# DNA Testing for breed of horse



## hallarider (19 March 2008)

Hi Everyone

I have had my mare for 11 years now and bought her from a dealers yard back then who said she was cob x tb.  I believe she has arab in there somewhere.  

I was wondering if there was anywhere they can test the horses dna to see what breed they actually are???

many thanks


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## KarynK (19 March 2008)

Yes there is a way of testing for "breed" genes but it is in it's infancy and would be very expensive, they can do it via mitochondrial DNA which is not involved in sexual reproduction so  does not change very much through the generations and thats why it is excellent for tracing racial origins back thousands of years.


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## Loika (20 March 2008)

Mitocondiral DNA will only give the maternal line.

There isan't a massive amount of funding for horse genome so it is unlikely that any results would be that informative.  Also with breeds being a fairly recent invention the amount of deviation between horses will not be definative to indicate specific breeds.  So often there has been cross breeding to "refine" a breed and weatherbys has only be a closed studbook for just over 200years which is not sufficient time to build up significant variation.  Even Human tests can only give a vague percentage of chance.  

If you want to find out more, what about a horse finder type website??  I reunited my old cob with his previous owner, even though I hadn't seen him in 10years.  It was great to talk to her about him!!


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## KarynK (20 March 2008)

On the contrary Its already been done, some time ago in fact, using  Mitrocondrial DNA which has mapped origins of American breeds through female families i.e. breed genes found within Mitochondrial DNA which has a variation rate of 0.0115  mutations at any position in HV1/HV2 per generation.

http://www.pnas.org/cgi/reprint/99/16/10905.pdf
and http://news.bbc.co.uk/1/hi/sci/tech/2129182.stm

It should also be noted that it is possible to inherit Mitochondrial DNA from a male parent in mamals, though this is very rare.  

The paternal line identifier Y STR (Short Tandem Repeat) can also be used to establish inheritance in male lines by studying inheritance from father to son of so called "junk DNA" found on the Y Chromosome.


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## Loika (21 March 2008)

The paper you have quoted is interested in original domestication (population genetics) of horses which the mtDNA is an ideal target.  However this type of data will not provide the information that hallarider wanted, variation between breeds is more likely to be identified in the genome especially with closed studbooks like arabs and TB's.  TB horses are parentage tested against their parents to confirm the ancestry in the same way a a paternity test for humans.  Specific genes are needed to determine between "races", there is no current econmic need for this information so the research is unlikely to occur except in acedemia.  If I ever go back, it will be a subject to look into.

To determine between breeds more than the mtDNA and Y chromosome data will be needed, other genes contained in the genome, for example those potentially associated with the enlarged heart and lungs of the Thoroughbred and other key features could be targetted.  Dished face, number of ribs, bone density, feathers(distribution), size etc could all be targets.
Domestication is predicted to have occured several thousand years ago and the haplotypes appear to brake down geographically so still not refined enough to determine between breeds in a potentially mixed mare.

I was trying to explain things simply, not everyone has the same level of training as you KayrnK and I.  If you want to debate further please pm me, but not about repeats because I have had enough of those!!


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