Mushroom gene

Mushroom is a yet to be mapped, theorized recessive dilution gene that fades red pigment in a horse's body hair coat. On a chestnut base coat the horse is born a pale beige with sometimes a greyish or pinkish tint and often keeps that color when it becomes an adult, but some turn darker when an adult.

Mushroom on a bay base

A mushroom foal with a bay base

On a bay base the horse is born a yellowish beige with a dark contrast stripe on the back, and as it grows older the horse will resemble a buckskin.

The dilution has appeared to date only in a few Shetland ponies in the United Kingdom. Originally suspected to be the silver dapple gene, several ponies with this colour have been tested for the extension gene and results have been negative, thus verifying that it appears to affect pheomelanin ("red" (chestnut)) pigment.^[1]

References

• http://www.kellas-stud.co.uk/mystery.htm
• http://www.tawnyhorse.com/mushroom

Equine coat colors
Base coat colors	Extension (MC1R) base colors Black Chestnut (also known as Sorrel) Agouti (ASIP)-influenced colors Bay Seal brown
Gray	Gray
Dilution genes	Champagne Cream Buckskin Palomino (also known as Isabelline) Smoky black Cremello Perlino Smoky cream Dun (see also Blue dun or Grullo) Pearl Silver dapple
White	Dominant white Sabino-white Lethal white syndrome
Horse markings and patterns	Pinto patterns Overo Splashed white Frame Sabino Tobiano Tovero Base color variations (primarily UK English) Piebald Skewbald Tricoloured Leopard complex Varnish roan See also Appaloosa and Knabstrupper Roaning patterns Roan Rabicano
Other	Bend-Or spots Brindle Cropout Liver Pangaré Point coloration Primitive markings Sooty Flaxen Mushroom
Genetics and breeding	Equine coat color genetics Color breed Horse genome Wildtype Melanin Agouti signalling peptide KIT gene Endothelin receptor type B STX17 (Gray)
Category:Horse coat colors