Four mutations that produce long-haired coats in domestic cats have been identified in a single gene. Three of the mutations are fairly breed specific, while the fourth is present in all long-haired cat breeds and crossbreds.
Cats with colored 'points' have genetic mutations associated with temperature-sensitive pigment production. Pigment production is reduced in warmer areas of the body, leading to darker pigmentation in the cat's cooler extremities (paws, ears, etc.)
The agouti signaling protein interacts with the melanocortin 1 receptor to switch between black and red pigments, creating a banding pattern in individual hairs. Mutations in the agouti signaling protein gene (ASIP) prevent this switch from occurring, resulting in hairs of uniform color.
The Devon Rex breed produces a curly coat and the Sphynx breed is nearly hairless. The nearly hairless coat of the Sphynx breed is recessive to normal coat, and the curly coat of the Devon Rex breed is recessive to the hairless Sphynx coat.