GENE LOCI IN CATS

This lists the different loci and combinations of alleles, including a few hypothetical or unconfirmed genes. In the case of the posited genes listed, there has been sufficient breeding data or study of cats with the trait(s) for the genes to be statistically likely.

CLASSIC BLACK/BROWN

This is a gene series with the order of dominance: Black/Brown > Chocolate > Cinnamon. Browning genes code for tyrosinase related protein-1 (TYRP1) , an enzyme involved in the metabolic pathway for eumelanin pigment production. The dominant form, B, produces black color. Recessive variants are b (chocolate) and bl (cinnamon/light brown).

B - Black/Brown Locus

Genotype

Description

Phenotype

B/B

Homozygous - Black/Brown

Black/Brown

B/b

Heterozygous - Black/Brown - carrying Chocolate

Black

B/bl

Heterozygous - Black/Brown - carrying Cinnamon

Black

b/b

Homozygous - Chocolate

Chocolate

bl/bl

Homozygous - Cinnamon

Cinnamon - reddish chocolate

b/bl

Heterozygous - Chocolate - carrying Cinnamon

Chocolate

 

"BARRINGTON BROWN"

Don Shaw's "Barrington Brown" may be a further recessive brown colour. It was observed in a colony of laboratory cats, none of which left the laboratory. Some breeders erroneously believed it to have been the dilute modifier (caramel) gene. However, the Barrington Brown homozygotes were different in colour to caramel cats. In the homozygous form, Barrington Brown had an additive effect on the other colours (some suggest cats with one copy of the gene and cats with two copies looked different, but a cat with only one copy of the gene shouldn't show any effect).

ba - Barrington Brown Locus (unverified)

Genotype

Description

Phenotype

Ba/Ba

Homozygous - Non Barrington Brown

Cat unaffected - i.e. Black/Brown/Chocolate etc

Ba/ba

Heterozygous - Non Barrington Brown - carrying Barrington Brown

Cat unaffected - i.e. Black/Brown/Chocolate etc

ba/ba

Homozygous - Barrington Brown -liberty of renaming

Mahogany Brown/Light Brown/milk coffee in colour

 

EPISTATIC RED

This is a sex-linked trait carried on the X chromosome. It causes phaeomelanin (orange pigment) to completely replace eumelanin (black or brown pigment). Red can also be modified in the following fashion:
O + d/d (homozygous for dilute colour) = Cream
O + d/d + Dm (dilute modifier) = Apricot

O - Red Locus (sex-linked epistatic)

Genotype

Description

Phenotype

XO/XO

Homozygous - Red Female

Red female

XO/Xo

Heterozygous - Tortie

Female, Red intermixed with a non-red colour i.e.. black tortie, chocolate tortie

Xo/Xo

Homozygous - Non-red female

Female, not red, not tortie

XO/Y

Red Male

Red male

XoY

Non-red male

Male, not red

XXY

Klinefelter mosaic male

Sterile tortie male (red + a non-red colour)

XY/XY, XX/XY

Chimera mosaic male

Fertile tortie male (red + a non-red colour), passes on either red or non-red to offspring

 

COLOURPOINT OR HIMALAYAN PATTERN (ALBINO SERIES)

Colourpoint is a series of alleles (also known as temperature-sensitive albino) due to 2 mutations in the Tyrosinase (TYR) gene. The order of dominance is C > cb/cs >  ca > c. The alleles cs and cb are co-dominant to each other and expression of these is temperature sensitive with the pigmentation being restricted to the cooler extremities of the body: muzzle, ears, tail and legs. Colourpoint cats in colder regions generally have darker body colour and more extensive points while those in warmer regions generally have paler bodies and smaller coloured areas. This can also be demonstrated by bandaging a cat's limb while it is moulting - the newly grown fur will be paler because the bandaged area is relatively warm. Colourpoint expression is also age-related, with older cats tending to be darker than younger cats.

True albino cats (absence of pigment) are rare because the more dominant alleles must be absent in order for albino to show up. Almost all blue-eyed white cats are due to the epistatic white gene or the white spotting gene which mask pigment.

The C gene codes for the enzyme tyrosinase, the first step in pigment production.

C - Colour Restriction Locus

Genotype

Description

Phenotype

C/C

Homozygous - Solid Coloured

Solid colour

C/c

Heterozygous - Solid Coloured carrying red eyed albino

Solid colour

C/ca

Heterozygous -Solid Coloured carrying blue eyed albino

Solid colour

C/cs

Heterozygous - Solid Coloured carrying colour point

Solid colour

C/cb

Heterozygous - Solid Coloured carrying sepia

Solid colour

c/c

Homozygous - Pink eyed Albino (recessive white)

Unpigmented (white) with Pink eyes

ca/ca

Homozygous - Blue eyed Albino (recessive white)

