The DNA of Merle

 DNA and science do not care about our opinions of preferences. It doesn't care bout our preconceived ides or experiences.  DNA stands on its own in the face of what we think we know. And You do not get to change science because you have letters behind your name. There is a lot of science out there that simple people like me can understand.

Merle is a dilution gene that arbitrarily dilutes the base color in random areas. Dr. Leigh Clark, the leading geneticist in the U.S. discovered this mutation, along with Mary Langevin, worked closely with Vemodia labs (now Tilia in Czech republic) to pin point the different sequences and variations of merle.

Merle is a pattern, a SINE insertion on the SILV gene. Merle is a piece of DNA that works by inserting itself into chromosomes and adds a piece of DNA.

It has a head, body and tail (poly-a tail). The tail contains base pair numbers, while the head essentially "bites down" on the DNA, while inserting itself. This mutation can happen in all mammals. This particular merle SINE insertion disrupts the ability to create normal pigment. Depending on the length of the tail determines how much merle can be expressed or seen in the dogs coat. An enormous amount of studies and trial breedings have led geneticist to understand that there are several different types of merle. They have found 7 alleles of merle and their base pair numbers and 26 combinations of merle; meaning, a merle is not only one of the explanations below, but multiple. They can be m/Mc, Mc/Mc, Mc/Ma ect. A merle can even be a tri-allelic: m/Mc/M (having a major and minor allele)

m- nonmerle/wild type
Mc- cryptic merle 200-230
Mc+ cryptic merle 231-246
Ma- atypical merle 247-254
Ma+- atypical merle 255-264
M- merle 265-268
Mh- herding harlequin 269-280 creates white without piebald/parti gene.

Some labs have now started sequencing merle. Vemodia or Tilia now do.

So, now the question of health. Many mistakenly believe that all merle dogs come or are at risk for health problem. To understand why that is it isn’t true it is important to know how. The gene deletes pigment. If too much pigment is diluted it can indeed affect the eye and ears of that dog. This typically can’t be achieved with a single merle. It takes too merles to run a risk of the allele being long enough to cause problems. However, even with two merle, If the combined length of the merle gene is of a shorter allele sizes between 265 – 269 bp the pups wouldn’t run a chance of defects and have simple “classic” merle coat color patterns. If the merle allele is over 269 bp, then yes. The pups in that litter have a 25% chance of being deaf and blind, which would be extremely irresponsible of the breeder. The risks all come down to the combined length of the merle allele. Shorter alleles, single merle, has no more of a chance than any other dog of having a health issue.

There is more to preserving and protecting the qualities of a breed than color or pattern. If that is all there is to it, then go back to the original solid back and solid white standard that was originally set. But we accept phantom, brindle, and sable when there is absolutely no proof that they were originally around when the breed Standard was set. People were once adamantly hateful toward them at one time. Merle Poodles are accepted by DNA, and AKC.

Responsible merle breeding can produce nice healthy stock.