Coat Colour Mushroom

Mushroom is a distinctive dilute coat colour characterized by a sepia-toned or taupe body, often accompanied by a flaxen mane and tail. The shade can vary widely between individuals and may resemble other dilutions such as cream or silver, though it is genetically unrelated to either.

This unique colouration is caused by an autosomal recessive mutation in the major facilitator superfamily domain containing 12 (MFSD12) gene. The mutation specifically affects red/yellow pigment (phaeomelanin), leading to visible dilution primarily on chestnut-based horses.

The mushroom gene is most commonly found in Shetland Ponies, with lower frequency observed in Miniature Horses.

The mushroom mutation primarily affects red-based coat colours because it dilutes phaeomelanin, the pigment responsible for red/yellow tones in horse coats. This means that a horse with a red-base (chestnut) shows a classic mushroom look with a diluted coat colour to a sepia, taupe, or mousy brown tone with flaxen or silvery manes and tail. On the basic colour bay the mushroom variant shows a sepia coloured body hair but no influence on the black lower legs, mane and tail, which are caused by eumelanin. These horses can resemble a faded or diluted bay, with a more distinctive muted tone. There is no visible effect of mushroom on horses with a black base coat even if the horse is homozygous for the variant.

Coat colour is an intricate trait that involves a combination of multiple different genes. Testing for a range of different loci will give the most complete prediction of a horse's coat colour genetics.

Pubmed ID: 31635058

Year published: 2019

Omia ID: 2197

Omia variant ID: