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. 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).
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.
Other genes tabby pattern in a
Bengal. • 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. • The
inhibited pigment gene,
I/i. The dominant allele (I) produces
tipped hairs that are fully coloured only at the tip and have a white base. This allele appears to interact with other genes to produce various degrees of tipping, ranging from deeply tipped silver tabby to lightly tipped shaded silver and chinchilla silver. The inhibitor gene interacts with the non-agouti genotype (I-aa) to produce the colour known as
smoke. The homozygous recessive genotype when combined with the agouti gene (iiA-), produces tabby colouration, which can vary along a spectrum ranging from a deeply patterned brown tabby, to a lighter "golden tabby", to the very lightly coloured shaded or chinchilla golden colours. Red and cream cats with the inhibitor gene (I-O-) are commonly called "
cameo". == Tortoiseshells ==