Copal Coat (MC1R gene, Kurilian Bobtail)

The "copal" trait in Kurilian Bobtail cats is an apricot red coloration that develops with age and is caused by a variant in the MC1R gene, also known as the extension locus (E locus).

Definition

Copal color is a shade of red coat identified in Kurilian Bobtail cats. This color can vary from birth to adulthood, starting with a warm reddish hue that gradually becomes lighter and resembles the X-linked orange coloration. This coloration is caused by a mutation in the MC1R (melanocortin 1 receptor) protein, which regulates the amount of eumelanin (dark pigment) and pheomelanin (light pigment). Activation of MC1R leads to the formation of dark coat, while inactivation of MC1R results in a lighter coat.

Genetic basis

The e^c allele is responsible for the copal coat in the Kurilian Bobtail breed and is due to a c.640_669del deletion in the MC1R gene. This variant follows an autosomal recessive mode of inheritance, which means that two copies of the variant are required to express this coat coloration. The presence of a single copy does not produce the copal phenotype, but it can be transmitted to offspring with a 50% probability.

Other relevant information

An interesting fact about the c.640_669del mutation in the MC1R gene in the Kurilian Bobtail is that this same mutation can cause a similar effect in other animal species, including horses and dogs. In these species, the mutation in MC1R also leads to red or yellow coloration of the coat.

Bibliography

Abitbol M, Gache V. Copal, a new MC1R allele in the domestic cat. Anim Genet. 2019 Oct;50(5):553-554.