Dun

Dun is a dominant gene that dilutes the color of body hair, leaving the points and head unaffected. Dun horses also show 'primitive markings' consisting of a dark dorsal stripe, leg barring, shoulder stripes and concentric marks on the forehead (spiderwebbing, cobwebbing). The dorsal stripe appears to be a consistent feature of dun horses while the other 'primitive marks' vary and may not all be present, or visible. The effect of the Dun gene on the base colors of chestnut, bay and black produces horses with shades that range from apricot, golden, dark gray, olive, and many, more subtle, variations. Dun is inherited independently of other coat color genes and can occur in combination with any other genes that modify the base colors. Three variants in DNA sequence explain phenotypes related to Dun dilution: D (presence of dun dilution and primitive markings), nd1 (not Dun-diluted, primitive markings are present but expression is variable), nd2 (not Dun-diluted, primitive markings absent). With respect to variant interactions, D is dominant over nd1 and nd2, nd1 is dominant over nd2.