X&X or Y&Y chromosomes?

severnmiles

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Anyone with a horse that has X&X or Y&Y chromosomes? I phoned up about a horse for sale about a week ago that was like this, does that make it a haemophrodite? I know you can't breed from it.
 

Governor

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Don't own one personally...although he can be a bit poofy, so I sometimes wonder!

However I know there was one up the road from me. He/She/It had male bits and female bits but no uterus/ovaries. Apparently He/She/It was pretty successful at dressage and had no other problems.
 

meandmyself

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There was a pony on horsemart like that not so long ago. Someone posted it on here so a search would likely bring it up. Might be something useful in there.
 

wench

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From my biology days at school.... two x chromosomes is a female and xy is male... so a yy could not be a haemaphradite surely?
 

EllieBeast

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XX chromasomes is just a normal female. XY is a male. so there is no way of getting a YY chromasomed horse, as this would mean that each of the pair came from a male parent. and, of each chromasome pair, one comes from the mother and one from the father. YY is an impossible combination.
Sarah xXx
 

starsky

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Hi Elliebeast is right. You can only have XX or XY. A female carries XX so only passes on an X a male has XY so can pass on an X or Y resulting in offspring being XX (female) or XY (male). You can't have YY as the mother doesn't have a Y to pass on in the first place. Hope that makes sense
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EllieBeast

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Exactly, so XX isnt a hamaphrodite (sp!) just a normal Mare!
hamaphrodites are a product of too much or too little hormones in the womb.
Sarah xXx
 

severnmiles

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You're all confusing me with the X's and the Y's!! Easy I know
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This mare doesn't have a female chromosome, it can't have foals and cannot be mareish due to this....what does that make it?
 

aran

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Found this on Horse Karyotyping:

The most commonly encountered chromosomal abnormality in horses, XO Gonadal Dysgenesis, was first described 1975. Mares with this disease lack one of the pair of sex chromosomes resulting in a 63,X karyotype. The mare is presented as an infertile female, usually small in size for age and breed, with small, inactive ovaries. The condition is similar to a well-documented condition in human females known as Turner syndrome. The prognosis for fertilty is extremely poor. The origin of the defect is probably an accident in development, not an inherited problem. The syndrome has been diagnosed in diverse horse breeds throughout the world including Thoroughbred, Arabian, Welsh Pony, Tennessee Walking Horse, Standardbred, American Saddlebred, Paso Fino, Belgian, Quarter Horse, Appaloosa, as well as in grade horses.

The second most common finding in infertile mares with inactive gonads is the karyotype of a male horse (64,XY)(XY Gonadal Dysgenesis, XY Sex Reversal, Testicular Feminization). Such mares are of normal or even large size and may have successful show and performance careers prior to being sent to stud. The problem may have a genetic origin. It has been encountered in Arabians, Thoroughbreds, Quarter Horses, Appaloosas, Morgans, Standardbreds and a pony of unknown pedigree. Fertility has been reported in XY mares, but is extremely infrequent.
 

druid

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Could be progential adrenal hyperplaisa (CAH). Basically - females w/ clitoral enlargement (looks like penis) - it's then down to hormones what sex they are. That's realtively common.

True Haemaphrodite - xx and xy in deifferent tissues. Which tissues depends on when onset occured in development.

You can get xxy or xxx but these are very, very rarely cross gender - usually result in other heridtary syndromes.

(Couretesy of mother dear the geneticist)
 
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