Labs Offering Merle Testing
Results Offered and What Those Results Mean


Note: Labs on this list who are using the term "cryptic Merle" are not referring to the proper genetic Mc allele on the M locus - 200 - 230 bp

Mc expresses and breeds the same as non-Merle.

These labs are still using the term in a general non-genetic manner which also includes "ghost", "hidden" and "phantom" Merle. In the past these terms have been used to describe a dog who was presumed to be m/m but then bred as a Merle - m/M.

These dogs may not be expressing a Merle pattern for several genetic reasons -
Ay - Clear Sable, e/e - Clear/Recessive Red/Yellow, Mosaicism or a shorter Non-Expressing Merle allele of Mc+ or Ma and occasionally Ma+.

The term cryptic Merle has also been used in the past to describe a "Minimal Merle" pattern which is known to be caused by two different Merle genotypes -
Mh - Harlequin Merle and Mosaicism where the longer original M allele has become the Minor allele.

Again this terminology was used in the past to describe something we had no genetic knowledge of. The newer method of high-resolution testing has given us theses answers.

"Cryptic Merle" now genetically refers to Mc - 200 - 230 bp, an allele on the M Locus that is so shortened/truncated that it can no longer express a Merle pattern..

Mc will express and breed the same as Non-Merle. Mc will not lengthen.

A dog who is m/Mc or Mc/Mc will not breed as M and will not produce offspring who are Merle patterned.

The article I wrote for the Australian Shepherd Club of America covers this in detail.
"Unraveling the Mysteries of Merle" 

The Scale of Merle
The Scale of Merle


Labs offering High-Resolution Testing

Example of Newer High-Resolution Test Result which includes 2 minor alleles due to Mosaicism
Example of Newer High-Resolution Test Result which includes 2 minor alleles due to Mosaicism

Tilia - High-Resolution Testing Method  - Recommended 
Mc, Mc+, Ma, Ma+, M and Mh - base pair numbers provided. 
Mosaic results provided. 
Alleles based on the "langevin et al" paper.
Formerly Vemodia - lab that worked on the Merle paper with me.
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0198536


UC Davis High-Resolution Testing Method - Recommended 
Base pair numbers provided.  States that mosaic results are provided but there have been no examples shared as of yet of a mosaic result. They were sent 2 dogs already tested as mosaics by Tilia and did not report a mosaic result. (it is possible that the cells containing the minor alleles were not present in the sample material tested.)
After some comparison testing with UC Davis using dogs who have already been tested with Tilia the base pairs numbers from UC Davis seem to be a very good comparison to the "langevin et al" scale.
The one unknown at this time is where UC Davis' Mh allele starts - 268 or 269. One dog tested with Tilia as 270bp also tested as 270bp with UC Davis. However breeds like the Frenchie and Aussie who commonly have a 269bp Mh allele have been testing as 268bp. More comparison testing of dogs tested as 269 with Tilia need to be done.


Orivet - High-Resolution Testing Method 
Mc, Mc+, Ma, Ma+, M and Mh - base pair numbers provided.
Mosaic results provided.
Alleles based on the "langevin et al" paper.
After some comparison testing with Orivet using dogs who have already been tested with Tilia the base pairs numbers from Orivet are  3 - 4 bp shorter than the scale I set-up with Tilia for the "langevin et al" paper.
Dogs tested as M are expressing an Mh phenotype and dogs testing on the high side of Ma+ express a typical M pattern. If you do have a result from Orivet it is important to add 3 - 4 bp to the number reported.

Laboklin/Labogen - High-Resolution Testing Method
Mc, Mc+, Ma, Ma+, M and Mh - no base pair numbers provided.
Mosaic results provided.
Suggests that Mc and Ma can lengthen to M 
"Cryptic Merle (Mc) is a short version of the merle allele with very little merling effect if any. Cryptic merle is not associated with health problems but it is a mutable allele and when the dog is bred it may well expand to regular merle in the puppies and so it should be treated same as regular merle and dogs with cryptic merle should only be bred to dogs with no merle." Sa
me information is stated for the Ma allele.

This is of course incorrect - Mc will express and breed the same as Non-Merle. It will not lengthen.
The main reason for not recommending Laboklin is that base pairs are not provided therefore important  information is missing. As well I am not sure what their borders are for reporting the different alleles as they consider their base pair information to be "confidential".


Biofocus - High-Resolution Testing Method 
Mc, Ma and M - no base pair numbers provided. 

No mosaic results provided.
Have stated that they do find mosaic results but the information is not "important enough" to pass along to the customer.
Not Recommended as no base pair numbers or mosaic results are provided.


Slovgen - High-Resolution Testing Method 
Using a revised scale of numbers set out in the "Murphy et al" paper - testing for T (poly-a tail) length.
Mc - cryptic merle - 25-62 T
Ma or Md - atypical or dilution - 63-73 T
M - merle - 74-85 T
Mh - harlequin - 86 and more T

These T numbers can be compared to base pairs by adding 187 to the number provided.
HOWEVER any comparison would have to be done using the "Langevin et al" scale.
Mc going all the way to 249 is much too long. There is a very good chance that a length of 62T (249 bp) will delete pigment to white when combined with M. 249 bp is the Ma allele.
Mc should not go past 43T (230bp) in order to ensure that no pigment is deleted to white when combined with M. Their M allele is starting at 261 bp which is still very much Ma+ and not a typical M allele.
If you do have a result from Slovgen add 187 to the T length to get the base pair numbers and use the "Langevin et al" scale to identify the correct allele. 

