When discussing colorpoint cats, breeds such as the Siamese and Ragdoll often come to mind, recognized for their striking dark faces, ears, and limbs. However, the golden British Shorthair with colorpoint markings is another fascinating example of this genetic phenomenon. Unlike the classic golden British Shorthair, these cats exhibit a predominantly white body with golden and black tones concentrated on the face, ears, and extremities. This distinctive appearance results from the influence of the colorpoint gene, which plays a pivotal role in producing such patterns. But what exactly is the colorpoint gene, and where does it originate? This article explores these questions in detail.
1. What is Colorpoint?
Colorpoint is not a coat color in itself but a type of albinism gene that can overlay any coat color, controlling pigmentation based on body temperature. This gene is temperature-sensitive, meaning it inhibits pigment production in warmer areas of the body. Consequently, areas closer to the core, such as the torso, tend to remain white, while cooler extremities like the face, ears, tail, and legs display darker pigmentation.
Age also influences the expression of the colorpoint gene. Young cats often exhibit a lighter appearance, but as they age, their body temperature may decrease slightly, allowing previously suppressed pigments to emerge. Thus, older colorpoint cats often display a gradual intensification of their markings.
2. The Origins of the Colorpoint Gene
The colorpoint gene manifests in several variations, with the Siamese and Burmese types being the most well-known. The Siamese colorpoint gene (denoted as cs) originates from the ancient Siamese cat breed of Southeast Asia (modern-day Thailand), while the Burmese colorpoint gene (cb) traces back to the Burmese cat, another historic breed from Southeast Asia (Myanmar).
There are three alleles of the colorpoint gene:
• C: Wild type, non-colorpoint.
• cb: Burmese colorpoint.
• cs: Siamese colorpoint.
The dominance hierarchy among these alleles is as follows: C > cb = cs. Interestingly, cb and cs exhibit a co-dominant relationship. This means cats with a genotype of cb/cs display an intermediate phenotype known as “mink,” characterized by a subtle blend of Siamese and Burmese colorpoint features.
Here are the phenotypic outcomes based on genotype:
• C/C, C/cs, or C/cb: Full-colored cats with no colorpoint expression.
• cb/cb: Burmese colorpoint, transmitting the trait to all offspring.
• cs/cs: Siamese colorpoint, transmitting the trait to all offspring.
• cb/cs: Mink colorpoint, displaying intermediate coloration.
3. The Impact of Colorpoint on Eye Color
While blue-eyed white cats are often associated with a risk of deafness, colorpoint cats with blue eyes do not share this concern. This is because the colorpoint gene represents a mild form of albinism, which alters eye color without affecting auditory function.
Interestingly, not all colorpoint cats have blue eyes. Eye color varies across the three types of colorpoint:
• cs/cs (Siamese type): Blue eyes due to the strongest inhibition of melanin production in the iris.
• cb/cb (Burmese type): Yellow or green eyes, as melanin suppression is less pronounced.
• cb/cs (Mink type): Aquamarine eyes, a striking blend of blue and green.
The variation in eye color arises from differences in melanin levels within the iris. Lower melanin levels result in blue eyes, while higher levels produce green, yellow, or even copper tones.
Newborn kittens initially have underdeveloped eyes, which appear blue. Their true eye color gradually emerges around 6–7 weeks of age and reaches full maturity by 3–4 months.
The golden British Shorthair with colorpoint markings showcases the intricate interplay of genetics and environmental factors. Understanding the origins and expressions of the colorpoint gene not only highlights the diversity within feline breeds but also enhances our appreciation for the unique beauty of these cats.
