Ever wondered why your cat's coat looks the way it does? Understanding the science behind these coat characteristics can help us appreciate the diversity and beauty of our feline friends.
In part one of our series, we explored the basic genetics of feline fur, including the roles of the KIT gene and primary pigments like eumelanin and pheomelanin. We also covered how different genes contribute to a variety of colors and patterns, such as the black (B), orange (O), dilution (D), and white (W) genes, along with the various tabby patterns influenced by the agouti, tabby, and ticked genes.
In part two we continue our journey into the world of feline genetics, uncovering the secrets behind the stunning coat patterns of our beloved cats!
Pointed Coat Patterns
Cats with a mutation at Locus C causes a temperature sensitive form of partial albinism that results in darker colors on the cooler parts of their body, such as the ears, paws, and tail. This genetic type originated in the Siamese, but is now found in other breeds like Birmans, Himalayan, and Ragdoll.
Interestingly, all pointed cats are born white or very light-colored. As they grow, the cooler parts of their bodies develop the darker points. This process usually starts within the first few weeks of life and can take up to a year to fully develop. The final coloration depends on both genetics and environmental factors, such as the temperature where the cat lives.
Burmese cats are not as well-known for their pointed coats as the Siamese, but they do carry a particular variant of the colourpoint gene. However, the effect is more subtle in Burmese cats, leading to a softer, more blended appearance. This results in a cat with a uniform color that darkens slightly at the extremities, giving them a beautiful, gradient-like coat.
The Inhibitor Gene
The inhibitor gene, designated as "I," affects the pigmentation in a cat's fur. When present, this gene inhibits the production of pigment in the hair shaft, leading to lighter or even white hair at the base. This gives the fur a shimmering or silver appearance. Cats without this gene have fully pigmented hairs, resulting in more traditional colors like black, brown, or orange..
When the inhibitor gene is present, it disrupts the normal function of melanocytes. This disruption leads to less pigment being deposited in the base of the hair, resulting in a lighter color at the root while the tip remains darker. This unique pigmentation pattern creates the striking silver or shaded appearance seen in breeds like the British Shorthair, Persian, and Somali.
The presence of the inhibitor gene can manifest in different ways:
1. Silver Tabbies: These cats have a silvery base coat with darker tabby markings. The inhibitor gene lightens the background color, making the tabby patterns stand out sharply.
2. Smoke Cats: Smoke cats have solid-colored fur that appears dark but reveals a lighter, almost white undercoat when the fur is parted. This gives them a mystical, smoky appearance.
3. Shaded Cats: In shaded cats, the inhibitor gene creates a more gradual transition from light to dark along each hair. These cats often look like they have a light mist over their coat.
Birman Gloving
This is another variant in the KIT gene. Two copies of this variant are required for the characteristic white gloves seen in the Birman cat as part of their breed standard. The "mitted" Ragdoll also has white gloves and it can be difficult to tell these two breeds apart, but the Ragdolls will also have a white stripe from the chin along the belly, whereas Birmans do not. While some mitted Ragdolls do carry the Birman white gloving mutation, this trait is not universal among them, indicating that another genetic mechanism is at play in these cats.
There's obviouly more to a cat's coat than just colour. In our next post, we'll delve into the genetics of fur type. Why are some cats’ coats long and flowing, while others have short, sleek fur? What about curly-haired or even hairless cats? Join us next time as we uncover the secrets behind the texture and type of feline fur!