Recently we received a question from a Harmonization of Genetic Testing (HGTD) user, who had wanted to use an "Ancestry" genetic test to determine a puppy's likely sire. It is not uncommon, when trying to determine the right test for your purposes, to mistake "Ancestry" tests for parentage, or genetic identification tests. The information below talks about what ancestry, or breed mix genetic tests are, how they can be used, and some of the limitations.
What is an Ancestry/Breed Mix Genetic Test for dogs?
Ancestry/breed mix tests are a way to estimate what breeds compose your mixed-breed dog, or to help determine what breed(s) your dog of unknown origins might be. You can find more information about the different kinds of genetic tests available, here. It is not uncommon for people who use an ancestry/breed mix test to have some surprising results. Understanding how these tests generally work might make it easier to understand your results.
At its most basic, an ancestry/breed mix test compares specific sections of your dog’s DNA, known as markers, to a reference database of hundreds of dog breeds or types. A genetic marker is a DNA sequence with a known physical location on a chromosome. Genetic markers can help link an inherited disease or trait with the responsible gene. This data estimates the likely breed(s) that compose your dog, to a few generations back (e.g. grandparents). You can find genetic test providers offering these kinds of tests by searching for "Breed/Type/Variety test" on HGTD.
How precise these tests are is dependent on a number of factors, including:
- The size and scope of the reference library
- The number of specific areas (referred to as genetic markers) of DNA the test “looks” for in your dog
- How well understood the markers are, and how well they correlate with genetic markers associated with breed-specific traits
The size of the reference library, in terms of gene coverage and breed/types included is important to improve precision. Arguably even more important is having genetically well-defined breed samples, and knowledge of breed population-specific challenges such as breed population variations or genetic diversity. More markers doesn’t automatically mean “better” if the markers don’t associate well with specific breeds – though you also need a large enough number to differentiate between breeds/types.
When you look at different test providers information online, you can usually find information on how many breeds are included in their reference panel, how they determined which dogs to reference, what kinds of genetic markers they are using for comparisons, etc. They should also be able to tell you how many “generations” they are including in your dog’s results and answer any questions when your results aren’t what you might be expecting.
How are Ancestry/Breed mix tests helpful?
If you have a dog of unknown origin, these tests can help give you some idea of the dog’s traits - such as size, temperament, and even potential health risks. Test packages vary, but in addition to breed estimation, often include some specific genetic tests for traits (like coat colour) and sometimes disease risks.
If you have a mixed or crossbreed dog you are considering using for breeding, the testing packages with breed or type-specific disease risk results can help in choosing suitable mates to reduce the risks of inherited diseases in subsequent generations of dogs.
What Ancestry/Breed tests do not do:
- It is not a way to confirm a pedigree breed, or refute pedigree papers.
- It is not for determining parentage.
- It is not necessarily for permanent ID*.
- It does not determine “health” nor determine all inherited disease risks. (e.g. there are many inherited diseases that cannot currently be genetically tested for).
So, what is a Parentage test?
A parentage test works by collecting DNA samples from the dam, sire, and offspring to determine each individual dog's unique genetic profile, based on a special group of genetic markers. This special group of markers might be called a "parentage panel" or "genetic profile panel" or by the technical type of reference panel used. There are 2 main reference panels for this purpose: ISAG (International Society for Animal Genetics) and the AKC (American Kennel Club) Panel. Each dog's unique genetic profile of markers is compared, and, much like in human parentage testing, if enough markers are in common, you can confirm parentage. Likewise, you can confidently exclude possible parents. In very rare cases, if the dogs are highly inbred, or the disputed parents are very closely related and inbred, it can be more challenging to absolutely determine parentage. You should expect your genetic test provider to have very specific protocols for sample collection for parentage.
Benefits of parentage profiling:
- Improves accuracy of pedigree data
- Confirms accuracy of hereditarily clear by decent genetic test results
Limitations of parentage profiling:
- Parentage can only be robustly confirmed when you have data from the dam, sire, and offspring
- You cannot normally “back-determine” parentage from other relatives data – e.g. you can’t use combinations of grandparents, siblings, half-siblings, etc.
- For highly related or inbred matings, there can be challenges in determining parentage
- You cannot determine parentage using incompatible marker panels (e.g. ISAG + AKC)
A breed ancestry or breed mix test estimates the likely breed(s) that make up an individual dog.
A parentage test identifies specific, related individuals: parents and offspring.
*different product packages may include options for including permanent ID
Cover photo: Eddie Galaxy via Pexels.