Feline polycystic kidney disease (PKD1) is a heritable form of polycystic kidney disease commonly seen in Persians and cats with Persian ancestry. Affected cats develop cysts on their kidneys, which often leads to renal failure at a later stage.
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 Selkirk Rex breed has curled hair that can be short or long. A single copy of the variant that causes the Selkirk Rex coat produces wavy hair, and two copies produce a tighter curl as well as a slender body type with long ears.