What is the Homozygous Black Gene?
The red coat color in horses is inherited as a trait recessive to black. A blood test for the red factor, based on DNA analysis, provides the information to determine what color offspring a horse can throw. The absence of the red factor presents itself as "E".
"E" = no red factor detected. The horse can be assumed to be homozygous for black pigment (EE). It cannot have red foals (chestnut or sorrel) regardless of the color of the mate.
A mare bred to a Homozygous black stallion can produce the following foal coat colors:
| Mare's Coat Color | Resulting Foal's Coat Color |
| Black | Black |
| Bay | Black or Bay |
| Chestnut or Sorrel | Black or Bay |
| Grey | Grey, Black, or Bay |
Note: This chart has been simplified to represent the most common coat colors.
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