Gray

Quick Summary

The gray gene causes progressive depigmentation of the hair, often resulting in a color that is almost completely white by 6-8 years of age. The individual gray test will determine the number of copies of the gray allele (zygosity). The coat color panel tests detect presence or absence of the gray allele.
Search Keywords
gray
grey

Gray Horse Example
Andalusian with the gray gene showing progressive depigmentation

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Phenotype: The gray gene causes a progressive depigmentation of the hair, often resulting in a color that is almost completely white by 6-8 years of age, and can act on any base coat color.

Mode of Inheritance: Autosomal dominant

Alleles: N = Normal or non-gray, G = Gray

Breeds appropriate for testing: Many breeds

Explanation of Results:

Graying Foal
Warmblood foal displaying progressive depigmentation. Photo used with permission of Mary King Messenger.

  • Horses with N/N genotype will not be gray and cannot transmit this gray variant to their offspring.
  • Horses with N/G genotype will be gray and will show a progressive graying of the coat. They may transmit this gray variant to 50% of their offspring. Matings with N/N genotype will result in a 50% chance of producing a gray foal.
  • Horses with G/G genotype will be gray and will show a progressive graying of the coat. They will transmit this gray variant to all of their offspring.

If gray is tested as part of a coat color panel, results are reported as:

  • present which means the gray allele was detected and horse will gray or
  • absent in which the gray allele was not detected and therefore the horse will not turn gray.

Price

$25 one test per animal

Panels Available
Turnaround Time
At least 15 business days; may be delayed beyond 15 business days if sample requires additional testing, or a new sample is requested.
Additional Details

Gray Horse Example #2
Andalusian with the gray gene showing depigmentation progressing toward an almost completely white coat

The gray gene causes progressive depigmentation of the hair, often resulting in a coat color that is almost completely white by the age of 6-8 years. Horses that inherit progressive gray can be born any color, then begin gradually to show white hairs mixed with the colored throughout the body. Usually the first signs of gray hair can be found on the head, particularly around the eyes.

Gray is dominant, therefore a single copy of the gray allele will cause a horse to turn gray. If a horse has two copies of gray, all offspring of this horse will be gray. Research indicates that horses with one copy of gray often retain some of the original pigment while horses with two copies of gray tend to progress to almost completely white.

Gray is found in many breeds and is the predominant color of the Lipizzan breed. Researchers at Uppsala University in Sweden discovered that a 4.6 kilobases duplication in intron 6 of gene syntaxin 17 (STX17) produces progressive graying in horses. Their research hypothesized that the mutation in STX17 affects the production of melanocytes and thus predisposes gray horses to melanoma as well as causes the graying of the coat.

Gray Horse Example 3
Arabian with the gray gene showing depigmentation resulting in an almost completely white coat color

Gray horses have a high incidence of dermal melanomas that are commonly seen around the tail and head. Over 70% of gray horses older than 15 years will develop melanoma. Gray homozygotes are more likely to develop melanoma than heterozygotes. Gray horses that are also homozygous for black (a/a genotype at the Agouti locus) have a higher risk for melanoma. Many gray horses show depigmentation of the skin around the eyes, mouth, and anus, but there are no known additional health risks associated with this condition.

Testing for this gray variant can help owners identify homozygous horses (animals with two copies of the variant) which will always produce gray offspring, and can assist in determining a foal's coat color, as gray is a progressive pigmentation pattern.

 

 

Note: If the gray test is included in a panel, the test only detects presence or absence of gray. The panel report does not provide the number of copies (zygosity) of the gray gene. If zygosity information is desired, please order the gray test separately.
Type of Sample
20-30 Hairs With Roots

