When did you start researching canine
In 2005, I was collecting genetic data for a
disorder in Shetland sheepdogs called dermatomyositis. I noticed
that the dogs in the study had different coat colors: there were
sables, tri-colors, and blue merles. I decided that I would to try
to use the genetic data to map the gene for merle, and I was
successful! I have worked on merle and related patterns ever since.
What is the ultimate intent of this research?
The goal of the harlequin research is to identify
the gene that causes the coat pattern.
When did you identify the harlequin gene? And
how did you realize the gene was present also in the Collie breed?
After I identified the gene causing merle, I read a
journal article from the 1980’s describing the harlequin pattern
found in Great Danes. I knew immediately that I wanted to try to map
that gene, too. I did not become aware of harlequin dogs in other
breeds until 2009, when I received an email about a unique collie in
Finland. Even though the coat pattern looked just harlequin in Great
Danes, I was not convinced that it was a form of harlequin until I
was able to show that the collie was not a double merle.
All right, but what is the harlequin gene?
In Great Danes, harlequin is caused by a mutation
in a gene that functions in the breakdown of proteins that are no
longer needed by the body.
Can you explain how the harlequin gene works?
The harlequin gene modifies the merle coat. While a
blue merle dog has black spots on a grey background, a dog with
merle AND harlequin will have black spots on a white background. The
harlequin gene erases the dilute background. The harlequin gene does
nothing to the coat of a dog that is not merle.
And how is it transmitted?
The harlequin gene is dominant. In dogs with a
merle coat, one copy of the harlequin gene will make the background
white. That means that it only takes one parent with harlequin to
have a litter with harlequin puppies. In Great Danes, puppies that
inherit two copies of the harlequin mutation die soon after
Have you any idea how the harlequin gene came in
The harlequin gene was not brought into collies by
another breed. Collies do not have a mutation in the same gene as
Great Danes. New gene mutations that are naturally acquired are most
likely the cause of harlequin dogs in other breeds. This new
mutation may have been in the breed for awhile, but only became
apparent when it occurred in a merle dog. There is no way to detect
the mutation in a non-merle collie.
What is the spread of this gene? How many
countries has been found so far?
We have identified harlequin collies in America,
Finland, Denmark, and The Netherlands. These collies probably do not
all have the same mutation. Most likely, a new mutation occurred
independently in each of these lines.
Can you explain why harlequin, as well as merle,
is not a color?
Harlequin and merle do not determine the color of
the coat. They cause a pattern of varying intensities (from full
pigmentation to no pigmentation) of the base color, which is
determined by other genes.
Do you think this research is useful for men,
The gene that causes harlequin in Great Danes is
critical for normal protein breakdown. Our findings shed new light
on important sequences within the gene, and the discovery of
additional harlequin genes could identify other genes important in
Well, Dr. Clark, we thank you very much, and we hope
to get the best from your work!