Cat coat genetics determine the colouration, pattern, length, and texture of feline fur. The variations among cat coats are physical properties and should not be confused with cat breeds. A cat may display the coat of a certain breed without actually being that breed. For example, a Neva Masquerade (Siberian colourpoint) could wear point colouration, the coat typically associated with a Siamese.
Solid colours
Eumelanin and phaeomelanin Eumelanin The browning gene B/b/bl codes for TYRP1 (), an enzyme involved in the metabolic pathway for eumelanin pigment production. The dominant form, B, will produce black eumelanin. It has two recessive variants, b (chocolate) and bl (cinnamon), with bl being recessive to both B and b. Chocolate is a rich dark brown colour, and is referred to as chestnut in some breeds. Cinnamon is a light brown which may be a reddish colour.
Sex-linked red
The sex-linked red "Orange" locus, O/o, determines whether a cat will produce phaeomelanin. In cats with orange fur, phaeomelanin (red pigment) completely replaces eumelanin (black or brown pigment). This gene is located on the X chromosome. The orange allele is O, and non-orange is o. Males are typically only orange or non-orange due to only having one X chromosome. Since females have two X chromosomes, they have two alleles of this gene. OO results in orange fur, oo results in fur without any orange (black, brown, etc.), and Oo results in a tortoiseshell cat, in which some parts of the fur are orange and other areas non-orange. One in three thousand tortoiseshell cats are male, making the combination possible but rare - however, due to the nature of their genetics, male tortoiseshells often exhibit chromosomal abnormalities. In one study, less than a third of male tortoiseshells had a simple XXY Klinefelter's karyotype, slightly more than a third were complicated XXY mosaics, and about a third had no XXY component at all (XX/XY or XY/XY mosaics).
The coat colour commonly referred to as "orange" is scientifically known as red. Other common names include yellow, ginger, and marmalade. Red show cats have a deep orange colour, but it can also present as a yellow or light ginger colour. Unidentified "rufousing polygenes" are theorised to be the reason for this variance. Orange is epistatic to non-agouti, so all red cats are tabbies. "Solid" red show cats are usually low contrast ticked tabbies.
The identity of the gene at the Orange locus was narrowed down to a 3.5 Mb stretch on the X chromosome in 2009. In 2024 it was discovered that the dominant orange colour associated with the Orange locus is the result of a genomic deletion in a regulatory region of ARHGAP36, a Rho GTPase activating protein. The deletion results in a 13-fold increase in expression of the protein in melanocytes.
Dilution
The Dense pigment gene, D/d, codes for melanophilin (MLPH; ), a protein involved in the transportation and deposition of pigment into a growing hair. When a cat has two of the recessive d alleles (Maltese dilution), black fur becomes "blue" (appearing grey), chocolate fur becomes "lilac" (appearing light, almost greyish brown-lavender), cinnamon fur becomes "fawn", and red fur becomes "cream". Similar to red cats, all cream cats are tabbies. The d allele is a single-base deletion that truncates the protein. If the cat has d/d genes, the coat is diluted. If the genes are D/D or D/d, the coat will be unaffected.
+Overview of dilutions in cat coat coloursBasic colourDilutionDilute modifier, double dilutionBlack ("brown")Blue ("grey")Caramel, blue-based caramel (UK)ChocolateLilacTaupe, lilac-based caramel (UK)CinnamonFawnFawn-based caramel (UK)Red ("orange")CreamApricotAmberLight amberUnknownWhiteN/AN/A
Other genes
Barrington Brown is a recessive browning gene that dilutes black to mahogany, brown to light brown and chocolate to pale coffee. It is different from the browning gene and has only been observed in laboratory cats. The Dilution modifier gene, Dm, "caramelises" the dilute colours as a dominant trait. The existence of this phenomenon as a discrete gene is a controversial subject among feline enthusiasts. Amber, a mutation at the extension locus E/e (the melanocortin 1 receptor; MC1R) changes black pigment to amber or light amber, similar in appearance to red and cream. Kittens are born dark but lighten up as they age. Paws and nose still exhibit the original undiluted colour in contrast to other diluted colours, where paws and nose have the diluted colour. This phenomenon was first identified in Norwegian Forest Cats. Another recessive mutation at extension was discovered which causes the "russet" colour in Burmese cats. It is symbolised as er. Like amber cats, russet cats lighten as they age. A modifying factor has also been hypothesised in shaded silver and chinchilla Persians whose fur turns pale golden in adulthood, due to low levels of phaeomelanin production. These cats resemble shaded or tipped goldens, but are genetically shaded or tipped silvers. This is probably related to the phenomenon known as "tarnishing" in silvers.
Tabbies
Tabby cats have a range of variegated and blotched coats, consisting of a dark pattern on a lighter background. This variety is derived from the interplay of multiple genes and resulting phenotypes. Most tabbies feature thin dark markings on the face, including the 'M' on the forehead and an eyeliner effect, pigmented lips and paws, and a pink nose outlined in darker pigment. The following tabby coat patterns are all naturally found in the domestic cat: Mackerel: Thin, dark stripes (sometimes called "tiger stripes"). Blotched/Classic: Thicker bands or whorls of dark pigment. Spotted: Broken bands that look more like individual spots. The flanks only contain spots, no stripes. Ticked: No distinct stripes, spots, or blotches on the body—though some may be visible on the legs, face, and tail.
