Dog Genome Project: Double-muscling In Whippets, Call for Sample Submission Options

[jensen]

As far as bulls in American pedigrees goes i would venture this may have more to do with English non ped blood in the breeding rather than a spontaneous mutation.

Whether the condition is caused by a single gene is IMO equivicable. Whippet racing is a power sport as it is a sprint race and clearly well muscled dogs are an advantage and do well and hence are used to breed from. Its plauable that the gene is recessive but partialy expressed ( rather like sickle cell aneamia) and confers an advantage when a single autosome is present but when both are the recessive gene a bull occurs. Why there is also commonly skeletal defects is more difficult to explain.

The fact is, it doesn't really matter how it got into the bloodlines. What is important is that it is there (and also in the European pedigree bloodlines...probably through a Good as Gold daughter imported to France).

In the case of the German boy, both of his parents carried one copy of the mutation and were both known for their athletic ability. If two people in Germany can find one another and have a child together, it's not unreasonable to allow the possibility that there is more than one source of the mutation in the whippet population. I have not been able to identify a common ancestor in the American lines producing bullies, even if I consider all the rumours.

I absolutely agree with your hypothesis that a single copy of the gene likely confers an advantage and a double copy creates a bully or a "bully lite".

This is a copy of the initial letter sent to the NIH's Ostrander Lab:

I am writing to inform the NHGRI Dog Genome Project of an apparent genetic defect in a sub-population of pure-bred whippets. It is hoped that your researchers will find this a worthwhile research pursuit.

Several lines of whippets bred for racing are now producing what are known as “bully whippets”. Bully whippets are characterized by extreme over-muscling (to the point of being considered double-muscled), severe overbites, protruding tongues, overly broad back skulls, cat feet, short limbs, and noticeably sweet temperaments. A bully whippet does not look like its littermates or its parents but it does look like other bullies, much in the same way that people with Down’s Syndrome have similar physical characteristics.

Anecdotally, we have heard that the “bully syndrome” also occurs in NGA greyhounds and non-pedigreed whippets in the UK. Like the pure-bred whippets here, both of these populations are bred for racing.

A number of breeders and enthusiasts have worked together in an attempt to identify the source of the problem and we have developed an admittedly amateur theory that could explain it. If any part of the theory is correct, it could prove interesting to not only those involved with canine genome mapping but also to researchers studying myostatin mutations and muscle wasting diseases and/or those researchers studying Down’s Syndrome.

Our theory is based on our observations of the different breeding lines producing the bullies and a layperson’s knowledge of genetics. Simply put, we suspect that a spontaneous myostatin mutation has occurred at some point in time in the racing whippet population and, when a male carrier of the mutation is bred to a “geriatric” female carrier, a Down’s Syndrome-like affected pup occurs.

When breeding for athletic performance, whippet breeders generally breed “the fastest to the fastest”. As suggested by the family history of the German boy recently found to have a myostatin mutation (NEJM, Myostatin Mutation Associated with Gross Muscle Hypertrophy in a Child; Schuelke, Wagner, et al.; Vol. 350, No. 26), a single copy of a myostatin mutation produces athletic prowess. We theorise that, for several years, whippet breeders have unwittingly been selecting for a singly copy of a myostatin mutation in their breeding programmes. Aside from being fast, there are no other physical traits that might suggest a whippet is carrying the “bully gene”.

Occasionally, these very fast whippets have produced very heavily muscled pups that share some of the characteristics of the “bully whippet” but not all. For lack of a better word, we have been calling these whippets “bully lites”. In our theory, these “bully lites” are analogous to the German boy; they carry two copies of the myostatin mutation.

That left us wondering where the true bullies were coming from. The overwhelming similarity to Down’s Syndrome (and other aneuploidies) led us to consider the age of the mothers of the bully pups. We identified different bitch lines that appeared to produce bullies at different ages. It seems that, after a certain age, bitches that had previously produced normal or even “bully lite” whippets, invariably produced bullies.

We suspect that the theoretical myostatin mutation has produced fragility in the chromosomal structure and, after a certain maternal age, aneuploidy is more likely to occur during the development of the embryo.

Perhaps it is only coincidence but one article researched during the development of our theory indicated that the canine gene which contains the myostatin information maps to the human chromosome 21 and aneuploidy in that chromosome is responsible for Down’s Syndrome.

In closing, I hope you will find this an interesting and worthwhile research topic. We are able to provide photographs, pedigrees, and (in some cases) DNA samples of known carriers, suspected carriers, and affected dogs.

For whippet breeders, a more definitive knowledge of the root of the problem could provide crucial information for breeding strategies. I also apologise for any obvious scientific errors in our theory; as I said, it is an admittedly amateur one.

Our hope is that the Ostrander Lab will be able to tell us exactly what is going on with our dogs' genes. I'm not so sure now that the age of the bitch is that crucial; more like the age of certain bitch lines creates fragility at that chromosome.

Hope this explains more...

cheers,

jen

[Joanna]

Well our kit turned up on Thursday and we duly swabbed and measured. It is all very straight forward and the cost to return the large envelope to the US from here was only £4.00.
If you haven't already requested a pack, do consider it. All research is highly valuable and only serves to improve the breed for future generations

[~Helen~]

My kit never arrived...
Did anyone else get involved with this?
I keep wondering about it

[Joanna]

My kit never arrived...
Did anyone else get involved with this?
I keep wondering about it

We sent all our stuff back and got an e-mail to say it was received in the USA. I should e-mail Dana again, I am sure it must have got lost in the post or seized by customs

[DENISE BAILEY]

From what i can gather Cathrine also had Mac (blue goblin + master blaster) none ped sampled, i haven't heard back off her with the findings yet, might send her a email as she has moved back to Norway again she said mac loves it there

pic of mac at 10 weeks

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[DENISE BAILEY]

pic of him just over a year old

This post has been edited by DENISE BAILEY: Nov 24 2006, 07:14 PM

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[DENISE BAILEY]

Can i just add that mac was out of a litter of 4 2 dog 2 bitchs 1 dog (mac) and 1 bitch (eve) both were bully also mac was undershot in the jaw..the other 2 mary and minty are both fine pics of eve at 14 weeks

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[jensen]

This study has just been published:

Double-muscling study

[Cathrine]

I can add some more recent pics of Mac, he is 1 1/2 years old in these.
He is the typical bull whippet!

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[Cathrine]

Typical overshot

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[Cathrine]

one more

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[DENISE BAILEY]

but hes a lovely little boy

[DENISE BAILEY]

Mac mam (Lisa) chilling out tonight



Lisa during her racing years

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[DENISE BAILEY]

Mac's other litter brother (minty) & sister (mary)

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[jensen]

I can add some more recent pics of Mac, he is 1 1/2 years old in these.
He is the typical bull whippet!

And based on that full frontal nudity pose, I'd say the typical boy!