|
The Genetics
of Coat Color in the White (German/Swiss) Shepherd Dog
©
By Michael Handley
1906 German newspaper photograph
of a young White Shepherd Bitch
© Ari Valkhoff/ Ruut Tilstra
Abstract
One of the most quoted books on dog genetics and coat color
is "The Inheritance of Coat Color in Dogs" by
Clarence C. Little, first published by Comstock in 1957.
Little's genetic research was based on hypothesized alleles
(variation of DNA coding for a particular gene locus, or
chromosomal location) with hypothesized dominance at
hypothesized gene loci (plural of locus) to fit data
obtained by observing and categorizing coat colors and color
patterns appearing in various dogs breeds and litters.
Modern genetic research now reveals that for some observed
traits, or phenotypes, like coat color, the actual genetics
are different from those hypothesized by Little and others.
Little (1957) hypothesized that dilution or partial albinism
genotypes of the C gene caused the cream and white coat
color variants in domestic dogs. Little's hypothesized
partial albinism explanation for cream and white colored
coats has been applied across most domestic dog breeds,
including white coat dogs from German Shepherd breed lines,
since Little first published his book.
Comparative analysis of the dog genome and specific breed
DNA sequences now shows that Little's hypothesized gene (C)
color dilution explanation for cream and white colored coats
is most likely not a relevant determinant of cream and white
coats known to commonly occur in many dog breeds. Little's
1957-era partial albinism dilution explanation, as applied
to explain domestic dog white and cream coat colors, can be
replaced by the findings of modern genetic research.
Genetic research has, at least partially, identified the
actual genetic hair color regulation mechanism behind white
and cream colored coats in several breeds of the domestic
dog. Research has shown that a recessive ‘e’
allele at the Extension (E) gene is at least partially
responsible for cream and white coat color. The (E) gene,
now identified as the Melanocortin-1 Receptor (MC1R) gene,
is one of the two genes known to code for alleles that are
absolutely fundamental to the formation of all German
Shepherd Dog colored coat variations. When the ‘e’
allele is inherited from each breeding pair parent, the
e/e genotype offspring of certain breeds,
including white coat dogs from German Shepherd breed lines,
always have cream or white colored coats.
A genetic scientist researching the genetic coding of cream
and white colored coats concludes in a related research
paper that, "Because cream [and white] dogs always have an
e/e genotype at MC1R, DNA testing for an ‘e’
allele should be predictive that the dog is heterozygous for
cream [and white] coat color in breeds such as Akita,
Caucasian Mountain Dogs, German Shepherd Dogs, Miniature
Schnauzers, and Puli." Breeders of standard color only
German Shepherd Dogs and White German Shepherd Dogs#
may wish to test their breeding pairs for the ‘e’
allele to better refine their respective breeding programs
as to coat color.
# -
White Shepherd and Berger Blanc Suisse (White Swiss Shepherd)
breed lines were established from White German Shepherd Dog
breed lines during the last quarter of the twentieth century,
and therefore, would be expected to carry the e/e genotype.
See Wikipedia Encyclopedia for "White
Swiss Shepherd"
We are grateful to Dr. Sheila M.
Schmutz, Ph.D., Professor, Department of Animal and Poultry
Science, College of Agriculture and Bioresources at the
University of Saskatchewan for her research on the genetics
of coat color in the domestic dog. Several research papers
of Dr. Schmutz and her colleagues serve as source material
to this discussion of the genetic functions behind white and
cream coat color in German Shepherd Dog breed lines. We also
thank Dr. Schmutz as well as Ruut Tilstra with the
International White Shepherd Federation, and Judy Huston and
Joanne Chanyi with the White Shepherd Genetics Project for
their review comments on this article.
Contents
The Genetics of Coat Color in the White
(German/Swiss) Shepherd Dog
Acknowledgements
Fundamentals of Hair
Pigmentation
Colored Coats in the German Shepherd
Dog Breed
Genetic Research for the Explanation
of White Coats
A Gene Fundamental to Colored Coats Also
Codes for White Coats
White (German/Swiss) Shepherds Carry
DNA for Colored Coats
DNA Tests To Detect "White Factored"
Colored German Shepherds
MC1R e/e Genotype Research
Conclusion
References
Bibliography
Mammalian hair is composed of a strong structural protein
called keratin, the same kind of protein that makes up the
nails and the outer layer of skin. Hair grows up from hair
follicles, which house a group of highly active cells that
form pigment and keratin for each hair fiber. A biological
pigmenting polymer called melanin forms the coloring agents
that are injected into hair fibers.
