Description
DNA test
Sample
- 30 to 40 - hair roots - envelope
or
- 5 mL - blood - K3 EDTA tube
Turnaround time
Why test?
- The DNA testing for the Extension gene can be used to identify those black horses for which neither pedigree nor breeding records is informative for identifying carriers of the recessive red factor.
- Since red is inherited as a recessive trait, it is relatively easy to start up a breeding program that will produce only red horses. It has been more difficult to initiate a black breeding program as black (Ee) horses can produce red foals.
Results description
The DNA test for Extension gene verifies the base coat color and presents results as one of the following:
-
E/E - Dominant Homozygous for Extension - Black, Bay or Brown - Only the black factor is expressed. The horse can only transmit the (E) allele E/E to it offspring. It cannot have foals with basic coat colour Chestnut or Sorrel foals regardless of the color of the mate. The Agouti gene will
determine if the basic coat color will be black, bay or brown, unless modified by other color modifying genes.
-
E/e - Heterozygous for Extension - Black, Bay or Brown - Both red and black factor are expressed. It can transmit either (E) or (e) allele to its offspring. The Agouti gene will determine if the basic coat color will be black, bay or brown, unless modified by other color modifying genes.
-
e/e - Recessive homozygous for Extension - Chestnut or Sorrel - Only the red pigment is expressed. The basic coat color is chestnut or sorrel unless modified by other color modifying genes.
Additional information
Equine coat color is built on one of two possible base pigments: red or black.
The Extension gene controls the production of this base pigment (red or black).
All horses will have the genetics for black or red pigment, regardless of their physical appearance. There are a number of dilutions patterns and modifiers, which a horse can carry that affect the base pigment of a horse.
The Extension gene (red factor) has two alternative states (alleles). The dominant allele (E) produces black pigment in the coat. The recessive allele (e) produces red pigment.
Red horses (chestnuts, sorrels, palominos…) are homozygous, that is they have two alleles, for the recessive red allele (e/e).
Black pigmented horses (black, bay, brown, buckskin…) have at least one (E) allele. They can be homozygous (E/E) or heterozygous (E/e).
A horse that is homozygous (E/E) will not produce red offspring, regardless of the color of the mate.
