In-depth information for dog breeders, yellow coat color -ee alleles- which allows no dark pigment as in the South African Boerboels, by AKC Judge Fred Lanting.
Canine Coat Color Genetics, Part 3
Yellow Coated Dogs
Fred Lanting, All-Breed Judge, SAAB, Sieger/Schutzhund
In-depth information for dog breeders, yellow coat color - ee alleles - which allows no dark pigment, as in the South African Boerboels.
At first, I intended to satisfy this publication’s needs for succinct articles on coat color by submitting just two short introductory pieces on the genetics of coat colors as found in many breeds, using the little-known Boerboel as a primary example but…
In Part One, we discussed the Agouti coloration (think wolves), the inheritance of black, and the fact that there are only two basic colors in dog coats: black (including dilute variations), and “brown” although the latter has a multitude of names and shades from deep red to white-yellow.
In Part Two, some dogs have patterns referred to as “bi-color” or “saddle” which refer to a different (and darker) color on the dorsal parts than is seen on the ventral parts. Some have a “sable” pattern, in which that darker-lighter split is much less defined if at all. Some have no black in the coat at all.
Now in Part Three, we’ll concentrate on that third group, the ones that have no black in the coat, although they may have such in the integument (nose, lips, claws, etc.) which is governed by different genes than the coat-color pattern ones.
Genes are macromolecules or combinations of molecules that do not change or break apart. They are located on chromosomes which do split and recombine differently in certain circumstances. Together, these organic genetic chemicals determine the phenotype (the appearance of the offspring) and the genotype (what the offspring has inherited and can pass along to the next generation. The slight differences in inherited genes are called alleles.
The gene that has been identified as Melanocortin Receptor 1 (MC1R) and is located on chromosome number 5 in the dog (this “residence” known as the E locus) is the one that controls whether or not to allow black (including chocolate or blue) in the haircoat. There are two main alleles (variations) of this gene, and they are given the capital and subcase designations: E and e, this letter being chosen because it stands for eumelanin. Remember that cells contain two genes (alleles) and they can be either the same or different versions—for example, a dog that has one E and one e is said to “carry” the recessive e (no expression of dark pigment) although it is dominated by the “stronger” E (positive expression of dark). If both members of the pair are e, then no dark hair (black, blue, liver) can be seen or passed on to offspring.
Thus, dogs that have a double dose of the recessive e will be non-black (that
is, some shade between deep red and near-white yellow) and can only contribute
one e allele to their offspring via sperm or egg cells which of course carry
only one copy instead of the two alleles in every other body cell. The e allele,
when present in double dose (one from each parent), instructs the cells in the
haircoat to arrange or disperse pigment granules in such a way as to show a
yellow shade. One of the most popular breeds worldwide is an example of this:
the Labrador Retriever. You can find the widest range of color in “yellow Labs”
yet all will be alike in having that double dose, ee alleles for coat color.
They may be produced by pairings of dark dogs—black or chocolate (no blues are
in the breed)—or by two yellow Labs, or a pairing of one of each, as long as the
pup gets an e allele from each parent.
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Fred Lanting is an all-breed judge with experience in over 30 countries. He is a well-known Shiba breeder and GSD authority. He handled Akitas in the 1960s and `70s, and was named an official JKC judge, a rare honor. He has lectured around the world on breeding, judging, canine movement, and CHD (canine hip dysplasis). Be sure to peruse these Dog Books by Fred Lanting