The word melanin is derived from the Greek word for black,
and generally refers to two known melanin pigment variations
named eumelanin and phaeomelanin. Eumelanin is a brown/black
pigmenting polymer and phaeomelanin is a yellow/red
pigmenting polymer.
As each hair fiber is constructed in the follicle, eumelanin
and phaeomelanin pigments are injected in various
formulations and densities of color granules by little
pigment factory cells called melanocytes that are co-located
with keratinizing cells at the base of each hair follicle.
Color granules are keratinized along with the cytoplasm of
each hair fiber as it grows from the lower follicle
structure before it emerges from the skin layer. Dogs have a
variety of genes consisting of many gene loci and alleles
located across several chromosomes that regulate where, how
and if each hair follicle melanocyte injects eumelanin and
phaeomelanin color granules into its growing hair fiber.
These genes and alleles are observed to vary from breed to
breed.
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To go deeper
into the modern understanding of the genetics of
dog coat color it is necessary to understand
some terminology: All dogs have 78 chromosomes,
39 from each parent forming 39 chromosome pairs.
Each chromosome pair lines up specific gene
pairs, (one from mother and one from father) at
a specific location on the chromosome identified
as the locus for that gene. (Loci is the
plural.) Often a particular gene at a particular
locus has two or more variations in the DNA
coding they carry. Each variation of that
particular gene is called an allele of that
gene. Some alleles are dominant and some are
recessive where the dominant allele always
dictates the action of the gene pair. Recessive
alleles can express themselves only when two
copies of the recessive allele (one each from
mother and father) appear in a gene pair. Some
alleles are somewhere in between dominant and
recessive and are called incomplete dominants or
co-dominants. This means that the trait is seen
with just one co-dominant allele copy, but in
genotypes that include combinations of
co-dominant allele pairs, the phenotype, or
resulting physical characteristics, can vary
according to the pairing combination. An
inherited gene pair trait, half from the mother
and half from the father, is called the genotype
in the offspring. Two animals whose genes at a
particular locus differ by even a single allele
are said to have different genotypes. Dominant
alleles are denoted by capital letters and
recessive alleles are denoted by small letters,
for example, E is dominant e is
recessive and Em is
co-dominant with E. |
The interaction between genes that code for melanin pigment
production and genes that regulate the variation, ratio and
palette of melanin pigment injected into each hair fiber by
melanocyte cells is the genetic mechanism that determines
coat color and coat coloring patterns in mammals. Various
alleles of one or more gene(s) regulate eumelanin (brown/black)
pigment production and various alleles of another gene (or
genes) regulate phaeomelanin (yellow/red) pigment production
in hair follicle melanocytes. Various alleles of yet
different genes regulate the density, distribution pattern
and exact color palette of eumelanin (brown/black) and
phaeomelanin (yellow/red) pigment granules that melanocytes
inject into growing hair fiber.
The interaction of different combinations of alleles from
multiple gene loci act together on melanocytes to vary
pigment granule formation, density and distribution in each
hair fiber. The dark eumelanin pigment granules injected
into hair fibers may appear as black or be modified to a
chocolate brown and the lighter phaeomelanin pigment
granules may be modified from yellow to tan, light brown,
red/rust, or cream. In addition to pigment granule
formulation the density of pigment granules injected into
each hair fiber can also moderate hair color. For example: a
low density of pigment granules may result in lighter hair
colors, higher densities can result in darker hair colors,
and pigment granules that clump together, rather than
distribute more evenly, can give hair fibers a blue color
hue.
Agouti (A) alleles and MC1R (E) alleles each create
chemicals that compete with each other to regulate pigment
function in hair follicle melanocytes:
-
alleles of the Melanocortin-1 receptor (MC1R) gene code
for variations of Melanocyte Stimulating Hormone (MSH)
which regulate eumelanin (brown/black) pigment
production in hair melanocytes, and
-
alleles of the Agouti (A) gene code for variations of
Agouti Signal Peptides (ASIP) which regulate the density,
distribution pattern and exact color palette of
eumelanin (brown/black) and phaeomelanin (yellow/red)
pigment that melanocytes then inject into hair fiber.