Stated on their website - "The dog can be merle mosaic, ie. It can carry several types of merle alleles in its cells. Intergenerationally, it may lead to shortening or expansion of the merle allele. In general, it is not appropriate to mate dogs with merle alleles together because of potential health risks"
This is not correct - Mc has never shown to lengthen to any other allele and is very safe at a length of 43T - 230 bp to breed to M. I have only seen a few results from Slovgen so am not sure if they are providing mosaic results or just mention it on their website.


Genomia High-Resolution Testing Method 
Mc, Md, M and Mh - T length number provided based on "Murphy et al" paper.
(See explanation given above for Slovgen.)
Mosaic results not provided.

Suggests that Merle can lengthen - "The polyT sequence may become shorter or may expand from generation to generation."
The Mc/M genotype (cryptic merle / merle) is also risky for breeding. This genotype exhibits merle pattern and has usually no health problems (but health problems may occur!). Cryptic merle dogs must be bred only to non-merle dogs and when the dog is bred the cryptic allele may well expand to regular merle."

This is not correct.
Mc - Cryptic Merle will breed the same as Non-Merle.
Mc has never been shown to lengthen to anything, let only M.


At this time Tilia and UC Davis are the labs I recommend from this list, as they provide all necessary and  reliable information needed for a breeder and have a full understanding of the workings of Merle. 
NOTE - however as already stated we have not yet seen a mosaic result reported by UC Davis.



Labs using Old Testing Method

Example of an older Merle Test result.
Example of an older Merle Test result.

Embark - Old Testing Method - Recommended 
M* - SINE insertion "yes" or "no"
Offers a very in-depth description of what the results mean and where further testing can be done based on the "langevin et al" paper.
https://embarkvet.com/resources/blog/embark-introduces-merle-coat-color-testing/


GenSol - Old Testing Method - Recommended 
M - SINE insertion "yes" or "no".
Offers an explanation of the lengths of Merle and suggestions further more detailed testing.


Animal Genetics - Old Testing Method  
Mc and M

Using outdated non-genetic information for the meaning of "cryptic merle".
"Many solid dogs are actually cryptic or phantom merles and can produce both Merle and double merles. A cryptic or phantom Merle is a dog which phenotypically appears to be a non-merle or very faint patches of Merle that can go unnoticed. Animals that do not present the Merle phenotype may possess the Merle genotype and subsequently produce Merle offspring. These animals are known as cryptic Merles."

This does not refer to the known genetic Mc - Cryptic Merle allele - note the use of the word "phantom."


Antagene - Old Testing Method
M - SINE insertion "yes" or "no"



Certegen
- Old Testing Method 
 
Mc and M

"Dogs with cryptic merle (also called phantom or ghost merle), typically display little to no merling and some may be misclassified as non-merles."

Using outdated non-genetic information for the meaning of "cryptic merle". 


Labgenvet - Old Testing Method 
Mc and M

"Some dogs may carry the mutated gene, but do not show a typical merle pattern for coat or eye color; these dogs are described as"Cryptic Merle" (Mc/N). The mutation that results in cryptic merle dogs is caused by the insertion of a SINE sequence that is slightly shorter than the SINE sequence found in the typical merle. Since cryptic merle animals have a normal appearance, a DNA test is required to detect the presence of the cryptic merle gene. A cryptic merle dog (Mc/N), if mated with a typical merle dog (M/N), may unfortunately produce double merle dogs (M/Mc), with a high probability of congenital anomalies. It is therefore not possible to rely on the appearance of the animal to judge whether it is safe to mate with a merle dog."

States that Mc is a shorter SINE insertion but that Mc x M will produce "Double Merle" - Mc/M.
Obviously what they are identifying as Mc is much too long.


VetGen - Old Testing Method 

M - SINE insertion "yes" or "no".


Genoscoper/Optimal Selection - Old Testing Method
Mc and M


Feragen - Old Testing Method 
Mc and M

Using outdated non-genetic information for the meaning of "cryptic merle".

"If the dog has a rather short insertion variant, one speaks of cryptic merle or phantom merle (Mc). This gene variant is usually hidden by a dog because no Merle drawing is obvious or only very small inconspicuous areas on the body indicate Merle."

This does not refer to the known genetic Mc - Cryptic Merle allele - note the use of the words "phantom and hidden".

Suggest that Mc can length to M

"Another peculiarity of the merle insertion is the instability of the additional sequence length. So a short Mc variant can become a long Merle variant (M) and vice versa. This is particularly important when mating Merle dogs (M / m) with optical non-Merle dogs (Mc / m or Mc / Mc). In this combination, double-merle offspring may occur if a Mc variant in the next generation changes to the Merle variant (M). Even the genotype M / Mc (Merle / cryptic Merle) can already have health restrictions. Therefore, Mc carriers should only be paired with non-Merle dogs (m / m)."