Unpigmented (white) with pale blue eyes

cs/cs

Homozygous - Colourpoint

Colourpoint, Siamese pattern

cb/cb

Homozygous- Sepia

Sepia, Burmese pattern

cb/cs

Heterozygous- Mink (co-dominant Sepia and Colourpoint)

Mink, Tonkinese pattern (intermediate between colourpoint and sepia)

cs/ca

Heterozygous - Bondanese

Colourpoint, Siamese with high contrast

cb/ca

Heterozygous- Sepia & Blue eyed albino

Sepia, Burmese pattern (unverified)

cs/c

Heterozygous Point & Red eyed albino

Sepia, Burmese pattern (unverified)

cb/c

Heterozygous Sepia & Red eyed albino

Sepia, Burmese pattern (unverified)

ca/c

Heterozygous Blue eyed albino & Red eyed Albino

Unpigmented (white) with pale blue eyes (unverified)

 

Breakthrough Tabby Pattern in Colourpoints

Cats born of Siamese parents sometimes have a tabby/spotted pattern breaking through so strongly that the cat appears to be a tabby/spotted Oriental or a tabby/spotted sepia (Burmese) cat. Viewed closely, the pattern colour is heavily ticked on a paler ticked background. This breakthrough pattern is evident from kittenhood and not the same as age-related darkening in Colourpoint cats. It is inherited, possibly due to modifier genes that prevent the colourpoint gene from properly inhibiting the colour/pattern on the normally pale areas of the body.

COLOUR DILUTION & DILUTE MODIFIER

Dense and Dilute colours are due to a simple gene pair (gene: Melanophilin or MLPH). When two dilute alleles are present, it changes the basic (dense) colour to its dilute form e.g. black dilutes to blue, chocolate dilutes to lilac, cinnamon dilutes to fawn, red dilutes to cream. The dominant Dilute Modifier gene only affects dilute colours. Dilute modifier has no effect on Dense colours, but may be carried by dense-colour cats and passed on to offspring and may therefore show up in later generations that also have the two dilute alleles.

D/d, codes for melanophilin, a protein involved in the transportation and deposition of pigment into a growing hair. The dominant form allows denser deposition of pigment.

D - Colour Density/Dilution Locus

Genotype

Description

Phenotype

D/D

Homozygous - Dense pigmentation

Dense (dark) colour, e.g. black, chocolate, cinnamon, red

D/d

Heterozygous - Dense carrying dilution

Dense (dark) colour, e.g. black, chocolate, cinnamon, red

d/d

Heterozygous - Dilute

Dilute colour, e.g. blue, lilac, cinnamon, cream

Dm - Dilute Modifier Locus

Genotype

Description

Phenotype

Dm/Dm

Homozygous - Dilute Modifier

Caramelised dilute colour, no effect on dense colour

Dm/dm

Heterozygous - Dilute Modifier - carrier of non dilute modifier

Caramelised dilute colour, no effect on dense colour

dm/dm

Homozygous - Non-dilute Modifier

No effect

 

EPISTATIC (DOMINANT) WHITE, WHITE SPOTTING, MITTING AND GLOVING GENES 

Epistatic white masks other colour and pattern alleles hence solid white cats may genetically be solid or patterned cats in any colour. The underlying colour will show up in any offspring that don't inherit the dominant epistatic white allele. The white spotting gene creates white markings on a solid or patterned cat. A separate recessive gene "G" has been identified for Birman white gloving. There are hypothetical genes for other white mitted patterns and for the York Chocolate white pattern. There are believed to be genes, as yet unidentified, for the white throat locket and white brisket spots.

The epistatic white gene is associated with developmental defects where melanocytes fail to migrate properly. This can result in one or both blue eyes and in degenerative changes in the succule and cochlea of the ear (resulting in partial or total deafness). The white spotting gene is variable in expression from white locket through to solid white and high grade white spotting can resemble epistatic white, however it is rarely associated with deafness.

Epistatic white prevents migration of pigment-producing cells to the skin during embryologic development. The number of melanocytes are greatly reduced, but not always absent (hence temporary smudges of colour on the heads of some kittens). It is sometimes called dominant white.

The Birman "White Gloving" pattern results from an autosomal (non-sex-linked) recessive mutation in the KIT gene. A cat with two copies of this mutation has gloved white feet. A cat with only one copy will not have gloved feet, but may have white markings due to other, separately inherited, white spotting genes e.g. the hypothetical "mitted" gene. The White Gloving mutation is fixed as a breed trait in Birman cats, therefore Birmans are homozygous for the mutation. Cats with the White Glove mutation are also found in the Ragdoll, Egyptian Mau, Exotic Shorthair, Maine Coon, Manx, Seychellois, Siamese, Siberian, Sphynx and Turkish Van. Testing has found that the Ragdoll "Mitted" pattern is not due to the White Gloving pattern. Because white feet can result from several different mutations, a genetic test has been developed for the White Gloving gene.

