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The Genetics of Cat Colours and Coat Types: Unlocking the Mystery of Feline Fur (Part 3)

Short versus Long-haired cats:

Have you ever wondered why some cats have long, flowing fur while others have short, sleek coats? The secret lies in their genes, specifically the Fibroblast Growth Factor 5 (FGF5) gene. Let's explore what the FGF5 gene is, how it affects your cat’s coat, and why it's important for cat owners to understand.

What is the FGF5 Gene?

The FGF5 gene plays a crucial role in regulating hair growth in cats. This gene helps control the length of the hair growth cycle. When the FGF5 gene functions normally, it signals the end of the hair growth phase, leading to shorter fur. However, a mutation in this gene can extend the growth phase, resulting in longer hair.

How Does the FGF5 Gene Affect Your Cat’s Coat?

Short-Haired Breeds: 

Cats with a normal FGF5 gene typically have shorter coats. Breeds like the Siamese, British Shorthair, and Bengal fall into this category. While they generally require less grooming than their long-haired counterparts, regular brushing can still help reduce shedding and keep their coat healthy.

Long-Haired Breeds:

If your cat has a mutation in the FGF5 gene, they are likely to have a long, luxurious coat. This is common in breeds such as Persians, Maine Coons, and Ragdolls. These cats require more grooming to prevent mats and tangles. Regular brushing is essential to keep their fur in top condition and to avoid any discomfort from knots.

A British Longhair and a British Shorthair cat
A British Longhair and a British Shorthair cat

Rex Coat Patterns

These curly-coated felines have a distinct charm, and their genetics play a fascinating role in creating those signature waves and curls. Let’s dive into the world of rex coat patterns and uncover the genetic secrets behind them.

What is a Rex Coat?

Rex coats are characterised by soft, curly, or wavy fur, which can vary in texture and length. Unlike the typical straight-haired cats, rex-coated cats have a unique mutation that affects the structure of their hair follicles, resulting in their distinctive coats. There are several breeds known for their rex coats, including the Cornish Rex, Devon Rex, and Selkirk Rex, each with its own unique genetic makeup.

The Genetic Basis of Rex Coats

The curly coats of rex cats are the result of specific genetic mutations. Here’s a look at the primary genes involved:

Cornish Rex (re gene):

The Cornish Rex’s wavy coat is caused by a mutation in the keratin 71 protein (KRT71) gene, commonly referred to as the "re" gene. This mutation leads to a lack of guard hairs (the long, protective outer layer of fur), leaving only the softer, curly undercoat. This gene is recessive, meaning a cat must inherit two copies of the mutated gene (one from each parent) to display the rex coat.

Devon Rex (se gene):

The Devon Rex also owes its unique coat to a mutation in the KRT71 gene, but it’s a different mutation than the one seen in Cornish Rexes. This mutation, called the "se" gene, similarly affects hair follicle structure, leading to short, soft, and curly fur. Like the Cornish Rex, the Devon Rex needs two copies of this recessive gene to exhibit its characteristic coat.

Selkirk Rex (hr gene):

The Selkirk Rex’s plush, curly coat comes from a dominant mutation in the same KRT71 gene, known as the "hr" gene. Unlike the Cornish and Devon Rexes, Selkirk Rexes only need one copy of this dominant gene to display their curly fur. This makes the Selkirk Rex unique among the rex-coated breeds.

The Genetics of Hairless Cats

Hairless cats, such as the iconic Sphynx, are known for their distinct lack of fur and captivating looks. But have you ever wondered what makes these felines hairless? Like the rex breeds, this mutation occurs in the KRT71 gene. When the KRT71 gene is altered in a particular way, it disrupts the normal development of hair follicles, resulting in little to no hair growth.

A Sphynx cat
A Sphynx cat

Other Hairless Breeds

The Sphynx is not the only hairless cat breed. Other breeds, like the Donskoy and Peterbald, also exhibit hairlessness but through different genetic mutations.

The Wonder of Genetics

The genetics of cat coat colors and fur types is a complex but captivating field that reveals the intricate dance of genes and inheritance. Each cat’s coat tells a genetic story, from the simplest solid colour to the most intricate pattern, and from the shortest hair to the most luxurious long fur. Next time you admire your cat’s beautiful fur, you’ll have a deeper appreciation for the genetic magic that created it.


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