Acromelanism

Colourpoint patterns are where the extremities (paws, face, ears and tail) of the animal are coloured differently compared to the rest of the body. The areas with different colour may be referred as 'points' or being 'pointed'.^[3] Colour can spread to the rest of the body, but is concentrated on the extremities.

Colourpoint patterns occur due to acromelanism, which is a type of partial albinism where pigmentation is affected by temperature. Cold temperatures trigger pigment development while warm temperatures decrease pigment development. The extremities are colder than the rest of the body which is why they darken.

The C locus in mammals is most often associated with the TYR gene, which controls the production of the tyrosinase enzyme that produces melanin.^[4]

The colour point allele is at the C locus, where some forms of typical albinism are also located. Point is recessive for all animals. In cats, two copies of c^s, one from each parent, are needed for points to be expressed.

Point colouration in domestic cats originated in random-bred populations in Southeast Asia. Although the pattern is most commonly associated with the Siamese breed, the vast majority of colourpoint cats worldwide are not descended from these modern pedigree Siamese (or Thai) cats and are domestic shorthairs or longhairs without any Siamese ancestry. The pattern predates the development of formal cat breeds, which only started around 1875, and was dispersed globally centuries before through ship cats during the era of maritime exploration. Coat colour alone does not reliably indicate recent descent from either Southeast Asia or any specific breed, as the recessive colourpoint allele can appear in otherwise fully pigmented litters. It only indicates that both parent cats carry a colourpoint gene.

Colourpoint is a form of partial albinism resulting from a mutation of tyrosinase (TYR), an enzyme involved with melanin production. There exist multiple allele variants of the colourpoint; as of 2026, the known variants are c^s (point), c^b (sepia), c^m (mocha), and the combination of c^sc^b (mink) is also found.^[5][6]

The mutated enzyme is thermolabile (temperature-dependent); it fails to work at normal body temperatures, but becomes active in cooler areas of the skin.^[7][3] As a result, dark pigment is limited to the coldest areas of the body, that is, the extremities; the nose, ears, feet, and tail.^[3][5] Pointed c^sc^s kittens are born solid-white, due to the warmth of uterus. As the kitten ages, the cooler areas darken while warmer areas remain cream to white in colour. Colourpoints can usually be observed at four weeks.^[3]

As the expression of the gene responsible for the pointed pattern is regulated by temperature, pointed cats who live in cooler environments often show increased darkening of their fur relative to cats who live in warmer climates; in some extreme cases the entire coat will darken. Shaving a cat can also change the colour of the coat. Conditions that affect the temperature of the animal can change the colour too, e.g. pyrexia can inactivate tyrosinase and result in new growth being uncoloured and obesity may result in the whole body turning dark due to the decreased skin temperature.^[3]

Because of the pigment restriction caused by the temperature-sensitive tyrosinase, pointed cats' eyes are always shades of blue because the blue layer in the eye common to all cats is not covered by another colour. The back of the eye also lacks pigment, giving colourpoint cats' pupils a red and silver reflection in the dark, unlike a normally pigmented cat's shining silver-green or -blue.

Strabismus is genetically linked to the colourpoint allele and is generally harmless.

• Comparison of different black (seal, sable) cats
• 
  Black full colour
• 
  Black sepia Burmese
• 
  Black mink Tonkinese
• 
  Black point Siamese
• 
  Black mocha
• 
  Black albino
• 
  Black blotched tabby (US: lynx) point domestic shorthair
• 
  Black tortoiseshell point cat

Above an overview illustrating the effects of the C locus allelic series. The gradient in black pigment intensity represents the relative amount of pigmentation expressed, rather than the type or specific colour of pigment; all cats are black. The C locus influences the expression of both eumelanin and phaeomelanin. In colourpoint cats, the extremities (face, ears, paws and tail) may appear uniformly coloured or may exhibit additional patterning, such as tabby striping (US: “lynx point”) or tortoiseshell in individuals, depending on the genotype at other genetic loci.^[6]

A number of informal nicknames for point colourations in English-language usage differ from formal genetic terminology, which can vary by dialect, cat registry, and community. Black is also known as 'seal' (for point, and for sepia in New Zealand), 'sable' (for sepia and mink in the US) or 'brown' (for sepia in the UK and Australia), red as 'flame point', chocolate as 'champagne' (for sepia and mink in the US), and lilac as 'platinum' (for sepia and mink in the US) or 'frost'.

Rarely, dogs (Canis familiaris) are documented with point colouration or acromelansim.^[9] Recent documented evidence about acromelanism in dogs has only existed since 2017, when the first colourpoint dachshund was reported in the Czech Republic. More dogs have appeared since then, with the majority from the Eastern Eurasian region and Canada. Genotyping the aforementioned dachshund revealed a mutation in the tyrosinase gene that results in a recessive colourpoint allele.^[10][11] A second tyrosinase variant is responsible for the colourpoint coat seen in a family of rescue dogs.^[12]