Merle gene test is invalidated

This is actually old news, but it’s worth repeating so everybody understands it. There are a TON of nonsensical statements being made in many breeds, often based on merle gene testing, and these all need to be taken back.

When you click on the link to get your dog tested for merle, http://www.genmarkag.com/index.php, here’s what you get:

Picture 3

Yep, the “merle” test is dead.

I don’t know the exact story; I’ve heard that the gene they decided was merle (SILV) actually turned out to be for a form of piebaldism. That would make a lot of sense, because I’ve seen pictures of the dogs they decided were single and double merle and the single merles have a ton of white markings. Color authorities have been saying for years that it can be difficult to tell the difference (by sight) between double merle dogs and piebald dogs, and evidently genetic researchers couldn’t either.

Here’s the study that absolutely clinches how terribly wrong they were, in my opinion:

http://www3.interscience.wiley.com/journal/121677286/abstract?CRETRY=1&SRETRY=0

The short story is that they tested a bunch of dogs to correlate the double merle pattern and deafness, and they found that two doses of the SILV gene equaled deafness in about 15% of the dogs tested.

Clearly, nobody on the board was a breeder of merle dogs, because ANYBODY who breeds merles could have told them that true double merles are deaf probably 95% of the time. The number of double merles I’ve ever seen or heard of that can hear well? MAYBE one or two. A handful more have partial hearing. But I come from Danes, where merle to merle (harlequin to harlequin) is an incredibly common breeding. There are lots of white dogs around and virtually none can hear. There’s a white Dane boy whose breeders claimed he could hear, but he also could have been a piebald and not a double merle. I know of zero double-merle Aussies that can hear; I know of a couple double merle Cardis with partial hearing but none that have 100%.

According to that study, if SILV was the real merle gene, we should be getting 85% normal-hearing or unilateral-hearing dogs.

Which (WOW) just ain’t happening.

The real tragedy of this fact is that breeders and breed clubs have been making all kinds of wild claims based on the result of this faulty merle testing. The Chihuahua Club of America is basing all kinds of their campaign to disqualify merle on the fact that they have unhealthy dogs who were tested as “single” merles. The same study up there found that “single merles” had a rate of unilateral and bilateral deafness that approached 10%. The researchers found all kinds of eye and ear abnormalities in dogs that were tested to be single merle (i.e., “normal” merle), and therefore implied that the whole color was a ticking timebomb of horrible health issues. The fact that they were testing the WRONG THING has not been made public and the CCA and other breed clubs have not recanted their reasoning for banning or attempting to ban the color. And a whole bunch of breed clubs’ health pages still list that dead link as the source for merle testing.

So spread the word – it’s actually good news. If that HAD ended up being the correct gene, we’d all be scratching our heads and trying to figure out why the researchers were telling us that our dogs were all unsound when we were looking right at them and they were fine.

Clue says, “I can hear just fine. Too well, actually.”

IMG_0339

Advertisements

14 thoughts on “Merle gene test is invalidated

    • Yes, it does, doesn’t it?

      The way gene identification works in these kind of things is that they figure out four or five genes they think are candidates, based on what they see in dogs identified as what they’re looking for (whether that’s double merle, or PRA, or whatever). Think of the possible ones as green, yellow, red, and white.

      Then they go test as many positive dogs and negative dogs as possible, looking for the one color that is always found in all the positive dogs and never found in any of the negative dogs. If they find that green is showing up in all the dogs identified as positive, and there are no green genes in any of the dogs identified as negative, they say green’s the one.

      The real difficulty in this is that it relies on a subjective identification (of the dog as a particular color, or of the dog having a particular disease) to make the genetic determination. If one of the green-gene dogs didn’t actually have PRA (instead had a similar eye disease), or wasn’t actually double merle (was piebald or a piebald carrier, for example), green can be identified in error.

      That seems to be what happened in this study; they thought they had all double merles but in fact they had double-merle piebalds. Which is exactly what you’d expect, since most of the merle breeds also carry piebaldism and breeders looking for flashy chrome on dogs often unconsciously select the piebald carriers.

      And yes, the elephant in the room is certainly DM. Time will tell. Right now I’m very concerned, as I have been since the first results started to trickle in to OFA. Genetically, this is an epidemic, with the majority of all dogs of all breeds testing abnormal. But it’s a disease most breeders had never even heard of, much less seen ravaging their breeds. So either we have a disease that only rarely moves from genetic to actual, or we have an incorrect gene identification. We probably won’t know for at least ten or fifteen years, which is why I will test but not make breeding decisions until we have at least one full birth-to-death generation being tested and observed.

  1. There are a select few double merle rough collies right now that their breeders CLAIM have 100% hearing… hmmm… makes you really wonder what is true and what people want to be true 😉

    • I think it’s entirely possible to have SOME hearing in a double-merle dog. If the dog has full hearing, I’d suspect that it’s a single merle + piebald (i.e., a “white”). Either that, or a complete fricking miracle, and its occurrence is not likely to be in any way predictable.

      I actually don’t know why full hearing is seen to be an advertising point for some reason. The dog is going to be bred to black or tri bitches, none of the puppies are going to be double merle, so it doesn’t matter whether he’s deaf as a post. If he’s a good breeding candidate, he’s a good breeding candidate.

