Australian Shepherd Journal Review

The following is a review of the Merle book printed in the  "Australian Shepherd Journal" Sept/Oct 2019 issue.

By: Tracy Libby, Reviews Editor

Merle-SINE Insertion from Mc-Mh - The Incredible Story of Merle

Have you heard about the Incredible Story of Merle? No? Well, you're going to want to order a hard - or digital copy of Mary Langevin's book,
Merle-SINE Insertion from Mc-Mh - The Incredible Story of Merle (2019).

Sure, it might sound like a special on the Hallmark movie channel, but it is a fascinating look at a very complicated genetic topic, which should be of great interest to Aussie owners-especially breeders.

Langevin, who has been breeding Catahoulas for 23 years, simplifies an amazingly complicated topic with plenty of easy to understand analogies, text, graphs, diagrams, charts, and hundreds of corresponding color photographs.

That said, don't be fooled into thinking this book is oversimplified. Langevin takes an in-depth look at the history behind the findings and discovery of "Merle's many phenotypes"-starting with Dr. LA Clark's identification of the Merle SINE insertion (Short Interspersed Element) in 2006, and how in 2009 testing came to a standstill, as many thought the results were flawed. After all, how could a solid dog expressing no merle pattern test as M/M?

"We now understand that these dogs were most likely Mc / Mc, having two cryptic merle mutations-a length of Merle so shortened or truncated that it can no longer cause a change to the coat pattern," writes Langevin.

How far we have come in a relatively short period of time, eh?

You'll learn about data collecting methods, such as fluorescent fragmentation analysis, and processing techniques, such as polymerase chain reaction (PCR)-a procedure that amplifies (expands) a small segment of DNA into thousands or millions of copies with the identical sequence so that the sample can be studied in more detail.

Langevin explores the intricacies of the merle pattern from 27 merle phenotype combinations to double merles (including vision and hearing impairment, unexplained white patterns, lethal white, and myths and speculations) to cryptic merles (cryptic merle versus minimal merle versus hidden merle).

You'll read about the how's and why's of seven alleles on the M locus, and, equally important understand,
1) which combinations of alleles can express with a merle pattern

2) how crisp and clear will that pattern be, and

3) which combination of alleles can delete pigment to white within the merle pattern.

"These are important distinctions for a breeder who strives to produce Merle patterns that fall within the given guidelines of many breed standards," writes Langevin. You'll read and see photographs of the most typical merle phenotypes for 27 different allele combinations.
(There are 28 possible combinations from seven alleles. However, Langevin, as of publication, notes there were no photographs of Ma+/Mh.)

Langevin shows you color photographs of Mc, Mc+, Ma, and Ma+ in their heterozygous and homozygous states. For example, you will see photographs of Chance, an Australian Shepherd sire (Mc/Mc -223/223, DD/SS) and Autumn, an Australian Shepherd dam (M/Mh - m/269, D/d, S/S) and their offspring. You'll see that the dam and offspring have the same length of Mh -269, and you will see their phenotype expression. It's like looking into a crystal ball.

"Breeders need to know the most typical phenotype expression for a given combination; how that dog will breed, what patterned offspring this dog can produce," writes Langevin. "These are the biggest questions and the alleles of Mc, Mc+, Ma, Ma+, M and Mh, provide these answers."

The book further explains mosaicism, undetected mosaicism, somatic and germline cells, major and minor alleles, shortening and lengthening of a merle allele, and so much more! Thankfully, she also clears up some misconceptions and myths surrounding terminology including double merle and lethal white.

If you're thinking you need a course in cellular or molecular biology to understand the intricacies of the merle gene-think again. Langevin does an excellent job of simultaneously unraveling the mysteries of the merle gene and connecting the dots yet not delving too deeply into the scientific mumbo-jumbo that oftentimes causes our eyes to glaze over. 
"I am not a geneticist," writes Langevin, "nor do I have any degrees in the field of biology or any of the sciences for that matter. My mission is to make the information contained in this book accessible and understandable for everyone, within every breed who has an investment in the Merle trait."

The book covers a wide array of breeds, and I'm certain you will be fascinated by the myriad photographs of Australian Shepherds, as well as breeding charts and corresponding color photographs illustrating examples of the offspring's phenotypes.

The one teensy issue I have with the book is the labeling of toy and miniature Australian Shepherds. As staunch supporters of the breed we recognize there are no miniature/ toy Australian Shepherds. Granted, in the grand scheme, it's a minute detail as well as a pet peeve of mine, but it certainly does not detract from the excellent information contained in the book.

I highly recommend this book, which should be at the fingertips of Aussie breeders and advocates alike. You can order this book on Langevin's website:

While you're there, test your knowledge with her quiz on Merle.
The average score from 423 respondents is 41.2 percent. How well can you do?

There's also a closed Facebook group available at