Transcript Genetics in Horses

Color Genetics in Horses
Coat Color Genetics
• Theory
– Coat colors are just that, a theory.
• Research on coat color and genetics is an ongoing
research as new things are developed and discovered.
Genes
• Colors are passed on to
offspring through
genes.
• The offspring receive
genes from each of the
parents, creating their
own set of
chromosomes.
• Cell division- Sperm and
Eggs
Genes
• Dominant Genes- Just that, they are dominant.
This is the gene that is going to show. Dominant
is represented with a capitol letter (D).
• Recessive Genes- This gene is submissive to the
the dominant gene. Recessive is represented with
lower case letters (d).
• There are three possible outcomes.
– Two dominant genes. Example AA
– Two recessive genes. Example aa
• When there are two recessive genes, this is the color that
will show.
– One dominant, one recessive. Example Aa
• The dominant gene will be the color to show.
Gene Relationships
• Homozygous- referring to a gene pair that is
the same.
– Homozygous Dominant- gene pair with two
dominant genes (AA).
– Homozygous Recessive- gene pair with two
recessive genes (aa).
• Heterozygous- referring to a gene pair that has
one dominant and one recessive (Aa).
Punnett Square
• Punnett Square is a way
of determining a genetic
make-up. In this
situation, horse color.
• Punnett Square uses both
the genetic make-up of
the stallion and the mare
and helps us to determine
the possible outcomes of
the offspring.
Stallion is Homozygous Recessive for the red gene (red based
pigment) and represented with lower case letters (ee).
Mare is Heterozygous with the black gene (black based pigment)
being dominant and is represented with a capitol and lowercase
letter (Ee)
Stallion 
Mare
e
e
E
Ee
Ee
e
ee
ee
In this situation, there is a 50% chance of the colt have black based
pigment and a 50% chance of the colt having red based pigment.
Dilutions and Modifiers
• These are the genes that
create colors such as Duns,
Buckskins, Palominos and
Gray.
• Gray is a dominant gene. Gray
can affect any color both red
and black pigmented colors.
Gray is represented (G).
– Homozygous gray (GG)
• Will “gray-out”
– Homozygous Recessive (gg)
• This gray will not “gray-out”
however they carry the gray
gene.
– Heterozygous gray (Gg)
• Will “gray-out”, though generally
not as much as a GG will.
Dilution and Modifiers Cont.
• Dun horses are represented with (D). Horses that are
DD or Dd will have diluted color throughout their body
but the points such as legs, ears, mane, and tail will not
be affected by the dilution. A horse that is dd will NOT
be a dun.
• Dun horses can be both red based or black based and
represent the colors buckskin dun, red dun, or grulla.
• Dun horses are factored with base colored points and a
stripe down their back known as a dorsal stripe. They
may occasionally have striping in their points.
– A true buckskin will NOT have a dorsal stripe.
Buckskin Dun
Red Dun
Grulla
Cream Gene
• Cream is represented by
(Cr)
• A horse carrying CrCr will be
more diluted than a horse
with an nCr (normal cream).
CrCr horses are colors such
as cremellos, perlinos, and
smoky creams.
• nCr horses are colors such
as palomino, buckskin and
smoky black.
• nn (normal color) can be
represented as black, sorrel,
or bay.
Punnett Square
nCr X nCr
(Palomino X Palomino)
Stallion 
n
Cr
n
nn
nCr
Cr
nCr
CrCr
Mare
In this case there is 25% chance of nn (sorrel, black or
bay) 25% chance of CrCr (Cremello) and 50% chance of
nCr (Palomino).
References
http://www.coquatranch.com/colorpatternsgenetics.htm#283709091
http://www.equinestudiesinstitute.com/sample_genetics.htm