The regulatory competition between each variation of ASIP
and MSH is the mechanism that forms German Shepherd coat
colorations ranging from the classic German Shepherd sable
coat colors all the way to a solid black coat color.
The MC1R gene, historically called the Extension (E) gene,
even has an allele that codes for a version of MSH that does
not switch on the eumelanin pigmenting processes within hair
follicle melanocytes, thus leaving no eumelanin for the
Agouti (A) gene alleles to regulate. Another gene, as yet
undiscovered by genetic researchers, is thought to regulate
phaeomelanin (yellow/red) pigment production in a manner
similar to the MC1R eumelanin regulating function. Alleles
of yet another gene, or genes, such as the Melanophilin (MLPH)
“pigment clumping” gene*, can further vary
function in melanocytes to modify color.9Genetic
science has not yet identified, through genetic testing, all
of the genes and alleles responsible for the regulation for
coat hair color.
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* - Function
of the Melanophilin (MLPH) “pigment clumping”
gene has historically been attributed to the
Dilution (D) gene. The blue coat phenotype (also
sometimes described as charcoal grey) is often
described as a “dilution” or “paling” of the
black coat color. This so-called “dilution
factor” has historically been mapped to gene (D)
and is known to cause the clumping of pigment
granules in hair fibers. Genetic research has
recently shown that the blue coat pigment
clumping condition is caused by an allele
mutation of the Melanophilin (MLPH) gene.9
In the German Shepherd Dog this gene acts in
combination with Agouti (A) and MC1R (E) alleles
to form the blue coat color. |
The Wild Type Black Banded Hair aw
Agouti allele, when coded at the Agouti (A) gene, regulates
the density, distribution pattern and exact color palette of
eumelanin (brown/black) and phaeomelanin (yellow/red) hair
pigmenting in many wild animals. The aw
allele causes melanocytes to vary the formulations and
densities of eumelanin (black/brown) and phaeomelanin (red/yellow)
pigment granules they inject into each hair during hair
fiber production. The unique aw
allele coat pattern is distinguished by hair fibers that are
banded black at the tip end, changing to a reddish or cream
coloration along the mid-section and finally changing back
to black near the skin. Over different parts of the body
this can impart a color banding appearance along the full
length of some hair fibers and near solid color along the
full length of other hair fibers.
Alleles of the Agouti (A) gene, which is one of the major
coat color determinate genes for the German Shepherd Dog
breed, affect not just where, but also whether the eumelanin
(brown/black) phaeomelanin (yellow/red) shift occurs hair by
hair over an animal’s body. The primary Agouti regulated
coat color patterns of the German Shepherd breed are
typically categorized as sable, black and tan and
solid black, however, these color patterns can vary
greatly in color intensity and pattern detail among
different breeding lines. The variation of intensity and
detail occurs because the expression of alleles at certain
gene loci can modify the expression of alleles at other gene
loci.
The aw allele is thought to code
for the German Shepherd sable (or wolf) coat
color pattern, the at allele is
thought to code for the black and tan coat color
pattern and the a allele is thought to code
for the solid black coat color7, 8.
Several different Agouti genotypes are possible including:
aw/aw,
at/at, aw/at,
aw/a, at/a,
and a/a, where only the
recessive a/a genotype can form
a solid black coat. The dominance order has not yet
been conclusively confirmed through genetic research, but
aw is thought to be dominant over
at with the a allele
recessive to both aw and at.
Genetic research has not yet determined with certainty what,
if any, other Agouti alleles code for German Shepherd Dog
color variations.
White coat hair appears when one or more regulator genes
cause hair follicle melanocytes to inject no melanin pigment
granules into the hair fiber as it is formed in the follicle
structure. One of the most quoted books on dog genetics and
coat color is "The Inheritance of Coat Color in Dogs"
by Clarence C. Little, first published by Comstock in 1957.
Several editions of Little's book have been published in the
intervening years and most other books that discuss dog
genetics and coat color are based on Little's work. Little's
genetic research is based on hypothesized alleles with
hypothesized dominance at hypothesized gene loci to fit data
obtained by observing and categorizing coat colors and color
patterns appearing in various dogs breeds and litters.