Species

Horse

Breed

Akhal Teke American Sport Horse American Sport Pony American Warmblood Andadura Andalusian Appalachian Singlefoot Appaloosa Appendix Arabian Ardennes Arriador Australian Stock Horse Azteca Baden-Wurttemberg Barockpinto Baroque Pinto Bashkir Curly Bavarian Belgian Belgian Sport Horse Belgian Warmblood Brandenburg Breton British Sport Horse British Spotted Pony Bucking Horse Burchell's Zebra Caballo Deportivo la Silla Camarillo White Canadian Horse Canadian Warmblood Caspian Horse Chapman's Zebra Chilean Horse Cleveland Bay Clydesdale Cob Normand Coldblooded Trotter Colorado Ranger Comtois Connemara Pony Continental Warmblood Costa Rican Paso Horse Cream Draft Criollo Crossbred Curly Dales Pony Danish Warmblood Deutsches Reitpony Deutsches Sportpferd Draft Cross Dutch Harness Horse Dutch Warmblood Exmoor Pony Falabella Faux Friesian Fell Pony Finnhorse Fire Friesian Frederiksborg French Warmblood "Selle Francais" Friesian Friesian Cross Friesian Sporthorse Georgian Grande German Riding Pony Gotland Pony Grevy's Zebra Gypsian Gypsy Cob Gypsy Vanner Hackney Horse Hackney Pony Haflinger Half Andalusian Half Arabian Half-Marchador Hanoverian Hartmann's Zebra Heck Tarpan Hessen Hibrido Highland Pony Holsteiner Iberian Warmblood Iceland Pony Icelandic Horse Imperial Heritage Horse International Sport Pony Irish Draught Irish Hunter Kallblodstravare Kentucky Mountain Horse Kerry Bog Pony Kiang Kiger Mustang Knabstrupper Kulan Latvian Warmblood Lipizzaner Lusitano Mangalarga Mangalarga Marchador Mexican Sport Horse Miniature Horse Missouri Fox Trotter Mongolian Domestic Horse Morab Morgan Horse Moriesian Moroccan Barb Mountain Pleasure Horse Mule Mustang National Show Horse New Forest Pony Newfoundland Pony Nokota Noriker North American Trakehner Norwegian Fjord Horse Norwegian Nordland Oldenburg Onager Other Paint Horse Paso Fino Percheron Performance Horse Int'l Peruvian Horse Pinto Polish Warmblood Pony of the Americas Przewalski Pura Raza Española Quarter Horse Racking Horse Rheinland Rheinland Pfaltz-Saar Rhenish German Coldblood Rocky Mountain Horse Russian Orloff Russian Warmblood Saddlebred Saxon-Thuringian Coldblood Scottish Highland Pony Selle Français Shetland Pony Shire Shire Crossbred Silesian Horse Sillo Argentino Single-Footing Horse South German Coldblood Spanish Barb Spanish Heritage Horse Spanish Mustang Sporthorse Spotted Saddle Horse Standardbred Suffolk Punch Swedish Warmblood Tarpan Tennessee Walking Horse Thailand Pony Thoroughbred Trakehner Trocha Trocha y Galope Trote y Galope Turbo Friesian Unknown Uruguayan Criollo Virginia Warmblood Warlander Welsh Pony Weser Ems Ponies Westfalen Wild Horse Zangersheide
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Type of Test

Coat Color and/or Type
Results Reported As
Test Result Gray
N/N No copies of the gray gene. Horse will not turn gray.
N/G 1 copy of the gray gene. Horse will turn gray and approximately 50% of offspring will be gray.
G/G 2 copies of the gray gene. Horse will turn gray and all offspring will be gray.

For panel tests, results are reported as:

  • present which means the gray allele was detected and horse will gray or
  • absent in which the gray allele was not detected and therefore the horse will not turn gray.
References

Pielberg, G. R., Golovko, A., Sundström, E., Curik, I., Lennartsson, J., Seltenhammer, M. H., Druml, T., Binns, M., Fitzsimmons, C., Lindgren, G., Sandberg, K., Baumung, R., Vetterlein, M., Strömberg, S., Grabherr, M., Wade, C., Lindblad-Toh, K., Pontén, F., Heldin, C.H., Sölkner, J., & Andersson, L. (2008). A cis-acting regulatory mutation causes premature hair graying and susceptibility to melanoma in the horse. Nature Genetics, 40(8), 1004-1009. doi: 10.1038/ng.185

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