  2. awwww, she looks so yummy sweet in that picture! ❤ I love stuff like this even tho genetics is one of those subjects that make me very dizzy. (I once sat in on my oldest sister's Master's level Genetics class, I was 16 and lemme tell you I was relieved to look around and see all the students looking as confused as I felt!)

    Speaking of genetics, I thought I remembered reading a few years ago in some reputable science journal that human eye color is determined by three genes, not two as had been thought for many years. Is that true, or am I remembering wrong? or is it still being debated? I figure with all the reading you do on genetics, you may have encountered the latest on this. And I want to be polite and bring it back to dogs so: is it known how many genes determine eye color in dogs?

    I lovelovelove merle dogs, dogs with heavy ticking, and "blue" dogs. *sigh* My Ellie's pretty heavy on the black, so the next BTC we get has to be more blue-ish.

    • This got dumped in my spam file accidentally – no idea why. I dug it out and approved it, of course, but sorry for the delay!

      Eye color in dogs is interesting. What in humans is just called “brown” is divided into probably a dozen shades, from berry black to light amber, in the parlance of dog breeders. I don’t know that anyone’s ever made a real study of it, though I do think that the lighter eye is easier to get. You have to really work at maintaining the dark eye if you want it.

  3. Facewise, Clue is almost as pretty as her brother with the wonky blaze in Ar. Bodywise she is a whole lot prettier and bigger. I love reading your blog. I am learning so much!!!

    • And she’s so tiny! I call her my pocket Corgi. But I know, her bro is like a little bolt of lightning.

      Someday I’m going to corner Betty Ann and make her tell me everything there is to know. I would LOVE to know if the littleness comes from Rooney or if it’s Lala’s side.

  4. On the Chi lists, the merle test was debunked through testing merle Pomeranians. Very obviously merled Poms, with no white, were resulting in mm results (non merled)

    My opinion as a Chi fancier, is I’d rather see the CCA freaking out over bad knees, and other health issues. Many of the merles, are having some of the best health testing results in the breed, as well as some excellent movement in the breed. Napoleon, a LC merled Chi, is one of the top LCs in the US. Very, very nice dog. Personally, I can’t see that, and be color biased, even though I’m not personally a merle fan in ANY breed. (I much prefer brindles, sables, and chocolates *G*)

    I do hope someone will come out with an accurate merle gene test. It’d be VERY helpful for cases with ‘hidden’ merles, such as some sables, or brindles, and those light ee red dilutes. A merle test would be VERY handy, for a lot of breeders who cross color breed, but also don’t want to breed merle to merle litters.

    • Wow, that’s kind of a huge oops on GenMark’s part.

      I know that they patented the test or the gene marker somehow and were very snitty about sharing it, which was (reading between the lines of some rather terse text) quite annoying to Dr. Schmutz and the others who are working on color. So I guess their bad deeds bit them in the tail in the end.

      At the risk of beating a dead horse on color: Merle is ONLY HIDDEN BY ee RED. You can CLEARLY see merle in red/fawn/sable and you can see it like crazy in brindle. A very, very few reds/fawns grow up to be so light that you can’t see it in the adult coat, but you can always see it on the baby coat. Unless a breeder is so uneducated that they don’t bother to find out why their red puppy is covered in splotches all over its body, there’s no danger in missing a merle. The ee red is still pretty rare in merle litters, but an easy solution if you have an ee dog who was born in a merle/black litter and you don’t know whether it is merle or not is to test breed it. Just assume it’s merle and make sure the first breeding is to a black or brindle or red. If you get merle puppies, you know your ee is a merle. It’s not rocket science.

      And, honestly, white dogs are not the apocalypse. They’re really not. Some of them force you to make really hard decisions if they turn out to have eye abnormalities, but the world doesn’t end. And most of them, while deaf, can lead perfectly happy lives with committed owners.

      • In Chis, ee red is rampant (Esp with the ‘chinchilla’ dilution), and I do know of a ‘hidden merle’ brindle Chi (Well, he’s passed away now), who’s breeder hadn’t labeled him as a merle so it was found out later by his owner.

        Merle ee reds isn’t a big huge issue in Cardis, like it is in Chis, and Poms. That’s why so many Chi, and Pom breeders are so aggressively against the merle gene, esp since they also have piebald spotting in those breeds too.

        I agree in a way that homozygous merles aren’t the end of the world, but on the other hand, I personally share the opinion of many breeders, that it’s better to simply avoid producing them. If one health problem can be completely avoided, by not breeding merle to merle, I’m all for preventing that one problem. There’s already enough crap that can go wrong in litters, I personally don’t want to up my risk of heartache, personally speaking.

        In rats, our pearl gene (Most common color base for rat merles) is homozygous lethal in utero, which I can completely handle, but having babies in my hands, it’s hard to loose them for me. That’s all personal opinion, and a personal opinion held by many which I can truly respect. Not everyone is willing to choose to take the risk of defective puppies, even if it’s a general risk in breeding. Everyone has their own comfort zones.

  5. I know of a couple full hearing (confirmed by BAER test- they were tested in rescue to determine whether they needed to go to the special needs foster or not) double merle collies. I also know two partially deaf CHW single merles from that same group of dogs. (Mill shutdown.)

    I also have a non-merle collie who is pretending ot be deaf this morning in order to continue supervising the neighbors’ children in their pool rather than come inside.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s