W - White Locus (epistatic)

Genotype

Description

Phenotype

W/W

Homozygous - White masking other colour genes

Solid white

W/w

Heterozygous - White - carrying non white and masking other colour genes

Solid white

w/w

Homozygous - Non white, other colour genes not masked

No effect - no white

S - White Spotting (Piebald) Locus

Genotype

Description

Phenotype

S/S

Homozygous - White spotted

Piebald: medium to high levels of white spotting e.g. Van pattern or solid white

S/s

Heterozygous - White spotted carrying non-spotting

Piebald: low to medium levels of white spotting

s/s

Homozygous - Non White Piebald-spotting.

Non-spotted: no white spotting

G - Birman-specific White Gloving Locus (confirmed)

Genotype

Description

Phenotype

N/N

Homozygous - Dominant - no gloving

No white gloving.

N/G

Heterozygous - non-gloved carrying white gloving

No white gloving.

G/G

Homozygous - white gloved

White gloves.

Sb - White Mittening Locus (posited)

Genotype

Description

Phenotype

Sb/Sb

Homozygous - Incompete dominance - white mitted

White mitts with variable expression.

Sb/sb

Heterozygous - White mitted carrying non-mitted

White mitts with variable expression.

sb/sb

Homozygous - Non mitted

No white mitts.

Spy - York Chocolate White Patterning Locus (posited)

Genotype

Description

Phenotype

Spy/Spy

Homozygous - Consistent white pattern

Consistent York Chocolate white pattern

Spy/spy

Heterozygous - Consistent white pattern carrying non-white-patterned

Consistent York Chocolate white pattern

spy/spy

Homozygous - Non-white-patterned

No white pattern

 

 

TABBY AND TABBY MODIFIERS

The agouti gene (A/a) determines whether the background colour is agouti or solid i.e. whether the tabby genes present are expressed or not. It codes for agouti signalling protein (ASIP). The dominant, wild-type A causes the agouti shift phenomenon which causes hairs to be black pigmented at the tips and orange pigmented at the roots, allowing any underlying tabby pattern to be revealed. The recessive non-agouti (or hypermelanism) allele, prevents this shift in the pigmentation pathway and hides the tabby pattern (apart from ghost striping). The sex-linked O (orange) gene is epistatic (dominant) over non-agouti, hence red cats still have tabby markings (particularly visible in tortie cats where solid black patches and red-tabby are interspersed).

The secondary tabby locus is also called patterned/unpatterned tabby and determines whether an underlying blotched or striped pattern is manifested or not (in essence, it givesor denies permission for the tabby pattern to be expressed). The primary tabby locus determines the tabby type - classic or mackerel. The spotted pattern modifier changes these two patterns into spotted tabbies.

There are other hypothetical modifier genes affecting the overall pattern: Chaos (intermixes dark and light areas, disrupting the normal striped pattern), Confusion (adjacent hairs have different numbers and widths of colour bands) , Unconfused (adjacent hairs have consistent numbers and widths of colour bands), Erase (erases residual markings on limbs), and Roan (intermixes solid white hairs with coloured hairs). Tabby cats with both a colour inhibitor (silver/golden) gene and the Wide Band gene will appear as shaded or tipped cats while those lacking Wide Band will be silver/golden tabbies.

An unidentified "grizzled" gene in Chausie cats, that may be related to agouti gene, produces silver-tipped black fur and appears to have been inherited from the breed's wild Jungle Cat ancestors in which this trait is found.

A - Agouti Locus

Genotype

Description

Phenotype

A/A

Homozygous - Agouti

Banding present on the hair shaft, tabby

A/a

Heterozygous - Agouti - carrying non-agouti

Banding present on the hair shaft, tabby

a/a

Homozygous - Non-Agouti

No banding of the hair shaft, solid

Ta - Secondary (Ticked) Tabby Locus
(U - Unpatterned Tabby Locus - alternate symbol)

Genotype

Description

Phenotype

Ta/Ta

Homozygous - Unpatterned tabby

Ticked (Abyssinian-type) tabby, no pattern (some residual barring on lags, tail and face)

Ta/ta

Heterozygous - Agouti - carrying non-agouti

Ticked (Abyssinian-type) tabby, no pattern (some residual barring on lags, tail and face)

ta/ta

Homozygous - Non-Agouti

No effect. Mackerel or Classic tabby depending on which Primary Tabby gene is present and whether the cat is agouti or non-agouti.

 

Mackerel and Classic tabbies are modified by the ticked tabby allele and the spotted tabby allele. They must have non ticked (a/a) and non-spotted (sp/sp) alleles both present for the Mackerel or Classic tabby pattern to show up.

Spotted Tabby is a dominant modifier of both Mackerel and Classic Tabby, but is hypostatic to Ticked Tabby (is masked by epistatic ticked tabby gene). It modifies both tabby patterns into spotted patterns.

