have a very narrow range of genes associated with histocompatability that results in a wide range of diseases known as hypothyroidism, and many other autoimmune mediated diseases.
The take home lessen is keeping the immune system diverse by proper breeding and carefully outcrossing to widen the gene pool. Careless line breeding and inbreeding when looking for just a few genetic factors can lead to a narrow histocompatability antigens and make such dogs at high risk for autoimmune mediated diseases.
The popular breeding of Brittanys for color when we have so many colors to choose from may narrow our gene pool. This needs research investigation to determine if Brittany color is associated with narrowing our gene pool.
Hope todays report from the International Conference has given breeders some food for thought.
Canine DNA research is exploding with unbelievable new findings. The key to advancing knowledge was description of the dog genome in 2005.
Such research has investigated the skeletal make up, size and length of bones and the genes responsible and variance between male and female for such anatomic make up. Many breeds of dogs are genotypic carriers for biggness when a medium sized or small dog has phenotypic standard size and for smallness if a larger or medium sized breed has phenotypic standard size.This may not be new to breeders, but what is new there are now gene markers for such anatomic structures. Not yet commerically available. This knowledge will become useful for Brittany breeders that have had problems with oversized and undersized dogs as well as fine boned versus heavy boned and length of jaws and noses.
Genetics of hair coat and color was discussed with highlight discovery of the merle gene ( autosomal incomplete dominant trait) and its association with blindness, deafness, ocular problems, sterility, cleft palate and other anatomic aberrations. Apparently the blanching of color, like dark orange to a lighter colored orange as some of you know is seen in the Brittany is under a yet to be found different color gene. Color genetics has become important such as that found in dogs with the merle gene and the Brittany with many different colors within the same breed could make future contributions in dog genetics yet to be discovered.
It was stressed that melanin pigment is necessary for dogs as well as humans in embryonic stages to develop proper hearing. We are starting to see some hearing problems in Brittanys associated with whiteness and this type of deafness may occur in one ear only and not be really obvious like the total deaf dog, but still impact upon such a dog's training and ability to perform. Be aware of this in your breeding programs. There are other types of inherited deafness unrelated to connection with whiteness.
The inheritance of blindness was discussed and seems to be one form or other of cataracts, even what we have called in the past progressive retinal atrophy. Yes, it is diagnosed as PRA, but associated with a cataract gene. Some types of blindness are seen shortly after birth while other types may go though progressive stages of loss of sight starting with night blindness and progressing to total blindness in middle or advanced age. Progressive type of blindness has been reported in the Brittany. I am not sure about the inherited juvenile form, if this type has been reported please contact me. Pups are born with severe cataracts and are blind at birth or become totally blind at a very early age.
Genetic engineering is being used in treating certain canine diseases. To date, the conditions treated involve paralytic diseases resulting after therapy in good improvement. These dogs and the inherited conditions are serving as models to better develop therapy for similar or identical diseases in the human.
For almost all genetic diseases including cancer, the dog has become the premiere animal model to study the same or similar genetic problems of human beings. Keep in mind that genetic problems in your dog(s) can be of value for other dogs, but humans as well.
It must be stressed, for all studies it takes hundreds to thousands of DNA samples to understand the genetic problem being investigated. Brittany DNA Studies conducted at UCD will accept all DNA samples submitted from normal and unhealthy dogs, free of charge. This request must be taken very seriously by all Brittany owners and breeders if we are to bring the Brittany into the loop of productive DNA research. We have now approximately 300 Brittany DNA samples in the DNA Bank. We need many thousand samples. This request will be made over and over and there are many Brittany people out there helping collect DNA samples. If any on the list are contacted by one of more volunteers for collection of DNA, please submit your dog(s) DNA for this unique DNA Bank. Some friends in Canada are also helping in this effort. If there are persons on the list interested in becoming a volunteer to collect DNA, please contact me and we will make arrangements to get you involved in this important step in Brittany DNA Studies. It is repeated, "the cost of placing DNA samples in the UCD Brittany DNA Bank is free to the Brittany owners/breeders. Please do not confuse Brittany DNA identification for AKC certification with the Brittany DNA Bank and genetic studies at UCD. The studies at UCD establishes identity, but the commercial lab doing AKC and AM. Fld. DNA, also at Davis, Ca. but not affiliated with UCD, is the only lab at present that AKC identification certificates are allowed to award identification certificates.
It is obvious, the future will bring to breeders the spin off from the Brittany DNA bank and subsequent research to better their breeding program. It takes you all to make the program a success.
Hope these communications ( only a tip of all information given the last three days at the International Conference) have been of value and give all a sense for the importance of DNA research beyond what AKC and Am. Field require for DNA identification and establishment of parentage. Finally, DNA research is very costly, many of the findings presented in the last few days have been liberally supported by many sources especially when they are models for study of human disease at costs that are in the millions of dollars per one investigation per year which may involve researchers located at many research institutions. Ralston Purina is involved in some of these projects and funded this International Meeting. They help in other ways by supporting some of our events in ABC.
Please identify problems in the new born, pup, young adult or in advanced age and list them on the DNA samples when submitted. Save puppy tails when docked, this starts immediately a DNA study on a dog family. Speaking of tails, the Brittany is the only pointing breed that may be whelped with a short tail. We are very interested in DNA from all natural bobbed tailed Brittanys and their relatives. Do you realize that humans have not lost the gene for tails seen in other primates. Short tailed genes are of considerable interest. We have important health problems, anatomic structures, and traits in the Brittany of which some will be eventually investigated, but to do so we need DNA samples. Let's not allow other breed clubs to surpass us in dedication for DNA research.
As you can read, this conference turned me on more than the AKC Health Foundation Symposium for dog clubs last October where posters were given by most of the 201 breed clubs represented and some of you may not have learned that the American Brittany Club won the first place prize for posters presented at that conference. We were well represented there, and we must continue to be on the forefront and cutting edge of DNA research to benefit our breed. We can only succeed with your help.
Gordon Theilen DVM
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