Lets Talk Horse Genetics

[bkreugar]

On the spot I just realized something from going back and reading your post.A tobiano is what I called a "tricolor paint" as it was brown, black and white on the body.

 

[Cara]

LFS only affects a certain Egyptian Arabian bloodline, just as HYPP only affects QH's with Impressive breeding. Chicks_N_Horses was breeding a QH to a QH.

 

[Cara]

This link might help

http://en.wikipedia.org/wiki/Paint_(horse)#Terms_for_color_patterns_defined

 

[sbarab]

If your mare is truly a tobiano and has one purebred arabian parent, she can only be heterozygous for Tobiano (Tt) and a foal of the cross you are wanting has a 50% chance of also being Tobiano. The tobiano gene does not exist in Arabians.

Sometimes arabians like Khartoon Klassic carry the sabino gene. Sabino is very different than tobiano. It is a gene mutation. Check out this site for more information about sabino. http://www.horse-genetics.com/sabino-horses.html

If you are interested in finding out more about equine genetics you might want to check out this site: http://www.hajinc.com/clickit.php?affid=24701 then click on the forum section (left side near the bottom) there are quite a few equine genetics gurus on this site.

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[onthespot]

Impressive isn't the only horse in history that ever had HYPP, just the most prolific, with documented offspring. There are other horses, QH and otherwise with HYPP but it is uncommon. HYPP has spread to may other breeds that accept QH blood, as well as untold hundreds of HYPP positive foals sold unregistered for whatever reason, now there is a high enough risk in the general stock type grade population that I would test ANY horse I bought, be it Paint, QH, App, Pinto, or grade or just looked like a stock type or running type horse. The test is only $25, not worth risking buying or breeding an HYPP positive horse if you don't have to.

 

[onthespot]

Quote:
Can you post pics of both parents? (Wet your mare to make the pattern show up.) Thanks. Then we will all be ready to tell you our opinions of your chances for color, I'm sure!

 

[sbarab]

Here is the link for the prospective sire. http://www.khartoonkhlassic.com/

 

[bkreugar]

Yes that is the stud I am interested in. Sorry I had the name wrong.I do have pics I can post of a few weeks ago at a show BUT you would have a hard time seeing the grey/white on her.Better that I wait till tommotrw and wet her down and THEN post you pics.

 

[Cara]

AQHA's HYPP FACT SHEET

• Hyperkalemic periodic paralysis (HYPP) is an inherited disease that leads to uncontrolled muscle twitching or profound muscle weakness, and in severe cases, may lead to collapse and/or death.

• HYPP is listed as a genetic defect in AQHA's rules, along with Parrot Mouth and Cryptorchid conditions.

• To date, HYPP only has been traced to descendants of IMPRESSIVE, #0767246.

• Having negative (N/N) results on file may prevent a horse's offspring from being tested.

• Foals born in 1998 and later and tracing to IMPRESSIVE will have a statement placed on their Certificates of Registration that recommends testing for the condition unless test results indicating the foal is negative (N/N) are on file with AQHA.

• AQHA will test any foals who are required to be parentage verified and who trace to IMPRESSIVE for HYPP prior to them being registered. This testing will be performed with the same DNA sample submitted to the laboratory for parentage verification.

Tufts Cummings School of Veterinary Medicine

Occasionally, as with the Impressive mutation, the consequences are enormous. As far as we know, HYPP is only seen in horses that have inherited the gene for the disease from Impressive's bloodline. That is why we generally see the disease in Quarterhorses and horses that have Quarterhorse blood, such as Apaloosas, Paints, and Palominos. As fate would have it, not only did Impressive have a genetic mutation for his muscle sodium channel, but he also had an outwardly very desirable trait - his musculature - that resulted in him being a leading sire, thus, by the early 90s, over 50,000 Quarterhorses had Impressive inheritance. So, Impressive's physique was, in a way, a Trojan horse that allowed a huge and consequential flaw to be transmitted to a large number of horses.

www.horse-genetics.com

It seemed that Impressive would go down in history as one hell of a horse: Impressive by name, impressive by nature! And then tragedy struck when Impressive was linked to something altogether more sinister: his genetic legacy included a genetic mutation recently implicated in the rare muscular disorder known as known as hyperkalemic periodic paralysis (HYPP). Although he never exhibited symptoms of the disease himself it gradually it became evident that many of his descendants were inflicted with the painful, alarming and often fatal disease. The disorder has never been observed in horses of other lineages.​

 

[onthespot]

http://www.vgl.ucdavis.edu/services/hypp.php

As noted above, the DNA based test for HYPP identifies the specific genetic mutation which we now know exists in descendants of "Impressive". We presently do not know whether different genetic mutations in other bloodlines also cause HYPP, and the DNA test will not identify other such mutations. Further scientific research is required as to other bloodlines. We presently recommend that all descendants of "Impressive" be tested for diagnostic, treatment and breeding purposes.

http://www.medi-vet.com/prod-Acetazolamide_250_mg___100_Tablets-3315.aspx
HYPP is associated with horses of heavy musculature, but this does not mean that all horses with well developed musculature are afflicted with the disease. The mutant gene causing HYPP presently has been identified in the descendents of the horse "Impressive." Research has not yet been performed on other bloodlines to ascertain whether the same or similar genetic mutation existing in other bloodlines also may cause HYPP. Since "Impressive" descendants are so numerous, the genetic mutation in the bloodline is widespread. Theoretically, it is possible that other mutations causing HYPP in different bloodlines may be more difficult to identify because they are not so widespread.

http://www1.agric.gov.ab.ca/$Department/deptdocs.nsf/ba3468a2a8681f69872569d60073fde1/748814acc30209718725714600515373/$FILE/hypekalemic_periodic_paralysis.pdf
Hyperkalemic Periodic Paralysis Disease is a known disease in Quarter horses, that can be traced to Impressive who was the first Quarter Horse to be the World Champion Open Aged halter stallion in 1974.2 It is not yet known whether HYPP exists in any equines outside of Impressive’s progeny. The HYPP gene became widespread after breeding programs sought to produce heavily muscled horses like Impressive.2

No one is looking for it anywhere else. I know of two horses that were not impressive bred that tested positive. All everyone said was "their papers were obvously switched" and left it at that because they were geldings no one thought it was important enough to track down.​