Little's work continues to serve as the foundation of
understanding for the determinants of coat color, but
genetic science is starting to show where Little was right
and where he was wrong. Modern genetic research now reveals
that for some observed traits, or phenotypes, like coat
color, the actual genetics are different from those
hypothesized by Little and others.
Little (1957) hypothesized that dilution or partial albinism
ce, ca and
cch alleles of the so called (C)
gene caused the cream and white coat color variants in
domestic dogs. Locus (C), commonly referred to as the albino
and paling gene, was historically used to explain the cream
and white coat color variants of many species. For dogs,
Little hypothesized that a possible cch
(chinchilla) allele of the (C) gene pales phaeomelanin to
cream, that a second possible allele ce
dilutes phaeomelanin to white and a third possible allele
ca causes pure albinism in homozygotes.
Little's 1957 hypothesized explanation for cream and white
colored coats has been applied across many domestic dog
breeds, including white coat dogs from German Shepherd breed
lines.
Most genetic researchers now map the so-called (C) gene to
the tyrosinase (TYR) gene because albinism has been found to
be the result of various genotype mutations at this locus in
mice, humans, rabbits, cattle, and cats. The TYR locus is
known to encode for tyrosinase, an enzyme that ultimately
leads to the formation of the two natural melanin pigments
eumelanin and phaeomelanin within melanocyte cell membranes.
The most frequent form of albinism results from genotype
mutations at the TYR locus that cause the tyrosinase enzyme
to malfunction such that eumelanin and phaeomelanin
production is retarded to varying degrees or fully
eliminated. Over 100 different mutations within the
tyrosinase gene are now known to cause the most frequent
form of albinism genetically labeled as
oculocutaneous albinism type 1, or OCA1.2
The specific mutations that encode for pink-eyed albinism in
the domestic dog have not yet been identified through
genetic testing.
|
A research project
at the University of Saskatchewan Genetic Research
Laboratory has, at least partially, identified the
actual genetic mechanisms behind white and cream
colored coats in several breeds of domestic dog,
including white coat dogs from German Shepherd breed
lines. This research laboratory also searched for
and has not found tyrosinase malfunction in white
coat dogs common to those breeds. Little's 1957-era
tyrosinase malfunction dilution or partial albinism
explanation of the C locus ce,
ca and cch alleles,
as applied to explain domestic dog white and cream
coat colors, therefore, can be replaced by the
findings of modern genetic research. |
 The
Melanocortin-1 receptor (MC1R) gene, more commonly known as
the Extension (E) gene, regulates the production of
eumelanin (brown/black) pigment in hair follicle melanocytes.
Standard color German Shepherd Dog breeders have long
understood the importance of the (E) gene in the formation
of the breed’s distinctive coloration. This gene was
originally identified as the Extension (E) gene because it
was thought the dominant E allele of this gene
"extends" eumelanin (brown/black) pigmentation over the
entire body. An additional allele Em
at the MC1R (E) locus was historically thought to modify
pigment production over the face area to create the "melanistic"
eumelanin black face mask color pattern common in many
breeds, including the standard color German Shepherd Dog
breed.
An additional recessive e allele was also long
thought to exist at the MC1R (E) gene locus, but most German
Shepherd Dog experts traditionally focus attention only on
the dominant E and Em
alleles while giving little notice to the recessive e
allele.* The e/e genotype was not
considered important to German Shepherd breed conformation.
|
In dogs
carrying a genotype that includes at least one
of the dominant E or Em alleles (i.e.
genotypes of E/e or Em/e also see
table below) eumelanin production is not
inhibited and eumelanin pigment is produced per
the dominant allele’s signature trait. In dogs
carrying a genotype that includes combinations
of the dominant E or Em alleles (i.e.
genotypes of E/E, E/Em and Em/Em)
eumelanin pigment production varies according to
the signature traits of the dominant allele
pairings. The "melanistic" face mask will appear
when a dog has either the E/Em or Em/Em
genotype. |
Recent DNA research has verified function of the recessive
e allele at MC1R in several domestic dog
breeds, including white coat dogs from German Shepherd breed
lines. It is known the e allele at MC1R does
not signal hair follicle melanocytes to "switch on"
eumelanin production, as do the dominant E and
Em alleles. Therefore, in
dogs carrying an e/e genotype, there is no eumelanin
available for the Agouti (A) gene aw, at
and a alleles to regulate, and no eumelanin (brown/black)
pigment to inject into the growing strands of hair.
