White patterns are caused by many different genes, and combinations of these may result in more extreme expressions. A few examples are: frame, tobiano, sabino, splashed white and dominant white. White markings are usually included in the list.
Patterns can range from a few white hairs on the coat, to a completely white body, often with pink skin. The edges of the patterns can be round, straight, cornered or include vague ‘ticking’ / ‘roaning’.
White patterns can appear on any coat colour, whether diluted, modified or neither. Grey is no exception to this. Remember, grey is a modifier which turns a coat grey as the horse ages. White patterns are white hairs which are often present from birth (though may increase in number later on). As a horse turns grey, the white patterns may become nearly invisible, but they are still there (as evidenced by the pink skin). The grey only masks the white.