Mushroom is one of the dilutions present in horses.
¶ Phenotype
Mushroom only affects red pigment, and therefore only shows on chestnut- and bay-based horses. It dilutes the coat to distinctive “sepia” toned coat, often accompanied by a “flaxen” mane and tail. The coat colour can show a wide shade variation and can have similarities to cream and silver.
| Mushroom - Shetland Pony | |
| Example | Information |
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Chestnut Mushroom Chestnut mushroom horses have a distinctive sepia-toned colour, often with a lighter mane and tail.
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Bay Mushroom Bay mushrooms lack the reddish hue of a typical bay coat, with countershading on the top line (darker head, neck, shoulders). |
¶ Genotype
Mushroom is caused by a frameshift mutation of the MFSD12 gene on the ECA7-Locus. This gene has been shown to play an important role in melanogenesis, specifically in determining the quantity of eumelanin and pheomelanin, in many other species. It is hypothesised that the mushroom mutation in horses results in a decrease in pheomelanin production, leading to diluted chestnut and bay coats. Simultaneously, it is hypothesised to increase eumelanin production, leading to the darker countershading seen on bay-based horses.
Mushroom is recessive, meaning a horse will need 2 copies for the coat to be diluted.
Below, the resulting phenotype of each genotype is listed:
- mu/mu = Mushroom
- mu/n = Not mushroom (mushroom carrier)
- n/n = Not mushroom
The presence of the mushroom allele can be tested at the Laboratory.
¶ Breeds
The mushroom dilution can be found in Shetland Ponies and also rarely in Miniature Horses. The following table lists all breeds that can currently have the mushroom allele in-game.
| Breeds |
| Akhal-Teke Horse |
| Arabian Horse |
| Brabant Horse |
| Brumby Horse |
| Camargue Horse |
| Cleveland Bay |
| Exmoor Horse |
| Finnhorse |
| Fjord Horse |
| Friesian Horse |
| Haflinger Horse |
| Icelandic Horse |
| Irish Cob Horse |
| Kladruber Horse |
| Knabstrupper |
| Lipizzaner |
| Lusitano |
| Mongolian Horse |
| Mustang Horse |
| Namib Desert Horse |
| Noriker Horse |
| Norman Cob |
| Oldenburg Horse |
| Pantaneiro Horse |
| Pura Raza Española |
| Quarter Horse |
| Shetland Pony |
| Shire Horse |
| Suffolk Punch |
| Thoroughbred |
| Trakehner Horse |
| Welsh Pony |
¶ References
- Tanaka J. et al, Frameshift Variant in MFSD12 Explains the Mushroom Coat Color Dilution in Shetland Ponies, Genes, 2019
- UC Davis Veterinary Genetics Laboratory; https://vgl.ucdavis.edu/test/mushroom; Access: June 2023
- Generatio Center for Animal Genetics; https://generatio.de/en/guidance/lexicon/mushroom-horse; Access: June 2023