Genetic Formulas
and Color Definitions

Genetic Formula
Horse Color
W
White
G
Gray
E, A, CC, dd, gg, ww, toto
Bay or Brown
E, aa, CC, dd, gg, ww, toto
Black
ee, aa, CC, dd, gg, ww, toto
Red: Sorrel or Chestnut
E, A, CCcr, dd, gg, ww, toto
Buckskin
ee, CCcr, dd, gg, ww, toto
Palomino
ee, CcrCcr

Cremello

E, CcrCcr

Perlino
E, A, CC, D, gg, ww, toto
Buckskin Dun
E, aa, CC, D, gg, ww, toto
Mouse Dun or Grulla
ee, CC, D, gg, ww, toto
Red Dun
gg, E, aa, CC, dd, RN
Black Roan (Blue Roan)
gg, E, A, CC, dd, RN
Bay Roan (Red Roan)
gg, ee, CC, dd, RN
Red Roan (Red Roan)
gg, E, A, CCcr, dd, RN
Buckskin Roan (Red Roan)
gg, ee, CCcr, dd, RN
Palomino Roan (Red Roan)
gg, E, A, CC, D, RN
Buckskin Roan (Red Roan)
gg, E, aa, CC, D, RN
Mouse Dun Roan or Grulla Road (Blue Roan)
gg, ee, CC, D, RN
Red Dun Roan (Red Roan)
E, A, CC, dd, gg, ww, TO
Bay Tobiano
ee, CC, D, gg, ww, TO
Red Dun Tobiano

Terms:

Genes: the DNA/genetic information for ahorse is coded on strands of protein found in the nuclei of cells. A gene is an actual DNA sequence or spot on the strnads that can be identified with a specific characteristics, such as coat color.

Homozygous/Heterozygous: these terms relate to the gene pairs at a specific location. If the genes are homozygous, then they are the same. Heterozygous means they are different. (Example: Palominos are always heterozygous for the cremello gene, cremellos are always homozygous.)

Genotype: The genetic makeup of a horse.

Phenotype: The physical makeup of the horse - visible traits.

Alleles: One of the variant forms of a gene at a particular locus, or location, on a chromosome. Different alleles produce variation in inherited characteristics such as hair color or blood type. In an individual, one form of the allele (the dominant one) may be expressed more than another form (the recessive one).

Alleles and Actions
Gene
Alleles
Effect of Alleles in Homozygous & Heterozygous
W

 

W

w

 

WW: Lethal

Ww: Horse typically lacks pigment in skin, hair & eyes appear to be white

ww: Horse is fully pigmented

G

 

G

g

 

GG: Horse shows progressive slivering with age to white or flea-bitten, but is born any non-gray color. Pigment is always present in skin and eyes at all stages of silvering.

Gg: Same as GG.

gg: Horse does not show progressive silvering with age.

E

 

E

e

 

EE: Horse has ability to form black pigment in skin and hair. Black pigment in hairm ay be either in a points pattern or distributed overall.

Ee: Same as EE.

ee: Horse has black pigment in skin, but hair pigment appears red

A

 

A

a

 

AA: If horse has black hair (e), then the black hair is in points pattern. A has no effect on red (ee) pigment.

Aa: Same as AA.

aa: If horse has black hair (E), then that black hair is uniformly distributed over body and points. A has no effect on red (ee) pigment.

C

 

C

c

 

CC: Horse is fully pigmented.

CCcr: Red pigment is diluted to yellow; black pigment is unaffected.

CcrCcr: Both red and black pigments are diluted to pale cream. Skin and eye color are also diluted.

D

 

D

d

 

DD: Horse shows a diluted body color to pinkish-red, yellow-red, yellow or mouse gray and has dark points including dorsal stripe, shoulder stripe and leg barring.

Dd: Same as DD.

dd: Horse has undiluted coat color.

TO

 

TO

to

 

TOTO: Horse is characterized by white spotting pattern known as tobiano. Legs are usually white.

Toto: Same as TOTO

toto: No tobiano pattern present.

(Back to the Color Wheel)

(Home)