Assessing Genetic Diversity in Kromfohrländer - View to a Cross-Breeding Project

Kromfohrländer, a native German breed, is known to have a very limited gene pool and is thus subject to a cross-European breeding project focusing to expand the pool. Given the vulnerable genetic status of the breed, the Finnish Breed Association for Kromfohrländer initiated a project aiming at measuring the genome-wide diversity of the breed in 2013. Several dogs of Central European origin were also recruited for the study. 

Study population

Through active promotion and enrollment co-ordinated by the breed club above, buccal cell samples from Kromfohrländers (both wire- and smooth-haired) were collected for DNA extraction and analysis. The majority of the samples were collected during January and February 2013. The final study included all Kromfohrländers tested by MyDogDNA service until the end of January, 2014 (108 dogs). Dogs enrolled in Finland represented the majority of the tested population (73 dogs), with the remaining 35 consisting of both German and Austrian dogs. Of special note, the set of Finnish dogs included a cross-breed litter of 9 from a mating of a female Kromfohrländer, and a male medium-sized Poodle (black, brown and white; based on FCI classification).

Results

All test results from individual dogs were automatically stored in the MyDogDNA database to enable real-time monitoring of genetic diversity and the genetic structure of the breed (e.g., possible intra-breed lines).

Genetic diversity

The median heterozygosity of the tested Kromfohrländer population (excluding the cross-breed litter) was 21.2%, considerably lower than the MyDogDNA database median across all breeds (28.8%). This result confirmed the expected vulnerable genetic status of the breed, further emphasizing the need for approaches to increase genetic diversity of the population, such as cross-breeding. The benefits of cross-breeding are instantaneous in terms of genetic diversity: The analyzed Finnish cross-breed litter clearly represents a group of dogs with increased heterozygosity compared to the original Kromfohrländer population.

For further reference, the following table provides an overview to the genetic diversity of Kromfohrländer in comparison to other selected breeds in the MyDogDNA database (situation as of January 2014). The overall current heterozygosity variation in the MyDogDNA database is between 15.3% and 40.1%.

Breed
Dogs tested
Median heterozygosity

Parson Russel Terrier
> 100
34.4%

Finnish Lapphund
> 100
31.8%

Lagotto Romagnolo
> 100
29.3%

Golden Retriever
> 100
27.8%

Kromfohrländer
> 100
21.2%

 

Genetic relationships

The genetic structure of a breed, or genetic similarities and differences between individuals can be visualized with a standard multidimensional scaling analysis. Such visualization can be used to identify possible genetically different breeding lines within the population. It also helps to evaluate which dog could be mated to preserve genetic diversity within the line as well as within the entire breed. Owners are able to map all of their tested dogs in the same image, and by exchanging dog information they will also be able to compare known lineages with each other to see whether they are truly genetically different or not. The plots are automatically updated with each new tested dog that is added to the database.

Overall, understanding of the genetic differences present between dogs in a homogeneous breed will aid in future identification of optimal breeding partners (breeding pairs that will result in offspring that is genetically as diverse as possible). For this purpose, the MyDogDNA service includes a custom-developed tool called MyDogDNA Breeder which is available to users free of charge. This tool uses the measured genetic data to identify breeding partners that are genetically different from the breeder's own dog, and does not carry the same inherited diseases based on the single gene disorder tests that are included in the MyDogDNA panel. In brief, the Breeder tool ranks potential partners according to the expected genetic health and diversity of the offspring. It also displays where the identified partners are located geographically, and offers a direct means of contacting the owner.

Genetic relationships in the Kromfohrländer cross-breeding project

As described above, the Kromfohrländer cross-breeding project has progressed to first generation litters of Kromfohrländer/Poodle mixes. Other breeds besides Poodles were also considered as candidates for the crosses, and may be of future relevance.

The analysis logically places the cross-breed litter genetically between its dam and sire, visualizing the progress made in developing the gene pool of the breed. The participating breed clubs are strongly advised to proceed systematically in their aspirations for increased genetic diversity in upcoming generations. For such a goal, the MyDogDNA Breeder tool will be immensely useful in the future, as it will help to make sure that the gene pool is optimally maintained with minimal loss of the made progress. In particular in a small breed founded by only a few individuals, pedigree information and inbreeding coefficients may be misleading compared to the information provided by actual DNA measurements. This further emphasizes the need for a supportive tool such as MyDogDNA Breeder. If requested by the breed clubs, a custom MyDogDNA Breeder breeding group could be created to allow comparison of Kromfohrländers also to other breeds of potential interest for cross-breeding.

Takaisin