When an e allele at MC1R is inherited from
each parent, the e/e genotype offspring can
have only phaeomelanin (yellow/red) based coat colors of
yellow, tan, light brown, red/rust or cream.
Furthermore, genetic research at the University of
Saskatchewan has recently demonstrated that e/e
genotype offspring, in some breeds, always inherit a cream
to white coat color. Apparently, the phaeomelanin (yellow/red)
hair follicle pigmenting processes in these dogs are
strongly regulated to form cream colors, or are not "switched
on" at all to form white coats. Researchers believe,
therefore, that an as yet undiscovered allele or alleles of
one or more other gene(s) must regulate phaeomelanin (yellow/red)
pigment production in hair follicle melanocytes in a manner
similar to the MC1R eumelanin regulating function.*
White coat dogs apparently have neither hair follicle
phaeomelanin nor eumelanin for the Agouti (A) gene aw,
at and a alleles to
regulate, and no eumelanin (brown/black) or phaeomelanin (yellow/red)
pigment to inject into the growing strands of hair.
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* - Positive
identification of the specific allele, or
alleles, that regulate phaeomelanin (yellow/red)
pigment production in hair follicle melanocytes
will complete our full understanding of the
genetic mechanisms responsible for the formation
of cream to white coat color. We must wait for
additional genetic research for this answer. |
The MC1R recessive e allele has been found in
several dog breeds1, 3: Afghan, Akita*, American
Eskimo Dog***, Australian Cattle Dog, Australian Shepherd,
Beagle, Border Collie, Brittany Spaniel, Cardigan Welsh
Corgi*, Caucasian Mountain Dog*, Chinese Shar-Pei*, Chow
Chow, Cocker Spaniel, Dachshund, Dalmatian, Doberman
Pinscher, English Cocker Spaniel, English Setter, English
Springer Spaniel, Field Spaniel, Flat-Coated Retriever,
Foxhound, French Bulldog, German Longhaired Pointer, German
Shepherd Dog*, German Shorthaired Pointer, German Wirehaired
Pointer, Golden/Yellow Labrador Retriever**, Great
Pyrenees*, Irish Setter, Lowchen, Miniature Schnauzer*,
Pointer, Pomeranian, Poodle*, Pudelpointer, Puli*, Samoyed***,
West Highland White Terrier***.
|
* - e/e
genotype breed that always presented cream to
white coat color in DNA research at University
of Saskatchewan. ** - e/e genotype breed
tested at University of Saskatchewan where some
dogs presented cream color coats and other dogs
presented yellow color coats. *** - e/e
genotype breed tested at University of
Saskatchewan where white is the only standard
breed color1. |
It should be noted that the cream to white coat animals
shown to carry the MC1R e/e genotype
predominately have dark eyes and black skin on the nose,
eyes and paws. It can then be inferred that yet another gene
likely regulates pigmentation of these other structures.
DNA research at the University of Saskatchewan has shown
that dogs carrying cream to white colored coats from several
breeds, including white coat dogs from German Shepherd breed
lines, always have an e/e genotype at MC1R.
The Agouti (A) gene aw, at
and a alleles, that e/e genotype
white coat German Shepherd Dogs#
continue to carry, are hidden, or masked. The alleles are
hidden because neither phaeomelanin nor eumelanin is made in
the hair follicles giving Agouti (A) gene aw,
at and a alleles
nothing to regulate, and no eumelanin (brown/black) and
phaeomelanin (yellow/red) pigment to inject into the growing
strands of hair.
The successive white to white breeding programs that
formally established the White Shepherd and White Swiss
Shepherd breed(s) have "fixed"+ the
e allele (and e/e genotype) at the
MC1R gene locus, but the Agouti color coat alleles remain
hidden in the DNA. Only a potential for the "melanistic"
eumelanin black face mask color pattern has been eliminated
from fixed e/e genotype White (Swiss) Shepherd
and White German Shepherd breed lines. However, a single
pairing of a White (German/Swiss) Shepherd dam of genotype
e/e - aw/aw
with, for example, a Em/Em
- aw/aw
genotype standard color German Shepherd Dog will produce a
litter of Em/e -
aw/aw full sable
colored German Shepherd puppies with "melanistic" eumelanin
black face mask that would be competitive in the prestigious
AKC Westminster Kennel Club dog show. A simple breed type
DNA test on a White (German/Swiss) Shepherd (Berger Blanc
Suisse) dog would return “German Shepherd Dog” as the
probable breed type because the dog carries Agouti (A) gene
aw, at or
a alleles.
