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Many Breeders and potential buyers are looking for color (referring to any Pinto color) when looking at the Gypsy Horse or Drum Horse. We put together the following basic Genetic information to help those interested in the colored Gypsy or Drum.

Intro to Genetics - Because there are many variables when dealing with genetics we will cover only the basics. While on this topic...forget about the genetic color White!

What is a “gene”? A bit of DNA which acts as a code to control part of a cell's chemistry, such as producing proteins.

What is an “allele”? One form of a gene.

What is meant by Dominant? An allele that always expresses itself when it is partnered by a recessive allele or by another like itself.

What is meant by Recessive?
An allele which only expresses itself when it is partnered by another like itself.

What is Genotype? The type of alleles present for a particular Gene or genes, for example Tt

What is Phenotype? The way a gene works or expresses itself in practice.


Here are a few facts when looking at genetics. Genes are found on chromosomes. There are 64 chromosomes found in today’s horse! There are Dominant genes, represented with a capital letter, and Recessive genes, represented by a lower caps letter.
32 chromosomes are inherited from the stallion and 32, inherited from the
mare.

Looking at color genes...


Tobiano* - represented by the letter T. (Most common pinto color when referring to the Gypsy Horse)
Tobiano is a Dominant gene, meaning only one Dominant T gene needs to be passed on for the foal to display the Tobiano pattern. For example...if you have 2 Tobiano Horses both are genotyped with Tt, your chances of getting a Tobiano foal is 75%. In other words, in a perfect world, 75 out of 100 horses would be born displaying the Tobiano pattern. However if the resulting foal were to inherit only the t—or recessive Tobiano gene from both parents, although genetically still a Tobiano, it will be a solid color! Now, if you have a mare or stallion that have two Dominant T genes or TT, (also known as Homozygous), you will have a foal that is Tobiano no matter what you breed to, ideally. If you were to breed a Tt (horse displaying the Tobiano pattern) to a tt (a Horse not displaying the Tobiano pattern, but still genetically a Tobiano) your chances of getting a colored Tobiano horse is 50%.


Overo*—represented by the letter O.
Overo, also thought to be a dominant gene, follows basically the same rules as Tobiano genes, with few exceptions. So if you have an Oo foal it will display the Overo coat pattern. Oo will be a horse of solid nature. OO, Homozygous, is lethal. The foal will either be still born or die shortly after birth. This is know as Lethal White Overo, unfortunately there seems to be little information as to why.
It is important to note that there is not as much know about the Overo genetics as there is the Tobiano. It is thought that Overo may be caused by as many as 10 genes. There are documented cases where and oo solid horse has produced an Overo pattern from a genetically solid horse! This would suggest the Overo is recessive!

The Homozygous Horse. Homozygous refers to a horse that has two of the same dominant gene. For example TT. This horse will pass on one Dominant T gene no matter what other genetic cross. It is important to note that horses determined to have both Homozygous genes, do not necessarily always throw the visible coat pattern. There are many documented cases of Genetic homozygous horses producing a few solid offspring.
Currently there is not a laboratory test to identify the presence of the tobiano gene. Genetic markers linked to tobiano may help, but they cannot prove homozygosity since they are not direct tests for the tobiano gene.
Homozygous tobianos are identified on the base of evidence, via Progeny tests!
To qualify as a homozygous tobiano a horse must be the result of a breeding from two tobiano parents. The horse should have a characteristic tobiano pattern including ink spots.
Breeding this animal should produce all tobiano foals with the exception of a rare minimal white. A horse that produces five tobianos out of five solid mates is thought to have a 97% chance of being a homozygous tobiano.

Alleles - The alternative forms of each gene are called alleles. If both alleles are identical, then the horse is said to be homozygous at that gene; if the alleles are different, then the animal is said to be heterozygous at that gene. Both sets of genes function simultaneously in one cell. Often when the gene pair is heterozygous, one allele may be visibly expressed but the other is not. The expressed allele in a heterozygous pair is known as the dominant allele, the unexpressed one as the recessive allele. The presence of a recessive allele may be masked by a dominant allele, which leads to the expression "hidden recessive." Dominant alleles are never hidden by their related recessive alleles. This may help explain why a Homozygous horse may occasionally throw solid foals.

*Tobiano - (pronounced: tow be yah' no)
The pattern of a tobiano is evident from the moment of birth. The white areas characteristically cross over the topline and produce four white legs at least below the knees and the hocks. It is almost unheard of to see a Tobiano with solid legs!

*Overo - Also apparent from birth, the white color seems to go from the belly up! These horses will have no white crossing the topline of the horse. They also may have solid legs and generally have a nearly all white face. It is also common for the Overo horse to have a least one blue eye!

"Blue"

Well genetically speaking, The Blue color is caused by the Dominant "Roan" gene R. While "Blue Roan" is similar to grey in that they share individual white hairs spread throughout the coat - They are two different colors, caused by two different genes! Grey is caused by the Dominant Grey gene G. In normal situations a Blue Roan, must have Black legs, Mane, tail and head! However when you infuse the coat pattern Tobiano or Overo, what is the norm is changed a bit, because Tobiano patterns horses rarely have solid legs, manes or tails. For a horse to be considered "Blue" it must have a Roan gene present and it must be Base Black (EE or Ee)! If a horse is lacking pigment under the coat hair (the skin is white, not black) the horse can not be considered "blue".

Notes:-With very few exceptions, you will not see a Homozygous Roan. A foal born with two dominant roan genes is almost always still born or dies shortly after birth.

-Roan may occur in any base color - but the "blue" effect comes only from Base Black.

Typically Grey and White pinto colored Gypsy Horses are considered Blue and White by breeders across seas.

 

 

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