Mc - Primary Tabby Locus

Genotype

Description

Phenotype

Mc/Mc

Homozygous - Mackerel Tabby

Mackerel (Tiger) Tabby

Mc/mc

Heterozygous- Mackerel - carrying Classic Tabby

Mackerel (Tiger) Tabby

mc/mc

Homozygous - Classic Tabby

Classic (Blotched) Tabby

Sp - Spotted Tabby Locus

Genotype

Description

Phenotype

Sp/Sp

Homozygous - Spotted Tabby

Spotted Tabby

Sp/sp

Heterozygous - Spotted Tabby - carrying non spotted

Spotted Tabby

sp/sp

Homozygous - Non Spotted Tabby

No effect

Breeder observations and analysis of pedigrees have resulted in several posited tabby modifiers. The Tabby Pattern Size modifier modifies the Classic Tabby Pattern by creating pale areas within the blotched markings and may be the same as the hypothetical Chaos modifier.

The Tabby Pattern Spot Modifier converts the 2 basic tabby patterns into spotted patterns. Spotted mackerel tabby will have smaller, more numerous, more vertically aligned spots while spotted classic tabby will have larger spots with less evident vertical alignment.

Th - Tabby Pattern Size Modifier Locus (posited)

Genotype

Description

Phenotype

Thl/Thl

Homozygous - unmodified classic tabby pattern

Classic Tabby

Thl/ths

Heterozygous - classic Tabby carrying Sokoke pattern

Classic Tabby

Ths/ths

Homozygous - small pattern classic tabby

Sokoke-pattern classic tabby with pale areas within the dark markings.

Pm - Tabby Pattern Spot Modifier Locus (posited)

Genotype

Description

Phenotype

Pmf/Pmf

Homozygous - modified tabby pattern

Spotted tabby (large spots when interacting with classic tabby, small spots when interacting with mackerel tabby)

Pmf/pmu

Heterozygous - modified tabby carrying unmodified tabby

Spotted tabby (large spots when interacting with classic tabby, small spots when interacting with mackerel tabby)

Pmu/pmu

Homozygous - unmodified tabby pattern

Classic tabby or mackerel tabby, non-spotted

There is no symbol for the Bengal Marble effect (and its "marbled" and "clouded" analogues in other spotted hybrids). It appears recessive to the spotted/rosetted pattern in the same way that classic (blotched) tabby is recessive to mackerel tabby. Marble may be the classic tabby gene modified by wild-type genes. To indicate the mode of inheritance I've simplified spotted/rosetted as being the dominant "effect" with marble being the recessive "effect" (note I am not calling them genes as I suspect they involve interactions of domestic tabby with wild spotting genes). "Bg" is not an official gene symbol.

Bg - Bengal Spotted/Rosette/Marble Pattern

Genotype

Description

Phenotype

Bg/Bg

Homozygous - Spotted/Rosetted

Spotted/Rosetted

Bg/bg

Heterozygous - Spotted/Rosetted - carrying Marble (Cloud)

Spotted/Rosetted

bg/bg

Homozygous - Marble (Cloud) Pattern

Marble (Cloud)

CHARCOAL (AGOUTI VARIANT)

The following information is courtesy Joshua Dabbs who is investigating charcoal Bengals with Terra Sinclair.

"Charcoal" is found in Bengals, especially in the early generations, and has also occurred in Savannahs due to Bengal outcrosses in breed development. Charcoal Bengals are "Aa" at the agouti locus. Charcoal is due to a variant in the agouti gene ("charcoal agouti" or APb variant) inherited from the Asian Leopard Cat reacting with the domestic cat non-agouti gene (a). Non-agouti genes develop independently in different species and though the visual effect is similar, the gene mutations are different. In hybrids, they interact to produce novel effects. The genotype APba results in an intermediate form between agouti and non-agouti. The intermediate form causes an increase in black pigmentation unevenly distributed throughout the coat. The distribution of pigmentation varies between cat, and often causes coloration and features to become more exaggerated to where they take on an entirely new appearance. The domestic cat version of the Agouti (A) gene is termed AFc in the table below.

Charcoal is now seen many generations down the line. Joshua Dabbs and Terra Sinclair investigated a number of pedigrees that supported that theory on inheritance of charcoal. These include a Bengal melanistic carrier that when paired with an F-Generation Bengal (F1 to F4 = 1 to 4 generations removed from a wild parent) produced charcoal colored brown spotted offspring. Early on in the breed history, charcoals were not properly identified as they they did not always pass their colouration to the next generation. They were misidentified as minks, smokes (from silver smoke Egyptian Mau outcrosses) or unrufoused browns. A high degree of rufism was sought in the original Bengals and the seemingly unrufoused browns were undesirable. A greater interest in the unrufoused Bengals (e.g. in silvers and melanistics (smokes)) has increased interest in, and acceptance of, the charcoal series.

