Silver dapple gene

[1] It is responsible for a group of coat colors in horses called "silver dapple" in the west, or "taffy" in Australia.

Silver dapple foals can be difficult to identify, but commonly have a pale, wheat-colored body coat, white eyelashes, and hooves with tapering vertical stripes.

PMEL17 is active from quite early in embryonic development through to the mature cell's melanosome and is involved with the production of the black pigment eumelanin.

By contrast, horses which lack a functional agouti gene cannot produce such alternating bands, and thus have wholly black coats with no visible phaeomelanin.

Chestnut horses lack the ability to manufacture eumelanin altogether, and so have wholly red coats devoid of true black pigment.

[2] The dilution changes black into various shades of platinum, silver and flat grey, though the original black-brown character of the color is usually preserved.

On the template of a black horse, which has a coat rich in eumelanin, the effect is that of complete conversion to varying shades of silver.

MCOA has multiple clinical signs including a bulbous bulging of the eye,[6] cornea globosa, severe iridal hypoplasia, uveal cysts, cataracts, and in a few cases, retinal detachment.

In Rocky Mountain Horses, the silver dapple color is sometimes associated with Anterior Segment Dysgenesis (ASD) which affects the structures in the face and the front of the eye.

Black silver horse exhibiting strongly diluted long hair with darker roots and flat gray, dappled body color
The points of a bay are black, while those of a silver bay (shown here) are silver.
Silver dapple foal exhibiting typical wheat-colored coat and pale eyelashes
The front two Rocky Mountain Horses have the silver dapple dilution.
Bay silvers retain their reddish body color with black points diluted to silver.
Eye disorders in horses with the silver dapple gene