Agouti
The agouti factor determines the "background" of the tabby coat, which consists of hairs that are banded with dark eumelanin and lighter phaeomelanin along the length of the hair shaft. The Agouti gene, with its dominant A allele and recessive a allele, controls the coding for agouti signalling protein (ASIP; ). The wild-type dominant A causes the banding and thus an overall lightening effect on the hair, while the recessive non-agouti or "hypermelanistic" allele a does not initiate this shift in the pigmentation pathway. As a result, homozygous aa have pigment production throughout the entire growth cycle of the hair and therefore along its full length. These homozygotes are solidly dark throughout, which obscures the appearance of the characteristic dark tabby markings—sometimes a suggestion of the underlying pattern, called "ghost striping", can be seen, especially on kittens and on adults in bright slanted light, in smokes, and sometimes on the forehead, legs, tail or elsewhere.
A major exception to the solid masking of the tabby pattern exists, as the O allele of the O/o locus is epistatic over the aa genotype. That is, in red or cream coloured cats, tabby marking is displayed regardless of the genotype at the agouti locus. However, some red and most cream tabbies do have a fainter pattern when lacking an agouti allele, indicating that the aa genotype does still have a faint effect even if it does not induce complete masking. The mechanism of this process is unknown.
An example of the Agouti gene can be seen in Bengal cats, which are a hybrid between Asian leopard cats and domestic cats. The breed sports the hybrid 'charcoal' pattern, a pseudomelanistic marking which has a characteristic dark face marking, the "mask", and a broad dorsal stripe down its back, the "cape". According to Gershoney et al., the charcoal mask is indicated to be the result of a heterozygote of APbe/a. The relationships between the different agouti alleles is not fully understood. More research is required to determine the inheritance modes for charcoal.
Tabby markings The Tabby locus on chromosome A1 accounts for most tabby patterns seen in domestic cats, including those patterns seen in most breeds. The dominant allele TaM produces mackerel tabbies, and the recessive Tab produce classic ('blotched') tabbies. The gene responsible for this differential patterning had been identified as transmembrane aminopeptidase Q (Taqpep, ). The gene name Taqpep has later been replaced by laeverin with symbol LVRN. A threonine to asparagine substitution at residue 139 (T139N) in this protein is responsible for producing the tabby phenotype in domestic cats. In cheetahs, a base pair insertion into exon 20 of the protein replaces the 16 C-terminal residues with 109 new ones (N977Kfs110), generating the king cheetah coat variant.
The wild-type (in African wildcats) is the mackerel tabby (stripes look like thin fishbones and may break up into bars or spots). The most common variant is the classic tabby pattern (broad bands, whorls, and spirals of dark colour on pale background usually with bulls-eye or oyster pattern on flank). Spotted tabbies have their stripes broken up into spots, which may be arranged vertically or horizontally. A 2010 study suggests that spotted coats are caused by the modification of mackerel stripes, and may cause varying phenotypes such as "broken mackerel" tabbies via multiple loci. If the genotype is Sp/Sp or Sp/sp the tabby coat will be spotted or broken. If it is an sp/sp genotype, the tabby pattern will remain either mackerel or blotched. This gene has no effect on cats with a ticked coat.
Ticked tabby The Ticked (Ti) locus on chromosome B1 controls the generation of "ticked coats", agouti coats with virtually no stripes or bars. Ticked tabbies are rare in the random-bred population outside Asia, but fixed in certain breeds such as the Abyssinian and Singapura. TiA is the dominant allele that produces ticked coats; Ti+ is the recessive one. The causative gene for ticked tabby markings is Dickkopf-related protein 4 (DKK4). Both a cysteine to tyrosine substitution at residue 63 (C63Y) and an alanine to valine substitution at residue 18 (A18V) result in decreased DKK4, which is associated with ticking. Both variants are present in the Abyssinian breed, and the A18V variant is found in the Burmese breed. Stripes often remain to some extent on the face, tail, legs, and sometimes the chest ("bleeding through"). Traditionally, this has been thought to happen in heterozygotes (TiATi+) but be nearly or completely nonexistent in homozygotes (TiATiA). The ticked tabby allele is epistatic to and therefore completely (or mostly) masks all the other tabby alleles, "hiding" the patterns they would otherwise express.
It was once thought that TiA was an allele of the Tabby gene, called Ta, dominant to all other alleles at the locus.
Other genes
Other genes (pattern modifier genes) are theorised to be responsible for creating various type of spotting patterns, many of which are variations on a basic mackerel or classic pattern. There are also hypothetical factors which affect the timing and frequency of the agouti shift, affecting agouti band width and the number and quality of alternating bands of eumelanin and phaeomelanin on individual hairs. There is a gene not yet identified, but believed to be related to the agouti gene in the Chausie breed that produces silver-tipped black fur similar to Abyssinian ticked fur, known as "grizzled". This phenomenon is purported to have been inherited from the hybridisation of the domestic cat to the jungle cat (Felis chaus). The rosette tabby pattern is a pattern similar to that of a leopard, where rosette spots are spread over the body. The pattern is found in hybrid cat breeds, such as the Bengal and Safari.