A - Agouti Locus

Genotype

Description

Phenotype

APb/APb

Homozygous - Agouti (ALC gene)

Normal contrast Bengal pattern

AFc/APb

Heterozygous - Domestic gene agouti and ALC agouti

Normal contrast Bengal pattern

AFc/AFc

Homozygous - Agouti (Domestic gene)

Normal contrast Bengal pattern

APb/a

Heterozygous - Charcoal - carrying non-agouti

Charcoal Bengal pattern

a/a

Homozygous - Non-Agouti

No banding of the hair shaft, "melanistic" Bengal

Charcoal Bengals vary in appearance though there are identifying factors known as "Zorro" markings. Charcoals have pure white or off-white goggles around the eyes while smokes have ghost tabby markings. Accompanying the white goggles there is usually a dark "charcoal mask" from the forehead, down the nose-bridge and often underneath the eyes and extending into the mascara-lines; the mask resembles an upside-down "Y". Charcoals also have an unbroken "cape" or "sheet" down their backs (broad back-stripe), in some cats this extends into the patterns closest to the spine-line while others have a narrower "modified" cape running down the back. Charcoal Bengals, including the browns, tend to have silver glitter, rather than either gold glitter (on normal tawny colours) or crystal glitter (on the snows and silvers).

Charcoal Brown is the most common charcoal colour; some have a uniform charcoal colour, while others have lighter background on their sides and darker background towards the top and tail. Charcoal Browns may be born looking silver due to black markings on a light greyish, background. Others ("black charcoals") are born so dark they may appear melanistic, but the background lightens as the kittens grow. Charcoal silver, when paired with a regular silver Bengal, results in higher contrast in the kittens. Charcoal silvers may be born very dark, resembling a silver smoke except for the white facial markings, becoming black-on-silver as they grow; the darker ground colour also masks the appearance of tarnishing. Colourpoint variants show darker pigmentation in their pattern or the pointing (e.g. in lynx point) is more prominent due to the higher level of pigmentation. Charcoal Snows have a greater contrast with darker markings than regular snows. Charcoal Marbles have tended to carry a sheet of colour rather than having distinct marble patterning.

Charcoal Savannahs have white or off-white goggles around the eyes and a distinctive dark nose. Rather than a pronounced mask or cape (as in bengals), there appear to be dense tabby markings between the ears. The background colour is grey rather than golden/tawny. The colour seems to trace back to the Kirembo line and has turned up in the USA and UK.

 

COLOUR EXTENSION: NORWEGIAN FOREST CAT "AMBER", "GOLDEN" SIBERIAN, BURMESE "RUSSET", BENGAL "SORREL" & "RUFOUSING"

The Extension gene (symbol E) or red factor controls the production of red and black pigment. The dominant allele E produces black pigment in the coat while the recessive allele e produces red pigment. The name comes from the effect of black or brown pigment not being extended throughout the whole coat, but being restricted to the skin of the extremities and to the eyes (for example in bay horses). Amber is due to a recessive mutation in the MC1R gene.

In Norwegian Forest Cats, this brightens black areas of the coat, modifying Black and Blue to Amber and Light Amber respectively. It has not yet been found in combination with other genes recessive to black. So far, it has only been observed in Norwegian Forest Cats where cinnamon and fawn alleles are known to be absent and in Bengals where it is believed to cause rufousing. It has also been called "fox". It may be present in other breeds, but its similarity to fawn and cinnamon means it may not have been identified as the Extension Gene (also known as Black Modifier or Agouti Modifier) in those breeds. The extension locus (the melanocortin receptor) or its ligands (molecules that bind to that receptor), control melanocyte stimulating hormone and agouti signaling protein.

Similar to amber is russet, which turned up in a line of seal (brown) European-style Burmese in New Zealand in 2007. It has subsequently occurred found in the related Mandalay (similar to the Asian in Europe) and appears to be a mutation of the extension gene. The first known russet was a pure-bred Burmese called “Molly” in 2007. There is now an experimental programme in NZ to breed Russet Burmese and to investigate dilute russet, russet tabby and solid russet (as opposed to the Burmese sepia form of russet).

The first russet kitten “Molly” was born an "odd-coloured lilac (lavender)" which gradually lightened as she grew, progressing through lilac-caramel and chocolate ticked tabby and then dramatically changing to red. Chocolate ticked tabby and red were both impossible from her pedigree, and in any case, reds are not born as chocolate tabbies! Several more unusually coloured kittens were born in different litters and all went through the same colour/pattern changes. The ancestors of these kittens were seal Burmese and had no silver, tabby or Mandalay (Asian) blood. The pedigree had both dilute and chocolate, there were no reds, creams or torties until 4 generations back. DNA testing showed some kittens to be genetically seal and other genetically chocolate. Hence the new colour is due to a different mutation currently known as russet. Russet appears to be due to a recessive mutation that causes black pigment (eumelanin) to gradually fade to a minimal amount while leaving red pigment (phaeomelanin)unaffected.

