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T O P I C R E V I E W
cookie
Posted - 21 Dec 2009 : 11:35:19 PM Hello, Can anybody tell me where the CA thread has gone ?I dont think I am dreaming,but I certainly cant find it. Thanks jane
23 L A T E S T R E P L I E S (Newest First)
szedlisa
Posted - 30 Dec 2009 : 5:56:40 PM That is the reason for the slight delay then Dom. The Van Haeringen lab collects the hair follicle samples, extracts the RNA from them and then sends the RNA data to the VGL lab at UC Davis. When shipping live animal samples between two official laboratories , the export/import licences and international paperwork is much simpler/ Sort of like sending in a "diplomatic pouch". It also assures that samples do not get lost or broken in the mail. (in case of blood samples). The mails are always slower around the holidays and the labs also give time off for their personnel. <grin>
When sending directly to UC Davis, they require parentage details and for this reason their database of individual known carriers is much more ample than that of the labs in europe. precisely because UC Davis has a longer history of research. The labs are all qualified to find the markers as with the completion of the entire mapping of the horse genome and the updating of the SNAPs programs, it no lomger takes 6 months to find a gene and hundreds of thousands of dollars US. But their database is not extensive.
Just a tip, it has taken months to get the molecular geneticists to describe the process in layman's language <grin> !!!! You are not the only one who has been confounded by their previous description of the scanning process. Lisa
Sirius
Posted - 30 Dec 2009 : 3:56:11 PM I tested through Van Haeringen, on the same basis of better than nothing. I was not at all convinced by the information given on their site, hence my questioning. Your most recent post is the first on AL to give a convincing explanation as opposed to assertion. Thanks again for it.
Dom
alethea
Posted - 30 Dec 2009 : 1:32:36 PM Really sorry to hear about the Justice youngster that has had to be pts. Very sad. RIP.
Lisa, thank you for posting the info on CA, very informative. Alethea Aristotle Arabians
szedlisa
Posted - 30 Dec 2009 : 1:03:56 PM Glad to hear you have tested Dom. Which Lab?
Lisa
Sirius
Posted - 29 Dec 2009 : 11:11:42 PM Thanks for posting this, Lisa. It's much the clearest explanation so far of the test. The labs haven't answered any of the questions put to them.
I must "admit" that I tested the mature stallions some weeks ago, and am still waiting for the results. I'm waiting for the definitive test before I test any of the boys who are not yet mature, unless they mature in the meantime.
Once the definitive test is available, I will test the whole herd including the geldings, and alert any of the owners of our youngstock if there are any suspicious results at all.
There's an interesting assumption about the relative responsiblities of mare and stallion owners running through all of this, but that belongs to another thread!
Dom
szedlisa
Posted - 29 Dec 2009 : 01:29:40 AM All:
Beth Minnich passed the following on to me a few days ago and it readily explains how long the CA mutated defective allele has been in the arabian breed, how that has been deduced, and how the present research (based on Haplotype testing) at UC Davis works as explained by Leah Brault at their VGL laboratory. It also verifies the quality of the present marker scanning test. Please read through it all as it will answer many questions. Understanding how the scanning process works should clarify any doubts as to the accuracy of this testing method.
The basis for haplotype tests is that a particular mutation has a common ancestor. This ancestor is the horse in which the original mutation first arose. There are genetic markers scattered throughout the genome, and this ancestor had particular alleles at the markers in the area of CA. So, for example, if the horse had the CA mutation arise on one chromosome, and he had alleles ABCDEFGH in that area, the genotype looked something like this (overly simplified version):
A--B--C--D--CA--E--F--G--H (chromosome 1)
a--b---c---d---N---e---f---g---h (chromosome 2)
These markers are all close together and the concept is that they will "travel" together as they are passed on. Therefore, when this horse passes on its CA allele, it will pass along ABCD(CA)EFGH, and when it passes on its normal allele, it will pass on abcd(N)efgh. Then, whenever offspring pass on the CA mutation, they too will pass on ABCD(CA)EFGH. The mutation moves with these associated markers through generations
When UC Davis first started looking at KNOWN carriers of CA (known based on production of affected foals,) and KNOWN CA affected foals (known based on diagnosis), they noticed that every affected foal was AA BB CC DD EE FF GG HH, and every carrier horse was A_ B_ C_ D_ E_ F_ G_ H_. Most of these early foals were pretty closely related, and so it wasn't a huge surprise - the assumption was that they were getting it from a great-grandsire or something. But, as more and more affected foals (based on diagnosis) were sent to the lab for testing, who didn't have common ancestors with the first group of foals until nine or ten generations back, they saw that ALL of these foals were also AA BB CC DD EE FF GG HH. That told the researchers that CA has a single ancestral source in the Arabian breed, one that is very, very old. These affected foals are of a variety of bloodlines, including Egyptian, so the CA mutation must predate the division of these "nationality/geographic" subgroups, since they all carry the same marker alleles.
