Page 681 - WSAVA2017
P. 681

WSVA7-0500
WSAVA HEREDITARY DISEASES
LESSONS FROM COMPREHENSIVE GENETIC SCREENING OF COMPANION ANIMALS
J. Donner1
1Genoscoper Laboratories, -, Helsinki, Finland
LESSONS FROM COMPREHENSIVE GENETIC SCREENING OF COMPANION ANIMALS
Jonas Donner, PhD
Genoscoper Laboratories, P.O. Box 1040, FI-00290, Helsinki, Finland
jonas.donner@genoscoper.com
The ease and affordability of access to genomic information, and consequently the number of genetic tests available to breeders and veterinarians, has changed radically over the past 10 years. More than
200 canine and 60 feline genetic variants underlying Mendelian disorders or traits have been described to date [1]. When limiting the consideration only to known breed-relevant tests, we are still faced with availability
of 5-10 DNA-based disease tests for many breeds. At the same time, public information on the population prevalence of the disease variants targeted by the tests, their relative importance for breed health, and distribution across breeds, is typically incomplete.
In addition to disease testing, genetic information is readily available for companion animals on various conformational and morphological traits, breed ancestry/ background, and through DNA-profiling for parentage verification. In general, genetic testing is currently pursued for the most part on the initiative of breeders complying with breed club recommendations, or driven by dog owners’ curiosity about their dogs genetic background. However, genetic diagnostics has the potential to develop into an important supportive part of predictive, preventive, and personalized pet care given adoption of available tools in veterinary medicine.
A recent trend among DNA testing laboratories
offering services for companion animals has been the restructuring of services from offering one-by-one single gene tests to providing multiple disorder or trait tests
at once as “combination packages”, “panel tests”,
or a buffet where the orderer picks the desired gene tests. Although this transformation of genetic testing undoubtedly has benefits for multiple parties in terms
of synergistic sampling, sample logistics, analysis and reporting, it understandably warrants an informed and responsible approach. The scientific foundation and power of comprehensive screening to advance our knowledge on the distribution of disease variants across
breeds has been established, with mutation findings in unexpected breeds typically explained by either shared breed ancestry or recent cross-breeding [2]. However, high service provider standards of following up on unexpected discoveries through both additional genetic experiments and clinicopathological follow up studies are a necessity.
In more detail, a number of valuable lessons have
been learned from our genetic screening studies encompassing more than 100,000 canines representing the general population of both mixed breed dogs and purebreds [3].
LESSON 1: Risk variants for Mendelian disorders are prevalent in the general dog population, but a subset of around 30 disorders account for the majority of disease allele observations. When screening for 152 known Mendelian disease risk variants in 100,000 dogs, we noted that 40.5% of all dogs (41.8% of mixed breed dogs vs. 32.0% of purebred dogs) carried at least one of the tested disease variants. The maximum number of disease variants carried by any individual dog was five.
LESSON 2: Mixed breed and purebred dogs share
the same common Mendelian disease variants. The majority of the tested disease variants were found in
both populations of dogs studied, and the list of top
12 most common disorders by allele frequency was virtually identical in both groups. Some disorders are likely to have been eradicated from the natural population through selective breeding.
LESSON 3: Mixed breed dogs are more likely to carry a genetic disorder, while purebreds are more likely to be genetically affected with one. For the first time, we provide direct genotyping-based evidence for hybrid vigor in mixed breed dogs.
LESSON 4: Disease allele prevalence information best serves the community when accessible and updated. We have created an online canine inherited disorder prevalence database, MyBreedData, (mybreeddata. com; [4]) featuring the possibility to search for disease genotype frequencies by breed or by disease. This resource is freely available as a tool to advance breed health research and veterinary medicine.
LESSON 5: Mixed breed dogs are likely to display signs of many of the same disorders affecting purebreds. Clinical follow up studies are always needed to confirm mutation effects on other genetic backgrounds. Such additional investigations should ultimately guide how and if a genetic variant should be considered in the overall breeding program. In some instances, comprehensive genotyping across breeds has revealed that the conclusions made in an original study may have been
An Urban Experience
  681
                   



































































   679   680   681   682   683