Russet kittens resemble tabbies at birth, but have pink noses and paw-pads, pale fur around the pads and genitalia and a pale tail-tip - all of which would be dark in tabbies. The muzzle and fur around the eye is ivory. The back is solidly dark rather than ticked, becoming pale ivory halfway down the flanks. The back becomes more ticked appearance, almost a saddle, as kittens undergo the colour change and the face becomes reddish. By age two, they may resemble a red Burmese. It differs from amber as ambers have dark noses and paw-pads. Non-agouti (solid) amber kittens are very dark with a dark face that is last to go red while russet kittens have off-white faces (possible due to Burmese sepia gene in the mix), which are the first part to go red (rather than the last as in ambers), and pale undersides. The russet colour change appears to be slower than the amber colour change. Russet kittens to date have been larger at birth than their siblings and somewhat on the large side as adults.

"Golden" or "golden tabby" Siberians may also have the recessive (non-extension) allele. The name "zoloty" (Russian for golden) has been suggested for this mutation because the term "golden" is already used for non-silver tipped, shaded and smoke cats.

A high rufous Bengal (and Toyger) has a very reddish background, while a "Sorrel" Bengal is one where the pattern colour has faded from black to reddish brown. The term "sorrel" is an informal name for the mutation. The background colour of early Bengals has more highly rufoused than the golden colour preferred today.

E - Extension Locus

Genotype

Description

Phenotype

E/E

Homozygous - full-extension

Allow all other colors genes to show true.

E/e

Heterozygous - full-extension - carrying non-extension

Allow all other colors genes to show true.

e/e

Homozygous - Non-extension

Restrict expression of eumelanin colours, convert eumelanin to phaeomelanin (primarily on torso). Black becomes Amber; Blue becomes Light Amber

Bengal rufousing (production of red pigment in place of black/brown) is distinct from tarnishing (where red pigment is not fully suppressed by the inhibitor (silver) gene). In Bengals, excepting silvers and melanistics, a high degree of rufousing is desirable.

 

GLITTER, SATIN, GRIZZLE, TWEED AND MERLE

The Bengal Glitter Gene causes the golden glittered effect on Bengal cats and is inherited either from the wild ancestors (both Asian Leopard Cats and the Margay have been used in foundation cats) or from a domestic cat used in the foundation stock. Initially there was thought to be a single recessive glitter gene termed "gl".

gl - Bengal Glitter Locus (posited)

Genotype

Description

Phenotype

Gl/Gl

Homozygous - unglittered

Normal coat.

Gl/gl

Heterozygous - unglittered carrying glitter

Normal coat.

gl/gl

Homozygous - glittered

Coat has sparkling glitter effect.

Further study of hair types suggest there are 2 different types of glitter which are currently termed "Mica" and "Satin".

Mica glitter affects the tips of hairs. Homozygous recessive mi results in reflective hair-tips with what appear to be small flecks of mica (a highly reflective silicate crystal) embedded in the tip and visible under a microscope. Unlike the satin mutation, mica only affects the hair-tip. It was present in a domestic cat used in Jean Mill's original hybrids between Asian Leopard Cats and domestics. Glitter type is related to colour: charcoal Bengals have silver glitter; "normal" tawny Bengals have gold glitter and snow/silver series bengals have crystal glitter.

Mi - Mica Glitter Locus (posited)

Genotype

Description

Phenotype

Mi/Mi

Homozygous - non-satin

Normal coat.

Mi/mi

Heterozygous - non-satin carrying satin

Normal coat.

mi/mi

Homozygous - mica glittered

Coat has sparkling glitter effect.

Satin (or satin glitter) affects the whole of the hair shaft and is found in many rodents (in some species, homozygous satin results in balding). The hair shaft is coated along its length with reflective amterial. This refracts light and give the coat a pearlised effect also termed "oyster". The hair is also soft, smooth and silky. This gene is found only in Tennesse Rexes where it appears linked to the curled hair causing the "radical satin" effect. Straight haired variants have a less pronounced pearly appearance and appear to have some air pockets in the hairs.

Sa - Satin Locus (posited)

Genotype

Description

Phenotype

Sa/Sa

Homozygous - unglittered

Normal coat.

Sa/sa

Heterozygous - unglittered carrying satin

Normal coat.

sa/sa

Homozygous - mica glittered

Coat has satin/pearlised sheen.

The Grizzle gene has been mainly seen in silver-tipped black Chausie has not been fully investigated. It appears to have been introduced from melanistic Jungle Cats (F chaus) in the same way that Glitter was introduced into the Bengal for its wild parents. Each grizzled hair has a black base with 5 bands of color ending in a black tip. Grizzle/silver tipped black is also seen in Jungle Cats and is a dominant gene and probably a mutation of either the agouti or extension gene. Although most noticeable on a black background, grizzle can occur with all the Chausie colourations.

Tweed is a recently noted colour mutation similar to roan in horses. White hairs are evenly intermixed with the solid base colour, such as black, to give a salt and pepper effect. Since all cats noted with this mutation were neutered rescue cats, it has not yet been investigated.

