X-factor

[Sylvie Hebert]

i leased out an older mare to a racing/barrel breeder.she is going to Rare Bar QH.it seems he got told that this stud his a large hearth carrier and is asking me about my mare X-factor...Anyone here can tell me if Brin d'acier TB is or not a carrier...?

[DDT]

Sylvie Hebert

Assuming that the X-factor theory is correct, your mare has two X chromosomes, one she received from her sire, Northern Viking and one from her dam, Apalachial. There is no way of knowing if the X received from Northern Viking is from Miss Disco, but if it is it could contain the X-factor. If the X she received from her dam is that of Moccasin it also could contain the X-factor, so the answer is yes, your mare could have an X chromosome that carries the X-factor.

There are some that believe that the trait is recessive in the female, so if you had the mare examined and she does exhibit a larger than normal heart, chances are she has the X-factor on both of her X chromosomes and in theory all of her foals have a chance to exhibit a large heart. If she is a double copy mare, both X chromosomes carry the X-factor, and the quarter horse stallion is a large heart carrier, the foal will exhibit the trait whether it is a filly or a colt. In theory, the QH stallion will never pass the X-factor to his sons because the X-factor is carried on the X chromosome and all of the sons receive a Y chromosome from the sire, only the daughters receive his X chromosome, so, even if your mare does not carry an X-factor X chromosome, if the foal was a filly it would still have a chance to exhibit a larger than normal heart because all of the stallions X chromosomes carry the X-factor gene and one of the foals X chromosomes would come from the stallion.

DDT

[Sylvie Hebert]

thank you very much.

[xfactor fan]

Sylvie,

You might want to google X-chromosome inactivation. Or look it up in Wikipedia.

In short females have only one functioning X the other shuts off. So if the large heart gene/genes are on the X, a mare could have copies of two different size hearts, but express only one.

Lots of complicated things going on in genetics these days.

[Sylvie Hebert]

Last week we had an echo done at the university with measurements and the vet said she has a giant hearth and very slow hearth beat at rest and on the treadmill very good capacity,he said she must have been a hell of an athlete...she is 20 yo...Strange things sometimes...well even with a big engine you need good wheels...She still moves like a million bucks and her babies sold from $5000 to $12,000. on size,looks and movement(she throws carbon copies of the daddy,any daddy, but with her wonderful movement and sweet temper.)and she is a good mom,lots of milk,take care of her foal and any other mare foal too,easy keeper,catch on one cover...So it might be her last foal,and this will be my last horse to be raised for me as a retirement project.That mare is not for sale anyway,i promised her that when she broke her leg(my fault) at AC years ago,and she paid her way more than once.