Created at the VGL Mushroom

Quick Summary

Mushroom is a dilute coat color found in Shetland Ponies that results in a distinctive “sepia” toned coat, often accompanied by a flaxen mane and tail.

Shetland Pony with Mushroom dilution. Photo credit: Maria Tammi

Phenotype: Mushroom is a dilute coat color found in Shetland Ponies that results in a distinctive “sepia” toned coat color, often accompanied by a flaxen mane and tail.

Mode of Inheritance: Autosomal recessive

Alleles: N = Normal or non-mushroom, Mu = Mushroom

Breeds appropriate for testing: Shetland Pony, Miniature Horse

Explanation of Results:

  • Ponies with N/N genotype will not have this mushroom dilution and cannot transmit this mushroom dilution variant to their offspring.
  • Ponies with Mu/N genotype will not have this mushroom dilution, but are carriers. They may transmit this mushroom variant to 50% of their offspring. Matings between two carriers result in a 25% chance of producing a mushroom foal.
  • Ponies with Mu/Mu genotype will show a dilute coat color on a red background, and will transmit this mushroom dilution variant to all of their offspring. Matings with other Mu/Mu genotype ponies are expected to produce all mushroom offspring.
Price

$25 one test per animal

Panels Available
Additional Details

Mushroom is a dilute coat color found in Shetland Ponies that is characterized by a distinctive sepia-toned body hair color, often accompanied by a flaxen mane and tail. The mushroom phenotype shows wide variation in shade and has similarities to cream and silver dilutions, although it is genetically distinct from both. Mushroom dilutes red pigment (phaeomelanin) and thus the dilute phenotype is most obvious on a chestnut base color.

Researchers at the Veterinary Genetics Laboratory and the University of Bern investigated the molecular basis of mushroom color dilution and identified a single nucleotide change in a pigmentation gene that explains this phenotype. Pedigree analysis suggests an autosomal recessive mode of inheritance for mushroom dilution. This means that the phenotype occurs in both males and females but only chestnut ponies with two copies of the mushroom variant have the characteristic mushroom dilute phenotype. Recent work at the Veterinary Genetics Laboratory suggests that bay horses homozygous for the mushroom variant may also have altered pigmentation in the coat. The mushroom mutation is present at a low frequency in Miniature Horses.

Testing for mushroom color dilution helps owners make breeding decisions. If the mushroom phenotype is desired, it is advisable to breed mushroom ponies to each other (e/e, Mu/Mu genotypes). Mating of two chestnut mushroom carriers (e/e, Mu/N genotypes) will result in a 25% chance of producing a mushroom pony. Testing for Mushroom and other coat color genes at the VGL (Agouti, Red Factor, Silver, Dun, Cream) will help owners to distinguish mushroom ponies from similar phenotypes caused by other genes.

Turnaround Time
2-6 business days
Type of Sample

Species

Type of Test

Results Reported As
Test Result Mushroom Dilution
N/N No copies of mushroom variant detected. Pony does not have mushroom dilution.
Mu/N

1 copy of mushroom variant detected. Pony is a carrier and does not have the mushroom dilution. Carriers can produce mushroom foals when bred to the appropriate mate.

Mu/Mu 2 copies of mushroom variant detected. Chestnut ponies with this genotype have the mushroom dilution.
References

Frederiksen, A. G. (2011). Genetic testing of silver Shetland Ponies for allelic variants of MC1R, ASIP and PMEL17 (Master’s Thesis). University of Copenhagen, Copenhagen, Denmark.

Sponenberg, P., & Bellone R. R. (2017). Equine Color Genetics, 4th Edition. Hoboken, NJ: Wiley-Blackwell.

Tanaka, J., Leeb, T., Rushton, J., Famula, T.R., Mack, M., Jagannathan, V., Flury, C., Bachmann, I., Eberth, J., McDonnell, S.M., Penedo, M.C.T., & Bellone, R.R. (2019). Frameshift Variant in MFSD12 Explains the Mushroom Coat Color Dilution in Shetland Ponies. Genes10, 826. doi: 10.3390/genes10100826.