Merle occurs in red, cream and apricot silvers and results from uneven tipping. Visually it is similar to merle in dogs and mice and gives a solid base color with lighter patches resulting in a mottled or uneven speckled effect. Merle is better known in dogs where it also modifies the colour of the eyes, nose and paw pads. In cats it does not appear to be a merle mutation - solid/self reds have a residual tabby pattern because the non-agouti gene does not affect red pigment in the same way it affects black pigment. This can result in uneven tipping on cats with the silver inhibitor gene. Where the patches are large and irregular it is termed merle. Smaller more regular darker patches are also known as dapple.

COLOUR INHIBITOR GENES

The main colour inhibitor gene gives the cat a silver or golden undercoat. The degree of colour inhibition creating the differences between shaded and tipped silvers/goldens are believed due to the presence or absence of the Wide Band gene that determines the width of silver/gold undercoat band caused by inhibitor gene. Cats with both the Inhibitor gene and the Wide band gene appear as silver/golden shaded or tipped cats while those without it are silver/golden tabbies.

Dominant allele (I) produces that are fully colored only at the tip and have a white base. other genes influence the degree of tipping (the proprotion of each hair that is pigmented). Recessive allele (ii), combines with the agouti gene, to produce a golden undercoat. Poor (incomplete) expression of these or conflict with other genes results in tarnishing or excessively grey undercoat. Poor expression of non-agouti or over-expression of melanin inhibitor causes "smoke" cats to be excessively pale.

Another colour inhibitor that mimics silver has also been noted.

Dominant inhibitor + non-agouti = smoke series.
Dominant inhibitor + agouti = silver tabby/shaded silver/tipped silver series (variable expression).
Recessive inhibitor + non-agouti = golden smoke series.
Recessive inhibitor + agouti = golden tabby/shaded golden/tipped golden series (variable expression). Note: wide-band on its own may cause this, rather than recessive inhibitor.

Dominant Golden is a "late colour change" gene and mode of inheritance not confirmed. Kittens born as silvers may turn golden at 2-3 years old. Additionally, golden-from-birth cats may produce silver kittens (considered impossible as golden is recessive to silver and should breed true) . Seen in some Persian lines.

I - Colour Inhibitor Locus

Genotype

Description

Phenotype

I/I

Homozygous - Inhibitor - Silver

Silver smoke/silver tabby/tipped (chinchilla)/shaded silver

I/i

Heterozygous - Inhibitor - carrier of non-inhibitor

Silver smoke/silver tabby/tipped (chinchilla)/shaded silver

i/i

Homozygous - Recessive inhibitor (non-silver, possibly golden)

Non-silver (possibly Golden smoke/golden tabby/golden tipped/shaded golden)

  

Dg - Dominant Golden Locus (no official gene symbol assigned)

Genotype

Description

Phenotype

Dg/Dg

Homozygous

Not yet known if late colour change cats have the dominant or recessive form of the gene.

Dg/dg

Heterozygous

 

dg/dg

Homozygous

 

Wb - Wide Band Locus

Genotype

Description

Phenotype

Wb/Wb

Homozygous - Wide Band

Tipped

Wb/wb

Heterozygous - Wide Band carrying non-Wide Band

Shaded

wb/wb

Homozygous - Non-Wide-Band

Tabby

 

 

HAIR LENGTH AND TYPE

In general, shorthair is dominant to longhair. Shorthaired cats sometimes produce longhairs due to a hidden recessive gene. Such carriers, and their offspring, are often removed from the breeding programme to eliminate undesirable recessives. Longhaired cats have 2 recessive genes for the longhaired trait and should always breed true for longhair. However, a rare autosomal shorthair gene that is recessive to longhair has been observed in some Persians lines where longhaired cats produced shorthaired kittens.

There appears to be a dominant gene in the York Chocolate breed determining absence or presence of undercoat. This gene may be present in other sleek-coated breeds (absence of undercoat would be an advantage in a hot climate).

The variability in longhairs is noted in the following:

  • Kehler, J. S., V. A. David, A. A. Scha¨ffer, E. Eizirik, D. K. Ryugo et al., 2007 Four separate mutations in the feline Fibroblast Growth Factor 5 gene determine the long-cats. J. Hered. 98: 555–566.
A further 2 longhair mutations have been identified at UC Davis, making a total of six separate mutations.

