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 

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


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.


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." Same information is stated for the Ma allele.

This is incorrect - Mc will express and breed the same as Non-Merle. It will not lengthen.


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.


At this time Tilia is the only lab I recommend from this list as they provide all necessary information needed for a breeder.
I have only seen a few example test results from Orivet and their base pairs numbers seem to be 4 - 5 shorter then 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.
I have provided Orivet with 5 examples already tested through Tilia so they they can compare their base pair numbers.


Labs using Old Testing Method

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

Embark - Old Testing Method 

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.


GenSol - Old Testing Method
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.


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


UC Davis - Old Testing Method
Mc and M

Using outdated non-genetic information for the meaning of "cryptic merle" and suggests that Mc can lengthen to 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. Inheritance of merle is genetically unstable and Mc may undergo expansion and revert to M."

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

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


Certegen - Old Testing Method
 Mc and M
Using outdated non-genetic information for the meaning of "cryptic merle".
"Dogs with cryptic merle (also called phantom or ghost merle), typically display little to no merling and some may be misclassified as non-merles."


Labgenvet - Old Testing Method
Mc and M

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.

"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."


Genomia
Mc, Md, M and Mh - T length number provided based on "Murphy et al" paper.

Poly-T not Poly-A is measured which is not as precise in measurement. 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."


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

Very incorrect information provided -

"This SINE advertisement is genetically unstable due to its retrotransposomal origin. In the study (Sponenberg, 1984), a case was reported where, when joining individuals M / M and m / mu 3-4%, the progeny do not have a merle allele. This phenomenon is called germ cell reverse (reverse mutation) from M to m. Reverse mutation occurs not only in germ cells but also in somatic cells. Therefore, this pattern on the hair alternates with cells with normal pigment synthesis."

Any length of M SINE insertion cannot "disappear" and become "m" - non-Merle.
The 1984 study would have been seeing mosaic M/M dogs - example [Ma]/M/M - passing along a shorter minor non-expressing allele to offspring making that offspring appear to be "non-Merle" much like the following example. Bahama - [Ma]/M/M - one offspring has inherited her minor Ma allele which is Non-Expressing.



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.



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.

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 incorrect 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.