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# -
White Shepherd and Berger Blanc Suisse (White
Swiss Shepherd) breed lines were established
from White German Shepherd Dog breed lines
during the last quarter of the twentieth century
and, therefore, would be expected to carry the
e/e genotype as well as the complement of hidden
Agouti (A) gene alleles. See Wikipedia
Encyclopedia for "White
Swiss Shepherd."
+ - An
allele for which all members of the population
are homozygous, so that no other alleles for
this locus exist in the population.
|
This table shows the combination of displayed and hidden
white/cream and AKC breed standard colors that are possible
in the various e genotypes of the German
Shepherd Dog.
MC1R (E)
Genotype |
Agouti (A)
Genotype |
Coat Color and
Pattern Displayed |
Hidden Color
and Pattern Breeding Potential |
|
Em/e |
ax/ax |
sable or
black-and-tan w/mask |
white, lack of
mask |
|
Em/e |
ax/a |
sable or
black-and-tan w/mask |
white & solid
black, lack of mask |
|
Em/e |
a/a |
solid black (mask
not seen) |
white, lack of
mask |
|
E/e |
ax/ax |
sable or
black-and-tan |
white |
|
E/e |
ax/a |
sable or
black-and-tan |
white & solid
black |
|
E/e |
a/a |
solid black |
white |
|
e/e |
ax/ax |
white |
sable &
black-and-tan |
|
e/e |
ax/a |
white |
sable,
black-and-tan & solid black |
|
e/e |
a/a |
white |
solid black |
note:
ax - denotes the
Agouti (A) gene alleles aw
for sable and at
for black-and-tan
a - denotes the Agouti (A)
gene allele for solid black
E - denotes MC1R (E) gene
dominant allele for eumelanin extension
Em - denotes the
MC1R (E) gene allele for eumelanin extension
and face mask pattern
e - denotes the recessive
allele for eumelanin off.
Alleles of the
Agouti (A) gene were genetically identified
through a collaborative research project between
the laboratories of Dr. Greg Barsh at Stanford
University and the Dr. Sheila Schmutz at the
University of Saskatchewan. Unfortunately,
commercial DNA test commonly available as of
Fall 2007 can not differentiate between the
Agouti aw and at
(and other possible Agouti) alleles, so DNA
tests for German Shepherd Dog color may return
only an ax indicator to
signify only that one of the Agouti (A) gene
color pattern alleles is present. Researchers
have, however, identified a nucleotide mapped to
the recessive a allele at the Agouti (A)
gene that signals for a uniform solid black
coat.5, 6 |
One of the conclusions drawn in the University of
Saskatchewan MC1R e/e genotype research paper
may be of particular interest to breeders of standard color
only German Shepherd Dogs and White German Shepherd Dogs.
This conclusion reads, "Because cream [white] dogs always
have an e/e genotype at MC1R, DNA testing for
an e allele should be predictive that the dog
is heterozygous for cream [white] coat color in breeds such
as Akita, Caucasian Mountain Dogs, German Shepherd Dogs,
Miniature Schnauzers, and Puli."
Standard color only German Shepherd Dog breeders may wish to
test their breeding pairs for the e allele to
better refine their respective breeding programs. White
German Shepherd Dog breeders who prefer to occasionally
include "white factored" colored German Shepherds in their
breeding program, may wish to determine if the colored dog
breeding candidates are, in fact, heterozygous for white
coat color before using them in their breeding program. (HealthGene
Molecular Diagnostic and Research Center offers
German Shepherd Dog e allele DNA testing that is
based in part on the University of Saskatchewan research.)
MC1R
e/e Genotype Research
Findings of the white coat MC1R e/e genotype
research project at the University of Saskatchewan Genetics
Laboratory was published in the July/August 2007 (Volume 98,
Number 5) issue of the Journal of Heredity under the title
of "The
Genetics of Cream Coat Color in Dogs" This research
paper also discusses test findings that Little's
hypothesized ce, ca
and cch (chinchilla) alleles of the
albino TYR (C) locus are likely not relevant determinants of
cream to white coats known to commonly occur in domestic dog
breed.
