There are several different modifying genes which can have an effect on coat color.
PangareCharacterized by their lightened soft spots mealy affects most base colors and is commonly found on a variety of breeds worldwide.
SootySooty presents black hairs mixed in with the body coat along the topline. Most commonly found in chestnuts, bays and palominos.
FlaxenFlaxen affects the mane and tail hairs of a chestnut base, diluting them to flaxen or pure white. Some breeds are exclusively flaxen.