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Cinnamon and dilution genes

Pigmentation

The colours in hair, skin and eyes, are caused by the presence of melanin. Melanin is deposited in hair shafts, in the form of microscopic granules which can vary in shape, size and arrangement, which gives a variety of colours. There are two chemically different kinds of melanin: eumelanin and phaeomelanin. Eumelanin granules are thought to be spherical in shape, and absorb almost all light, giving black pigmentation. Phaeomelanin granules, are thought to be elongated in shape, and reflect light, in the red/orange-/yellow range. Several genes can cause variation in the density of the the melanin granules, so other colours can be produced. The most variation is found in the black-based (eumelanistic) colours.

Mutations of the gene for Black give rise to Chocolate and Cinnamon. These colours are thought to be due to a smaller number of eumelanin granules in the hair shaft. These are alleles at the (B) locus; Chocolate is recessive to Black, and Cinnamon is recessive to Chocolate.

A mutation of the gene for Dense colouration produces Blue, Lilac, and Fawn. These colours are due to clustering of the particles of pigment in the hair shaft. This is called dilution. Blue is the dilute form of Black; Lilac is the dilute form of Chocolate, Fawn is the dilute form of Cinnamon.

Dilution is a mutation at the (D) locus - dilution is recessive to dense colouration.

Cinnamon is like Seal and Chocolate a fully pigmented (dark) Colour which is based on the storage of the dark eumelanin pigment granules in hair (coat) and skin. It is determinated from the same gene locus as Seal and Chocolate and is member of the 'Black' series.

In genetic terms Cinnamon is also called light brown (bl). Cinnamon has also nothing in common with the colour RED.

Cinnamon Gene

Cinnamon is recessive against Seal and Chocolate. A gene is called recessive when it is covered by a dominant gene. These genes can be carried over generations 'under cover' and given to the next generation without being noticed. Recessive genes only take effect when both parents have given them to the next generation.

Homozygote and Heterozygote

A cat is geneticly homozygote when it's appearance is the same as the genetic basics. This cat has two similar alleles at a gene locus. This means that no other characteristics are carried 'under cover'.

A heterozygote cat in genetic terms is a cat that is carrying the not shown genetic information, because of the dominant genes. It has two dissimilar alleles at a gene locus. It is not possible to draw a genetic conclusion from the appearance. This means that recessive characteristics are 'hidden'. The characteristics can only be defined when mating these carriers to each other. Only a pedigree certificate can identify carriers.

What does this mean for breeding

A mating, between two homozygote Cinnamon cats can only lead to Cinnamon kittens born. Seal, Chocolate etc., kittens cannot be born. If the Cinnamon cats are heterozygote (carrying dilution), then Cinnamon and Fawn kittens can appear in the same litter.

Seal, Chocolate, Blue, Lilac cats, can carry the gene for Cinnamon in their gene pool (cinnamon carriers). If mated to another Cinnamon carrier, then Cinnamon kittens can result.

The gene for dilution is recessive like the gene for Cinnamon. A crossing between cats with a cinnamon gene 'bl' and carrying the dilution gene 'd' can lead to a fawn kitten. The colour Fawn is the dilution of Cinnamon.

A crossing between 2 Fawn cats can only result in Fawn kitten.

To get Cinnamon and Fawn kittens both parents need to be Cinnamon or Cinnamon carriers and both need to carry the dilute gene - otherwise only Cinnamon kittens are born, but should carry the dilute colour gene.

Seal and Chocolate cats, carrying the genetic information for Cinnamon and Dilution can also lead to Cinnamon and Fawn kittens.

If Seal and Chocolate cats carry Cinnamon and no dilute gene, only Cinnamon kittens are possible.