 Other
recent genetic research has shown that other species,
including the white “Kermode” black bear found in the rain
forests along the north coast of British Columbia, also
carry the recessive e/e allele at MC1R. These
white coat bears have cream to white coats dark eyes and
black skin on the nose, eyes and paws. The recessive
e/e genotype at MC1R
research paper on the white-phased “Kermode” black bear4
was published in the September 18, 2001 (Volume 11, Issue
18) issue of Current Biology.
The
recessive gene for white coat hair was cast in the breed
gene pool by the late 19th and early 20th century breeding
program that developed and expanded the German Shepherd Dog
breed in Germany. It is a historical fact that a white
herding dog named Greif von Sparwasser (whelped in
Friedrich Sparwasser's Frankfort kennel in 1879) was the
Grandfather of Horand von Grafrath, (whelped in Friedrich
Sparwasser's Frankfort kennel in January 1895 as Hektor von
Sparwasser) the dog acknowledged as the foundation of
all contemporary German Shepherd Dog bloodlines.* “Der
Deutsche Schaferhund In Wort Und Bild" ("The German Shepherd
Dog in Words and Picture") written by the recognized father
of the breed, Rittmeister (Cavalry Captain) Max von
Stephanitz, in 1921 included a photo of Berno von der
Seewiese, a White German Shepherd directly descended
from Horand. (Photo left of Berno von der Seewiese b.1913
in the kennel of G. Uebe von Seehausen)
Information
provided in early books on the German Shepherd Dog, such as
"The Alsatian WoIf Dog" written by George Horowitz in 1923,
as well as "The German Shepherd, Its History, Development
and Genetics" written by M. B. Willis in 1977, make mention
of Greif and other white German herding dogs, with upright
ears and a general body description that resembles modern
German Shepherd Dogs, having been shown in Europe as early
as 1882. (Photo right is a young bitch from a 1906 German
newsletter publication, author unknown - photo provided by
Ruut Tilstra of the
International White Shepherd Federation10.)
The early
20th century German Shepherd breeding program extensively
line bred and inbred color coat dogs that carried Greiff's
recessive gene for white coats, to refine and expand the
population of early German Shepherd Dogs. Horand’s litter
brother Luchs was also widely bred in the same way in the
expansion of the modern German Shepherd breed. In the first
15 years of pedigreed German Shepherd Dog breeding more than
half the registered dogs had litters with white puppies.
Many of Horand's and Luchs’ progeny produced white pups,
including Berno von der Seewiese (b.1913) who can be found
in the SV breed book.
Our more
complete understanding of MC1R gene function, perhaps, gives
new insight into how the white coat so easily became
established in the early population of German Shepherds and
why Greif’s genes were essential to the development of the
German Shepherd breed. As do White Shepherds of today,
Greif very probably carried Agouti gene alleles, in addition
to other gene alleles for conformation features such as
upright ears. We know from written descriptions and
pictures that Horand and Luchs had wolf/sable colored coats
indicating they carried at least one Aw
allele in their genotype and likely carried a full Aw/Aw
genotype. The picture is faded and not of high quality, but
the dog appears to have a dark mussel indicating he may
carry an Em allele in his genotype.
We also know their grandsire was white and that many of
their progeny had white coats too. From this information we
can deduce that one or both dogs carried a recessive e
allele in their MC1R genotype. Therefore, either one or
both Horand and Luchs must have had a MC1R genotype of at
least of E/e, and, if Horand
picture does indeed show he has a dark mussel, one or both
dogs had a genotype of Em/e.
If so, grandsire Greif then, likely carried an e/e
- aw/aw
genotype and Horand and Luchs inherited the E
and/or Em alleles from their
sable/wolf colored parents. Horand and Luchs then would
have had either a Em/e
- aw/aw
or E/e - aw/aw
"hidden white" genotype. From the first direct ancestors of
the German Shepherd Dog forward to modern German Shepherds,
the MC1R recessive allele for white colored coats has been
carried in the DNA of some portion of the breed. (Horand
photo left provided by Ruut Tilstra of the International
White Shepherd Federation10.)
