There are four base horse coat colors: black, brown, bay, and chestnut. Additional coat colors result from genetic modifications and dilutions of these base colors. Dilutions can produce colors like palomino, buckskin, and dun. The dun gene produces four dun categories with distinctive dorsal stripes, masks and leg barring. Other coat colors and patterns include grey, roan, tobiano and overo spotting. Horse coat colors can be complex and more research is still needed to fully understand all the genetic factors that produce the wide variety of coat colors and patterns seen.