Thank you @mvp for that detailed and dumbed down explanation.
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What? If this is a case of simple dominance with only one allele involved, I don’t think your numbers match what a Punnett Square written out would produce.
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Mostly 
Speaking just to Point 1 - What’s left out of what PoV is “they reason that if it’s not benefiting the animal in the long run”.
I actually think there are 3 different scenarios:
- benign (such as Frame overo/OLWS/LWOS)
- benefiting (such as what HERDA might be)
- harmful (such as HYPP)
The problem right now is we don’t know which of these categories WFFS falls into. It appears it’s benign. That really is the most likely scenario, but the benefit/harm categories haven’t been ruled in or out yet.
What I see “on the street” is that a lot of people are stepping up and testing their breeding stock. A lot of horses being tested as still fairly young. Until we have a database of carriers with a significant number who are old enough (let’s say older than 10 and ideally older than 15, just my personal opinion), we can’t begin to track anything that might point to some increase in injuries (especially of related types). And if in that time frame we continue to produce more carriers, regardless of them also going into the breeding stock pool, we could be producing more horses who have an unfair increased propensity for injuries.
So for me, and I know for others, we are concerned about the individuals themselves, but from the perspective of it harming them. Obviously we can’t fix the existing carriers (if only!), but we’d like to also not produce more carriers, at least for now.
I personally consider the WB breeding pool to be large enough that there isn’t any need to work to eliminate WFFS, IF, big fat huge IF, it comes down to it being truly benign and IF registries ban all registration of foals from 2 carrier parents.
If the APHA would ban registration of foals from 2 nO parents, that would do a lot towards reducing the number of LWO dead foals 
But they don’t, so irresponsible breeders take the chance and breed them together anyway.
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Exactly - when breeding for a specific type, you’ll loose heterogeneous aspects in the population – which is why, exactly, some people think that WFSS and the breeding of carriers (of any defect) is a bad idea.
Principally, it’s a very bad idea to continue to breed carriers – because not only does it infiltrate the population quietly this way with no outward sign of a defect, but it is extremely costly to breeders - the diversity is bred out by principle of lost stallion/mare prospects … which is, IMHO, a crime when you consider a good mare can only have a handful of foals a year… so it narrows the population down in more than one way, because good mares are wasted and might as well have been open that year in terms of what they brought to the genetic pool…
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Wow! How interesting! Are there any pictures of the foals? I found a few articles (like this one, HA: Shellscrape has No Tail to Tell After Failed Stud Career) but nothing has any photos.
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I think this is one; https://www.breednet.com.au/gallery/showimage.asp?galleryid=0&imageid=2688&sire=Shellscrape
One of these has the shortened tail too I think…https://twitter.com/BorderBldstk/status/700488674123784192
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From Canadian Warmblood
[h=6]Canadian Warmblood[/h] 17 hrs ·
STATEMENT to CWHBA Members regarding Warmblood Fragile Foal Syndrome (WFFS)
Earlier this month, the CWHBA was made aware of the genetic disorder Warmblood Fragile Foal Syndrome (WFFS), following the announcement by a USA breeder of withdrawal of one of their stallions from their breeding roster due to him testing positive for the recessive WFFS gene.
WFFS is an inherited systemic connective tissue disorder characterized by extreme skin fragility resulting in tearing and ulceration, especially at the joints, from normal contact with everyday surroundings. Unfortunately there is no cure and affected foals must be euthanized soon after birth. Since WFFS is an autosomal recessive trait, a foal can only be affected when it inherits the recessive gene from both parents. A single copy of the gene can be “carried” through many generations without WFFS being expressed.
WFFS was first reported in the Journal of Veterinary Research in 2015, about a foal born in 2012. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4327794/ This is still a rare condition, with very few reported cases as there appear to be very few live births.
The potential impact of WFFS and recommendations going forward, require facts and data. Members may wish to talk to their Veterinarian and consider testing their breeding stock for the recessive gene to determine any that may be carriers in order to avoid carrier to carrier breeding. Testing could apply to frozen semen as well. At present, only one Laboratory In North America, Animal Genetics Inc., in Florida, has a commercial test available for detecting this recessive gene. http://www.animalgenetics.us/Equine/Genetic_Disease/WFFS.asp
The American Hanoverian and the KWPN-NA have both been in communication with their European studbooks, as well as mounting internal task force in North America on WFFS. The WBFSH will be addressing hereditary disease at their annual meeting this fall.
