Horse Chestnut Variant E (extension e)

The Chestnut Variant E (Extension e) DNA test in horses is essential for breeders aiming to understand coat color genetics. This test identifies the presence of the Extension gene variant responsible for red-based chestnut coloring. By analyzing the Extension e allele, breeders can predict offspring coat colors more accurately and make informed breeding decisions. The Chestnut Variant E test is quick, reliable, and widely used in equine genetic testing. Understanding this gene helps maintain breed standards and enhances the value of your horse. For optimal breeding outcomes, include the Extension e DNA test in your genetic panel today. Accurate genetic insights lead to healthier, more vibrant chestnut horses.

Abbreviation : extension e

Analysed mutation : MC1R c.248C/T

Inheritance : Autosomal Recessive

Acronym

extension e

Observed frequency

Common

Clinical classification

Coat-Related Traits

Analysed mutation

MC1R c.248C/T
p.(S83F)

Mode of inheritance

Autosomal Recessive (Complete)

Alternate name:

E Locus

Test summary:

The Chestnut Variant E (Extension e) in horses is a specific genetic marker that influences coat color. This variant affects the production of red pigment, resulting in chestnut or sorrel coat shades. Horses with the Extension e allele typically lack black pigment in their hair. DNA testing for this variant helps breeders predict and select desired coat colors. Understanding this gene is important for accurate breeding and color identification.

Available from the pack : Standard

This DNA test is included starting from our pack Standard — and is also part of the packs Standard, Advanced, Complete.

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Introduction to Chestnut Variant E (Extension e)

The Chestnut Variant E, also known as the extension e allele, is a genetic trait found in horses that influences coat color. This variant is crucial for understanding the inheritance patterns of chestnut coloration in equines. The extension gene is responsible for the production of red pigments in a horse's coat, and its presence or absence determines whether a horse will exhibit chestnut, bay, or black coloration.

Genetic Basis of Chestnut Variant E

The extension locus (E) is located on equine chromosome 3 and plays a significant role in the pigmentation of a horse's coat. The dominant allele 'E' allows for the production of eumelanin, which is responsible for black and bay coats. Conversely, the recessive allele 'e' inhibits eumelanin production, resulting in a chestnut coat. Horses with two copies of the 'e' allele (ee) will display a chestnut coat color, while those carrying at least one 'E' allele will not.

Phenotypic Expression

While the presence of the extension e allele predominantly results in a chestnut coat color, various phenotypic expressions can occur based on other interacting genes. Factors such as sabino, roan, or varnish patterns may alter the appearance of the coat, even in horses that test positive for the extension e variant. The intensity of the chestnut coloration can also vary, with some horses exhibiting a deep, rich chestnut and others presenting a lighter, more golden hue.

Importance of Genetic Testing

DNA testing for the Chestnut Variant E is essential for breeders and owners who wish to understand and predict coat color inheritance in their horses. By knowing whether a horse carries the extension e allele, breeders can make informed decisions about pairings to achieve desired coat colors in future offspring. Additionally, genetic testing can help identify potential health implications associated with specific coat color traits, allowing for more responsible breeding practices.

Conclusion

The Chestnut Variant E (extension e) is a key genetic marker in the study of horse coat color inheritance. Understanding this variant not only aids in predicting coat color outcomes but also enhances the overall knowledge of equine genetics. As the field of equine genetics continues to evolve, DNA testing for the extension e allele remains a valuable tool for breeders and enthusiasts alike, contributing to the responsible breeding and management of horse populations.

Breed recognized for the test : Chestnut Variant E (extension e)

Arab
Belgian Draft
Clydesdale
Freiberger
Icelandic Horse
Morgan
Quarter Horse
Shetland Pony
Standardbred
Thoroughbred
Warmblood
Welsh Pony

Interpretation of genotypes Genotype Status Learn more about the interpretation of genotypes FAQ: understanding the interpretation of result What does “Clear” mean? The animal does not carry the mutation. It will not develop the disease and will not pass it on. Is a “Carrier” serious? No. The animal is generally healthy but can transmit the mutation to its offspring. What if an animal is “Affected”? It carries two mutated copies. Clinical signs are expected depending on the disease. It should not be bred. Why are there differences between male / female? Some diseases are sex-linked, so their expression varies depending on the animal’s sex. The animal has two normal copies of the gene. No risk of developing or transmitting the disease. Heterozygous carrier: one mutated copy. The animal is usually not clinically affected but can pass the mutation to offspring. Male carrier or affected depending on the inheritance mode. Males have only one X or Y chromosome. Heterozygous female carrier: one mutated copy. She can pass the mutation on and may sometimes show mild clinical signs depending on the condition. Two mutated copies of the gene. The animal is at risk of developing the associated condition.

🧬 Interpretation of genotypes extension e

Genotype

Status

🟡 E/E

Non-carrier - No effect

🟡 E/e

Carrier - No effect

❌ e/e

Affected - Chestnut

FAQ: understanding the interpretation

What does “Clear” mean?

The animal does not carry the mutation. It will not develop the disease and will not pass it on.

Is a “Carrier” serious?

No. The animal is generally healthy but can transmit the mutation to its offspring.

What if an animal is “Affected”?

It carries two mutated copies. Clinical signs are expected depending on the disease. It should not be bred.

Why are there differences between male / female?

Some diseases are sex-linked, so their expression varies depending on the animal’s sex.

Genotype Forecast for Offspring Mother Father Non-carrier Carrier Affected Favorable cross: majority Carrier risk is predominant. Majority affected Filter by mother's genotype Filter by father's genotype All Predict Offspring The animal has two normal copies of the gene. No risk of developing or transmitting the disease. Heterozygous carrier: one mutated copy. The animal is usually not clinically affected but can pass the mutation to offspring. Male carrier or affected depending on the inheritance mode. Males have only one X or Y chromosome. Heterozygous female carrier: one mutated copy. She can pass the mutation on and may sometimes show mild clinical signs depending on the condition. Two mutated copies of the gene. The animal is at risk of developing the associated condition.

Predict Offspring

Filter by mother's genotype Filter by father's genotype

E/E (Non-carrier)

E/e (Carrier)

e/e (Affected)

DNA Test FAQ

What does this DNA test detect?

This DNA test detects the mutation associated with Chestnut Variant E (extension e) in order to identify clear, carrier, or at-risk animals.

Why test a breeding animal?

DNA testing helps breeders plan safer matings and reduce the risk of transmitting the mutation to offspring.

What is the inheritance mode of this test?

The inheritance mode reported for this test is Autosomal Recessive.

Which mutation is analysed in this test?

This test analyses the mutation MC1R c.248C/T.

Is a carrier animal necessarily affected?

Not necessarily. Interpretation depends on the inheritance pattern and the resulting genotype.

References

Marklund L, Moller M J, Sandberg K, Andersson L. A missense mutation in the gene for melanocyte-stimulating hormone receptor (MC1R) is associated with the chestnut coat color in horses. Mamm Genome. 1996 Dec;7(12):895-9. doi: 10.1007/s003359900264.

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