When testing is done, the lab is looking for these alleles--ABCDEFGH. I believe they have found about 40 markers that travel with CA and they test for 15 (so the A-H example is simplified). Although it isn't possible to determine an overall % accuracy for the test, the research shows a very high degree of success. Theoretically, there could be another source of CA in the Arabian breed (meaning a different haplotype would be involved) or there is a very slight possibility of the halplotype they are testing for exisitng in a "normal form" in some horses. I'm not aware of any of these theories playing out as reality, but yes, theoretically it is possible. However, something we DO know is that when two carriers are bred together, there is a 25% probability of having an affected foal - so which odds do you want to go with?
In terms of test results - ALL of the confirmed affected foals tested so far have had two copies of the CA haplotype. They have NOT yet seen a confirmed affected foal that did not carry two copies of these markers. So, the presence of these markers is certainly very indicative of CA. Occasionally a horse is tested with an "odd" haplotype...perhaps it has ABCD, but not EFGH. In these cases, the result is listed as "undetermined". As they continue to narrow the CA region down further and further, some of these "undetermined" cases are being resolved and it is becoming very rare among the rare to get an "undetermined" result now.
In the end, Arabian breeders need to decide whether the very small chance of error is worth it when making breeding decisions. Also of note, people who are testing now (directly through UC Davis, not necessarily through one of the European labs) will NOT need to send another sample when the direct test becomes available. The lab will automatically re-test and let owners know if they obtained a different result.
The indirect CA test is a very valuable tool for breeders, especially for those working with known CA lines. The choice is there to use or not to use....with the primary goal being not to produce affected foals. IMO, that is where the focus should be....no more affected foals.
The use of crossbreeding with untested arabians can and will introduce CA into other breeds. Some non arabian breed registries already have recognized this danger and are requiring that any new arabian infusions are pretested for CA status, prior to acceptance for breeding.
LisaC
barbara.gregory
Posted - 26 Dec 2009 : 2:39:29 PM How very sad; rest in peace, little one, gone but never forgotten.
barbara
M Robson
Posted - 26 Dec 2009 : 1:57:07 PM I forgot to mention before, i have another two videos of affected horses but not sure if i can add them (copyright), they are on Youtube though.
If anyone would like a link to them pleae PM me
x
M Robson
Posted - 26 Dec 2009 : 1:49:18 PM Oh goodness me, how very sad, she was a little gem. I will be testing all my mares and stallion next year.
Well done to Anette for allowing others to view this, this little girl of yours will certainly make a change i am sure.
God bless to you x
SueB
Posted - 26 Dec 2009 : 11:00:22 AM Here is the link to the video of the poor filly PTS.
I hope it's OK to post this? it is not advertising anything or anyone just this very sad video
Posted - 26 Dec 2009 : 01:13:29 AM Regards important topics that have been highlighted in all the forums our plan is to infact be make things like this far easier to find in the future for all, rather than as with some info being lost in the forum over time.
The Panel will hold this topic until the AL Living Library is ready to launch and topics such as this will be reachable from the forum and the AL Living Library.
cookie
Posted - 26 Dec 2009 : 12:15:32 AM Well they have certainly hidden this quite well!!It must be the only forum where you cant find a direct link to it.What worries me is the number of owners of breeding stallions and mares who still have not heard of this.Whether the test is 100% or not, it is the best option at the moment.How anyone can excuse not testing is beyond me.If 1 foal is saved from suffering this dreadfull fate it is worth it. jane
barbara.gregory
Posted - 25 Dec 2009 : 8:37:49 PM Sue, can you put a link to the video up so that we can all see it, please?
Many thanks
Barbara
SueB
Posted - 22 Dec 2009 : 10:28:16 PM Having just read about the Justice offspring recently PTS, I notice they have very kindly put a very sad and short video of the affected offspring up and Anette Mattsson has written an excellent article which they say has been published in the Collectors Edition of 2009.
Well done to Sam and team TAM for highlighting this and taking the subject so seriously.
My point is that it isn't presented by the testers as robust enough for people to think that a "clear" result means that a horse is actually clear. If they are just being scientifically cautious about the test, then with luck my scepticism will be proved wrong.
