Palomino results from a single copy of the cream dilution gene acting on a chestnut base coat. Palomino is a horse coat color characterized by a golden body with a white or cream mane and tail. The shade of the body coat can vary widely, ranging from light cream to rich, dark gold. Unless influenced by other unrelated genes, palomino horses typically have dark skin and typical eye color is brown, although some individuals may have lighter brown or amber eyes. The cream gene is inherited in an incompletely dominant manner. A palomino carries one copy of the cream gene and can pass it to about 50% of its offspring on average. When two single cream carriers are bred together, about 25% of foals inherit no copy of the gene, 50% inherit one copy, and 25% inherit two copies. Horses that inherit two copies of the cream gene are known as double cream dilutes—cremello, perlino, or smoky cream—which have very pale coats and typically blue eyes.

Non-KIT white spotting refers to depigmentation patterns in horses caused by mutations in genes other than KIT, most commonly MITF or EDNRB. These mutations affect the development and migration of melanocytes during embryonic development, preventing them from reaching certain areas of the skin and resulting in distinctive white markings. Non-KIT white spotting patterns are often associated with characteristic phenotypes that can vary widely in expression, ranging from minimal white markings to large white areas covering significant portions of the body. Some non-KIT white spotting patterns may also influence eye color. Non-KIT white spotting mutations are typically inherited as autosomal dominant traits, meaning only one copy of the mutation is required for expression. However, expression can vary significantly between individuals, and some mutations may be lethal in the homozygous state.

Frame overo is caused by a mutation in the EDNRB gene. Frame overos have sharply defined, irregular, horizontally oriented white patches. Expression of the frame overo pattern can vary widely. The head is often white or bald-faced, and blue eyes are not uncommon. There are a few frame overo lines in the Thoroughbred breed. Frame overo is autosomal dominant. All adult frame overo horses are heterozygous, carrying only one copy of the gene, and have a 50% chance of passing it down to their offspring. Homozygotes develop Lethal White Syndrome and die within few days after birth as their intestines don’t develop the nerves needed to move food. Lethal White Syndrome can be completely eliminated by testing all mares and stallions and is 100% preventable through education and responsible breeding. Frame overo gene can be carried without obvious large markings, so carriers cannot always be identified visually. Therefore, genetic testing is essential.