The CWHBA acknowledge and appreciate member concerns. We will continue to monitor the available information, and actively seek more from our own Veterinarian teaching & research centers. We encourage our members to have open dialogue with the CWHBA association, and their veterinary community.
For more information on WFFS, these are links to some information on this rare genetic disorder –
• https://thehorse.com/…/first-case-of-herda-like-disease-in…/
• http://equiseq.com/…/h…/warmblood-fragile-foal-syndrome-wffs
A quibbling point, but I’d say that “carriers” (read: heterozygous individuals) were better than “fine.” Rather, they gained some of the excessive muscling given by HYPP… without it killing them. So breeders had a bona fide reason to want to continue to breed those heterozygous horses.
I am not sure that the gene responsible for Fragile Foal Syndrome confers any selective advantage when in its heterozygous form. But the HYPP example does mean that until you know the phenotypes produced by each possible combination of the gene, you won’t know how much breeders “ought” to care about losing the recessive allele.
Thank you for wading into this thread… lots of issues in this tangle, boy-howdy!
And what I’ll say next should in no way take anything away from the immense respect I have for you all at Hilltop Farm are doing to be transparent and responsible early. This doesn’t happen often in the history of modern, commercial breeding in the US; well done!
That said, can I make the suggestion that you not allow anyone to minimize the seriousness of this problem by speculating about a very low frequency of this allele in the interbreeding population… all because we can’t decide just “what counts” as the population?
I say this because
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I have a tad of technical background that lets me begin to appreciate how hard it is to decide on the size of a closed, interbreeding population in theoretical terms. I think the open-ness of WB registries (in comparison to closed books/breeds like Jockey Club Thoroughbreds or AQHA horses) promises to allow people to argue that the recessive allele’s frequency is much, much lower in theory than it will be in practice. This has to do with the methods of theoretical population genetics. It also has to do with the fact that the group of horses that have been identified as possessing a recessive allele is probably limited to a few lines. But you’d have to know so, so much about the breeding patterns of these animals overtime within the population of all possible pairings in order to figure out just how small that “functional” interbreeding population is and just how high the frequency of the allele in it is. Suffice it to say that by the time you consider the horses likely to be crossed with elite WBs found to be carriers of the recessive allele, is frequency in that smaller population will be much higher.
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Deciding just how small/genetically homogenous/inbred a population is has substantive political and economic meanings attached. I think I recall a horse geneticist at Cornell telling me that some population geneticists had tried to estimate the amount of inbreeding/lack of genetic variation in North American TBs and disagreed a bit on their method. It would be a very technical, quantitative discussion indeed! That difference, which few outside the field might understand, of course, had major import for breeders who either had to believe that the supply of variation was getting exhausted (and there wouldn’t be a great fix for that without opening their book) or it was not and TB breeding could continue merrily along as it always has.
As you can see, there are ways---- rhetorical and perhaps, technical and quantitative-- to make the problem of a deleterious recessive allele into a big problem or a small problem… depending on what you can make people believe about the size and breeding structure of the population.
Just my .02.
Thank you! You are a better googler than I am :lol: 
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Some of them did, some did not. Some nn horses had bigger muscling, others did not. They were rolling the dice with a terrible disease on the chance that they’d get a foal with enough muscling to win early and often, before symptoms started showing up. And the fact that more nH horses than not either didn’t have symptoms (that were a problem), or had them mildly enough they could turn their head and ignore, just further fueled that purposeful breeding of HH horses.
I am not sure that the gene responsible for Fragile Foal Syndrome confers any selective advantage when in its heterozygous form. But the HYPP example does mean that until you know the phenotypes produced by each possible combination of the gene, you won’t know how much breeders “ought” to care about losing the recessive allele.
Exactly.
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Not all N/H horses gained the excessive musculature of Impressive and many were sold on for non-halter use. Thus many unsuspecting people ended up buying N/H horses for use in (non-cow) AQHA performance events, 4-H, and as trail horses. Meanwhile HYPP spread into the color registries and into crossbreeds. HYPP did kill many of them, just not as foals.