This is incorrect information based on phenotype not genotype testing - Mc will express and breed the same as Non-Merle. It will not lengthen.


MYDOGDNA -Old Testing Method 
M - SINE insertion "yes" or "no".

"It is now known that there are varying lengths to the insertion, enabling subclassification of different merle alleles. In general, a "cryptic merle allele" (Mc) is a merle insertion shortened to the extent that it is no longer able to cause a coat pattern change even when it is present in the genome of a dog. Therefore, dogs carrying "cryptic merle" show only very slight merle colouration or no merle colouration at all. The cryptic merle allele is currently not known to be associated with health concerns. The merle test included in the MYDOGDNA™ testing service is able to state whether a SILV gene merle-associated insertion is present in the genome of the tested dog, but does currently not report separately on different lengths of the insertion."

They do provide the information that there are different merle alleles and they only test for the presence or absence of the SINE insertion, however there is no understanding of the Mc - Cryptic Merle allele which will never "show only very slight merle colouration." 

"Dogs that carry two copies of (= are homozygous for) the merle (M/M) variant are usually predominantly white. These so called double merle dogs (M/M) are prone to several health concerns, such as deafness, eye development defects and blindness, and may be stillborn. In certain breeds, also heterozygous merle (M/m) dogs may suffer from similar health issues. Mating of two merle is not recommended to avoid the health concerns associated with double merle dogs."

The only known issues from "Double Merle" are vision and/or vision impairments. It does not cause a pup to be "stillborn".
It is not correct that "in certain breed, m/M dogs may suffer similar health issue."
I go over these incorrect ideas in detail on the "Myths and Speculations" page.


EVG - Euro Vet Gene - Old Testing Method

Mc and M

Suggest that Mc can length to M 

"Inheritance of merle is genetically unstable for both M and Mc alleles. In the offspring allele M can occasionally undergo reduction to produce Mc, while Mc may expend and revert to M. When breeding cryptic merle (Mc/m) with a non-merle (m/m) the offspring can have following genotypes: cryptic merle/non merle (Mc/m), merle/non merle (M/m), non merle/non merle (m/m)."

This is incorrect information based on phenotype not genotype testing - Mc will express and breed the same as Non-Merle. It will not lengthen.


Embark and GenSol are the labs I recommend from this list as they have a clear understanding of the genetics of Merle and offer an inexpensive test that can be done along with other color testing to give a breeder a base idea of the Merle status of a breeding dog. This is very helpful with a dog who looks non-Merle in expression.

A result of m/m will mean no further M locus testing is necessary.

A result of M or M* from either lab will indicate further testing should be done with a lab using the High-Resolution testing method.


Diagram explaining in more depth Embark's testing method and what the results indicate.
Diagram explaining in more depth Embark's testing method and what the results indicate.

Paw Print Genetics - Mc, Ma, M and Mh - base pair numbers provided.
Mosaic results provided.

Offers information in regards to the Mc allele expressing with a Minimal Merle pattern.
Mc length bin includes "Langevin et al" Mc and Mc+ alleles.
"In general, dogs with M allele sizes between 200 - 246 base pairs (bp) have been associated with non-merle or minimal-merle coat colors/patterns and are often referred to as "cryptic" merle".

Mc and Mc+ create no merle pattern at all.
Minimal Merle can be caused by 2 different Merle genotypes -
#1 - Mh - Harlequin Merle
#2 - Mosaicism where the longer original M allele has shortened/mutated and has become the "minor" allele with a lesser percentage of cells then the shortened allele.

Example of Minimal Merle due to Mosaicism
Example of Minimal Merle due to Mosaicism
 Note the lower peak of the original M allele
Note the lower peak of the original M allele


Differences between "langevin et al" Mc and Mc+ alleles 

Mc when bred to M does not delete pigment to white.
Mc+ when bred to M does have the ability to delete pigment to white and therefore comes with the risk of hearing and/or vision impairments as the following example demonstrates.

Based on the bin designations by PPG, 240 bp falls into the Mc allele. Mc - 200 - 230 "langevin et al;" will not delete pigment to white when inherited with M.
Based on the bin designations by PPG, 240 bp falls into the Mc allele. Mc - 200 - 230 "langevin et al;" will not delete pigment to white when inherited with M.

Suggests that Mc can lengthen and Mc should not be bred to M due to the chance for "Double Merle" offspring.

Any dog testing as m/Mc that produces Merle pattern offspring will have an M allele, it is a matter of finding it with further investigation.
Mc has not lengthened to M

Ben was tested as m/Mc but produces Merle patterned offspring. I arranged for further testing with Tilia labs using a Germline cell sample (semen) and of course there was a minor M allele. Mc does not lengthen to M.
Ben was tested as m/Mc but produces Merle patterned offspring. I arranged for further testing with Tilia labs using a Germline cell sample (semen) and of course there was a minor M allele. Mc does not lengthen to M.