Dog coat genetics
First we will go over the basics-
DNA: Every cell has a copy of the individual genetic properties. This is DNA
Chromosomes: Masses of DNA visible during cell division. Chromosomes come in pairs, so there are two copies of DNA. (Sex chromosomes are the exception to this rule)
Locus/Loci: Locus is Latin for Location. This is the name of the AREA on the DNA that codes for a specific property.
Alleles: The Alleles is the content of the Locus. They are either DOMINANT or recessive IE; in the coat color Locus the Alleles are B (black) b (brown)
Gene: Since DNA is two strands together, every Locus can fit two Alleles(Again sex chromosomes are the exception)
Phenotype: Visual, this is how one looks on the outside but doesn't nessicarily represent the actual gentics.
Genotype: Genes, this is the actual genetic make up. May, or may not be visual.(IE: Cryptic merles)
Example Coat Color= B(Black-dominant) b(brown-recessive)
Black(BB) breed to brown(bb)
You get all Black pups but they all carry brown(commonly called red in the US)
Now if you take these pups and breed them with another brown carrier you get:
You get 50% Black(brown carriers), 25% Black(non-carriers) and 25%Brown
Ok now onto the specifics!
When it comes to a dogs coat color, there is a path or order. Some genes mask others. You can't always tell what a dogs coat color is just by looking at it.
All the coat colors and patterns are a result of the different Loci and how they affect the eumelanin (black pigment) and phaeomelanin (yellow/tan pigment) in each hair.
The first stop is E (Extension) this has the ability to mask every visual color/pattern that the coat actually has. If it is (e-e) that means there is no eumelanin and only phaeomelanin is expressed.(Golden Retrievers)
Since everything else is modifiers of eumelanin we stop there because the dog's coat will only have phaeomelanin. The amount of phaeomelanin varies; I(intensity)Locus. Or diluted; C(chinchilla)Locus
E Locus controls Emuelanin in the hair. Gene:MCR1
Em Melanistic Mask The color of the melanistic mask corresponds with the other genes affecting the production of the eumelanin type. It is not always black.
Eg Grizzle/Domino eumelanin is expressed from the head, dorsal stipe and tail.
E Eumelanin present in the entire coat.
e Eumelanin suppressed (only phaeomelanin in the hair)
K locus controls whether the hair will have phaeomelanin. Gene:CBD103
K (Dominant Black)
KB This will completely mask the A(agouti) Alleles. A tri-point with KB Alleles will not be visible.
kbr This is brindle. It will make a coat brindle or brindle points depending on the A(agouti) Alleles
ky This will allow the A(agouti) Alleles to show.
A locus controls how/where the phaeomelanin will show in the hair. Gene:ASIP
at Tan point
a Recessive Black- No phaeomelanin in the coat.
B Locus controls the synthesis(how much)of eumelanin. Gene:TYRP1
D Locus controls the shape of the pigment cells. Gene:MLPH
With d-d the pigment cells are fewer and larger. This gives the dilute color. Black becomes blue and brown becomes lilac.
D Not diluted
I Locus controls how much phaeomelanin is in the hair. Gene:(?)
C Locus controls dilution in phaeomelanin in the hair. Gene:TYR
C Pigment present
c Albino (no pigment)
ce Extreme chinchilla
cp Platinum (ivory)
G Locus controls progressive greying of eumelanin. Gene:(?)
g No greying
M Locus is a pattern gene and randomly dilutes eumelanin. Gene:(PMEL)
m Non merle
H Locus is a modifier of merle. It removes the diluted areas to white. Gene:(PSMB7)
H Harlequin(only when merle is present)
h Non harlequin
Tw Locus is a modifier of merle. It changes the diluted areas to varying shades/colors Gene:(?)
Tw Tweed(only when merle is present)
tw Non tweed
S Locus is a pattern gene. It removes pigment showing only white. Gene:(MITF)
S Solid coat, no white
si Irish spotting pattern (typical Border Collie markings)
sp Piebald, white with some markings
sw Extreme white, little to no markings
T Locus is a pattern gene. It adds small spots of pigment in white areas. Gene:(?)
T Ticking only in white areas
t Non ticking
R Locus is a pattern gene. It adds pigmented hairs intermixed with white hairs. Gene:(?)
R Pigmented hairs mixed in white areas
r No pigmented hairs in white areas
L Locus affects the length of the hair. Gene:(FG5F)
Hr Locus determines if the coat will have hair or not. Gene:(FOXI3)
Wh Locus affects the texture of the hair. Gene:(RSPO2)
Wh Wire/rough hair
wh smooth/soft hair
Cu Locus affects the curlyness of the hair. Gene:(KRT71)
Cu Curly hair(Poodles)
cu Straight hair
R Locus produces a ridge of hair along the dorsal/spine. Gene:(duplication of FGF3,FGF4,FGF19)
R Ridged(Rhodesian Ridgeback)
Rp Locus produces ripples in the dogs coat. Only known in Weimaraners. Gene:(?)