I wish I could say that I am surprised at the fact that N/H horses are still being bred, but the disastrous handling of this defect by both breeders and the AQHA from the beginning, makes this unsurprising. It shows that people will continue to breed horses irresponsibly over a very long span of time.
I’d like to think that most breeders are responsible. Among the breeders I have known, they have been responsible but one only has to look at the HYPP debacle to know that there are great many who are not.
Hilltop is an example of what good breeders do. Identify the problem, take advantage of genetic testing and take preventative action, in this case waiting for more information.
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I’ve only got a small nit to pick about the announcement from Canada. WFFS was not first reported in 2015. Maybe that’s when the peer-reviewed article was published, but Dr Winand’s patent application to identify the mutation was made in 2011. (https://patents.google.com/patent/WO2012158711A1) and the test was commercially available in 2013.
We had a long discussion that involved WFFS in 2013 (referenced upthread).
It’s just that Hilltop’s announcement has gotten WFFS a lot more publicity all of a sudden.
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Just to add, for clarify, the article linked by the Canadian report states:
"This is the first report describing the clinical and histopathological findings in a foal confirmed to be homozygous positive for WFFS. "
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great post!! IMO HYPP is a very sad example of handling a disease wrong. There was not enough information available to everybody to make educated decisions. But on the other hand, HYPP has a completely different way of heritage so I have problems to understand why some people need to use it as an example all the time in this thread. WPPF is something very different and IMO can be handled in a different way.
What do you mean these diseases have “a different way of heritage”? I’m confused. How are they different?
One thing they have in common is a very simple genetic basis… so simple, in fact that folks are describing them in Mendelian terms. I am not sure whether or not both of them obey the law of dominance, where that is complete. Also, I don’t know if anyone has found that the heterozygous condition has some appreciable (and even desireable) phenotypic trait associated with it. Someone suggested that the looseness we see in big-moving horses might be what that looks like. I have no idea, but i think it would be interesting to find out.
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It’s been clearly explained a few times why HYPP has been used as an example of what can happen.
In the beginning, nobody knew that the hetero form also caused the disease, because not only did it usually take longer for symptoms to appear, not only were those symptoms often much more mild than the HH from and easily attributed to “he worked too hard”, but many nH horses never showed symptoms. It’s all those reasons why people continued for too long to think that nH horses were just fine.
Until they realized they weren’t.
That is why many of us feel it’s prudent to be cautions about blindly being ok with carriers producing more carriers right now. We don’t know how or if it affects horses as they get older.
HYPP the disease is only partially different, not completely different, from WFFS in that the hetero WFFS horse does not have the actual disease, where the hetero nH horse does still have the disease, just a milder form of it (but nH horse can and still do die as a direct result of seizures, so don’t think it’s only about muscles or tying up).
Inheritance of the genetics still works the same way.
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Yeah, or more precisely, the genetic cause of these two diseases are miraculously simple. Heck, there don’t even seem to be two genes involved! That means any one of us can pull over and google up a Mendel tutorial, remember what a Punnett Square is and have the pattern of inheritance for all three possible genotypes figured out. Thinking about this over more generations gets a tad more complicated, but not a whole lot.
Really… it’s so rare that a significant phenotype has such a simple kind of genetic cause.
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Because I am an old fart, I do want to also throw this idea into the discussion about what people did or didn’t do about genetic issues in the past. Both for SCIDS in Arabs and HYPP in QHs, and probably other diseases, genetic testing or even widespread awareness of genetic issues just did not exist in the 1970s or 1980s. Oh, and no internet! So just imagine trying to put together the pieces of the puzzle for these issues without those resources.
That does not excuse in any way the lack of action once the issues were understood.
I am hoping that the warmblood registries can learn from others’ mistakes. But, it is not a good sign that WFFS has been known for 5+ years and we now have one breeder who announces testing of their stallions. Good for them, but where were they in 2013? And why didn’t the registries do something once the issue was known in at least 2011?
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In her defense, Manni is not a native English speaker. I am pretty sure she meant inheritance, meaning hetero and homo zygous
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