In the meantime, we should breed to prevent the loss of bloodlines, being as careful as possible, aiming to produce the best offspring we can, and should avoid mating two suspicious horses including tested suspicious. However noone should think that they are not still taking the risk of producing carriers or affecteds just because of the existence of the current test results. Everyone who tests now should retest as soon as the next test is produced, IMO.
we will not test our entire herd yet, as we were going to do, but will be interrogating prospective visiting mare owners very carefully. We may or may not test our publicly standing stallions yet.
This isn't a do nothing stance at all, and our 2010 website has much more information and guidance on genetic diseases. I am very concerned that people will test now, and resist retesting.
Dom
LYNDILOU
Posted - 22 Dec 2009 : 12:22:03 PM Do you know that nearly all humans AND animals carry genetic defects of one sort or another ?, we as a race are not tested for things.! so lets not get this put out of all proportion, all the time animals and humans mate there will be a chance that a genetic fault will occur . fact of life .however we CAN be responsible and test for the best outcome to our future offspring. here I go behind the wall
Sirius
Posted - 22 Dec 2009 : 12:07:51 PM I quite agree with you, SueB. Do nothing isn't an acceptable option. I am 100% in favour of testing.
What I am saying is that the science isn't quite ready as presented, YET.
We should all be gearing up for testing, and I am absolutely going to do it, but the worst case scenario is the surge of confidence that could come from a test that is actually not proven to "protect" against breeding affecteds.
My point about the cost side is that if this test isn't definitive, we will all have to retest when the research at UC Davis produces the identity of the actual gene. Or maybe a better test, then another even better test ...
There was a lot of concern expressed on AL over the publication of the full horse genome: what would the mad scientists do to poor horses now? Well, part of the answer is to be able to identify the CA allele, in due course.
Unless I am wrong, this test won't protect us against CA without sacrificing some endangered bloodlines UNLESS the test is more valid than the current genuine experts are claiming. If there is any possibility of false positives or false negatives the only safe prevention is to stop breeding. I hope that it really is me that is wrong.
I do agree that the CA thread should be reachable through the AL discussion menu if possible, if only via a note at the top of the list of forums.
Dom
SueB
Posted - 22 Dec 2009 : 11:39:29 AM I have read your reply on the other thread Dom.
What other choice is there for us then??? I and I know others who really wish to do the right thing and protect our breed are trying our best with what testing is on offer. What do you suggest we do, nothing,? it is not a good enough option.
At least by doing this test we feel we have done our very best in trying to stamp out a continuing problem. My head spins with worry about some of the foals due next year from mare owners who used stallions not tested.
I know many over the years who have foals die or have had problems and all kept quiet for the sake of one big almighty reason........money.
Sirius
Posted - 22 Dec 2009 : 11:23:49 AM I have just posted my concerns in detail about the validity of the current test on the panel thread.
Yes, we will test for CA,but I don't believe that the test results of "clears" are necessarily valid yet, and I would not be prepared to trust a "clear" to be definitively N/N clear or even a "carrier" to be definitively CA/N carrier.
Please read my full posting before replying to this. This is too important an issue for kneejerk reactions.
Dom
LYNDILOU
Posted - 22 Dec 2009 : 10:52:34 AM I have sent away my sample from Royal Justice Sue , just waiting for the results, he is not affected himself or it would have shown by now , I just need to find out if he is a carrier at least if he is he can still breed to tested mares later
SueB
Posted - 22 Dec 2009 : 10:21:28 AM This is such an important topic, please would it be possible to at least give it a heading so people can see it when they click on "any forum"
I sincerely hope stallion owners test their stallions please. It is their responsibility.
Don't hide by saying " oh no, just another thing to test for".......a Justice youngster has recently been put to sleep as it was affected and nothing could be done for it. So so serious. Same as for Scid. Do the right thing everyone please.
Please read the updated list of stallions and mares that are affected. It is in all lines.
It costs very little to test in comparison with the blame which should be laid at your door if your stallion sires an affected foal, worse still if that foal is not bred by you.
I wanted to add that having spoken to some stallion owners who are nervous of testing, if the result is positive it is not the end of the world for your horse. People will still use him if you insist on negative visiting mares only. Same as for Scid.
Pashon2001
Posted - 22 Dec 2009 : 02:53:44 AM Nothing is where you left it lol!!
Rui
Posted - 22 Dec 2009 : 01:05:21 AM We moved it to the Panel forum:
here I go behind the wall