White coats
were listed as disqualifications in the German Shepherd Club
of Germany breed standard in 1933, the American Kennel Club
(AKC) German Shepherd standard in 1968, the Canadian Kennel
Club German Shepherd standard in 1998, and the Australian
National Kennel Council German Shepherd list (standard) in
1994, at least partially, on the argument that white coats
are the result of an albinism condition that carries risks
of breed color paling and genetic health defects.
Genetic
research now reveals that one of the alleles that code for
white coats in the German Shepherd breed is at the MC1R
eumelanin regulation gene locus. The MC1R gene is
fundamental to overall German Shepherd Dog breed color
conformation and it is certainly unrelated to albinism. A
reasonable argument can be made that the recessive MC1R
e allele is somewhat analogous in magnitude of
function to the recessive solid black coat Agouti a
allele; Solid black coats are not specified as a German
Shepherd Dog breed standard disqualification.
We must
wait for further genetic research to give us positive
identification of the allele, or alleles, which regulate
phaeomelanin pigment production in hair follicle melanocytes
to complete our understanding of cream to white coat color
in the Shepherd breed. Even so, factual evidence is growing
against the argument that albinism explains white coat color
in the White German Shepherd, White Shepherd and White Swiss
Shepherd breed lines.
|
* - Stephanitz,
accompanied by his friend Artur Meyer, attended
the April 3, 1899 Karlesruhe Dog Exhibition, one
of the largest all breed dog shows to date, in
the Rhineland town of Karlesruhe. Stephanitz
and Meyer saw a herding dog name Hektor (Linksrhein)
von Sparwasser and immediately realized he had
found his ideal foundation dog. Hektor was born
the 1st of January 1895 along with litter
brother Luchs von Sparwasser, later registered
SZ-155. The breeder of Hektor and Luchs was
Herr Friedrich Sparwasser of Frankfort. Horand
whelped in Friedrich Sparwasser's Frankfort
kennel in (as Hektor von Sparwasser) together
with litter brother Luchs. Hektor is sometimes
referenced as Hektor Linksrhein with Linksrhein
referring to the Rhine region of his kennel.
Frankfort is close to the Rhine river on the
Rhine’s Main tributary and is considered to be
in the Rhine region.
Stephanitz at
once bought Hektor and renamed the dog Horand
von Grafrath. Horand is the first entry in the
German Shepherd Dog Club of Germany or Der
Verein für Deutsche Schäferhunde, or SV, Stud
Book as “Horand von Grafrath, SZ-1.
”Horand’s and
Luchs’ maternal grandfather was a white-coated
German herding dog named Greif von Sparwasser,
whelped in Friedrich Sparwasser's Frankfort
kennel in 1879. George Horowitz, renowned
English Judge, German Shepherd (Alsatian)
columnist, author and historian documents the
background of Hektor Linksrhein (a.k.a. Horand
von Grafrath) in his 1923 book, “The Alsatian
Wolf-Dog.” In his book Horowitz documents that
Greif von Sparwasser was presented at the 1882
and 1887 Hanover Dog Shows. Horowitz also
documents Greif's white progeny entered in shows
in succeeding years.
Greif von
Sparwasser was mated with female Lotte von
Sparwasser who whelped a litter that included a
wolf-grey colored female named Lene von
Sparwasser, later registered SZ-156. Both
Greiff and Lotta had the distinctive 'up right'
ears and a similar body conformation that we see
in the modern German Shepherd Dog breed. In
Lene's mating to dog Kastor (Rüde) von Hanau
SZ-153 she whelped a litter that included the
wolf colored Hektor (a.k.a. Horand von Grafrath
SZ-1) and his wolf colored litter brother Luchs,
SZ-155. Friedrich Sparwasser obviously had both
white and wolf (sable) colored herding dogs of
the same body conformation in his kennel and he
was pairing white and colored dogs in his
breeding program. Sparwasser's herding dogs are
described as originating from the German
Thuringia highland region.
Horand von
Grafrath, whelped in Friedrich Sparwasser's
Frankfort kennel in January 1895 as Hektor von
Sparwasser. Hektor is sometimes referenced as
Hektor Linksrhein with Linksrhein referring to
the Rhine region of his kennel. Frankfort is
close to the Rhine river on the Rhine’s Main
tributary and is considered to be in the Rhine
region. |
©Handley 2007 - email
mdhandley@yahoo.com
for permission to reprint
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©Handley 2007 - email
mdhandley@yahoo.com
for permission to reprint
|