L - Hair Length Locus

Genotype

Description

Phenotype

L/L

Homozygous - Shorthair

Shorthair (variable expression from Oriental type to Exotic shorthair type)

L/l

Heterozygous - Shorthair - carrying long hair

Shorthair (variable expression from Oriental type to Exotic shorthair type)

l/l

Homozygous - longhair

Longhair (variable expression from semi-long to Persian type)

ls - Recessive Shorthair Locus (provisional gene symbol)

Genotype

Description

Phenotype

Ls/Ls

Homozygous - Longhair

Longhair

Ls/ls

Heterozygous - Longhair - carrying short hair

Longhair

ls/ls

Homozygous - Shorthair

Shorthair

Yuc - York Chocolate Undercoat Locus (posited)

Genotype

Description

Phenotype

Yuc/Yuc

Homozygous - lacks undercoat

Sleek fur, no undercoat

Yuc/yuc

Heterozygous - lacks undercoat

Sleek fur, no undercoat

yuc/yuc

Homozygous - full undercoat

Undercoat present

 

HAIRLESS AND REX MUTATIONS

In addition to the genes listed here, there are a number of hairless mutations and rex mutations, both extinct and extant, whose mode of inheritance is not known. Many of these unknown genes may be identical to currently bred mutations, while others will be novel mutations. The effect of rex and wirehair genes also depends on the coat length and probably on polygenes. Where two rex genes on different loci are present, these may interact to produce a coat type different to either parent.

The Canadian hairless gene is recessive to normal hair, but is dominant to Devon Rex (in 2010 DNA analysis found that Devon Rex Sphynx genes are alleles of the same gene, previously they were beleived to be different loci with Sphynx being epistatic to Devon Rex). Two other extinct recessive hairless genes have been noted, but the locus not identified: French Hairless (h) and Redcar (UK) Hairless (hd). The Russian Hairless gene is a dominant hairless trait found in the Peterbald and Don Sphynx where an initial rex coat may be present and hairlessness develops progressively during the first 24 months.

The extremely rare Kohana Cat (Hawaiian hairless) was believed to be due to the presence and interaction of both the dominant Russian Hairless allele and the recessive Canadian Sphynx allele or alternatively to a new dominant gene mutation. DNA analysis in 2010 found that the Hawaiian hairless was the same mutation as Canadian Sphynx. The analysis also found that Sphynx and Devon Rex are different mutations of the same gene. The relationship between these mutations from most dominant to most recessive is: Normal Hair >> Sphynx >> Devon Rex

Wirehair is a dominant allele with incomplete penetrance i.e. cats with the dominant wirehair allele (genetically wirehair cats) may have a normal coat, but produce wirehaired offspring.

r - Cornish/German Rex Locus

Genotype

Description

Phenotype

R/R

Homozygous - Straight haired cat

Standard coat - no effect

R/r

Heterozygous - Straight haired cat carrying - C rexing

Standard coat - no effect

r/r

Homozygous - C rexed cat

Rexed - wavy fur

re - Devon Rex Locus

Genotype

Description

Phenotype

Re/Re

Homozygous - Straight haired cat

Standard coat - no effect

Re/re

Heterozygous - Straight haired cat carrying - D rexing

Standard coat - no effect

re/re

Homozygous - D rexed cat

Rexed - wavy fur

ro - Oregon Rex Locus

Genotype

Description

Phenotype

Ro/Ro

Homozygous - Straight haired cat

Standard coat - no effect

Ro/ro

Heterozygous - Straight haired cat carrying - O rexing

Standard coat - no effect

ro/ro

Homozygous - O rexed cat

Rexed - wavy fur

Se - Selkirk Rex Locus

Genotype

Description

Phenotype

Se/Se

Homozygous - S Rex cat

Rexed - wavy fur, finer, curlier and sparser than heterozygote

Se/se

Heterozygous - S Rexed cat - carrying normal coat

Rexed - wavy fur, preferred coat type

se/se

Homozygous - Straight haired cat

Standard coat - no effect

Lp - Laperm Locus

Genotype

Description

Phenotype

LP/LP

Homozygous - LP Rex cat

Rexed - wavy or ringletted fur

LP/lp

Heterozygous - LP Rexed cat - carrying normal coat

Rexed - wavy or ringletted fur

lp/lp

Homozygous - Straight haired cat

Standard coat - no effect

Wh - Wirehair Locus

Genotype

Description

Phenotype

Wh/Wh

Homozygous - Wirehair

Bristly, wiry fur

Wh/wh

Heterozygous - Wirehair carrying - staight hair

Bristly, wiry fur

wh/wh

Homozygous - Straight hair

Standard coat - no effect

hr - Canadian Hairless (Sphynx) Locus

Genotype

Description

Phenotype

Hr/Hr

Homozygous - Coated cat

Standard coat

Hr/hr

Heterozygous - Coated cat - carrying Sphynx hairless allele

Standard coat

hr/hr

Homozygous - Sphynx Hairless cat

hairless cat

Hp- Russian Hairless Locus

Genotype

Description

Phenotype

Hp/Hp

Homozygous - Hairless

Hairless cat

Hp/hp

Heterozygous - Hairless -carrying normal coat

Hairless cat

hp/hp

Homozygous - Normal Coated cat

Standard coat - no effect

 

EARS

The curled ear trait in American Curls and derivative breeds is a dominant trait with variable expression. A curled ear mutation was observed in a female stray Australian cat. She did not pass this on to her offspring. Back-crossing to identify a possible recessive curled-ear trait was impossible as the mother became ill and had to be spayed.

Forward folded ears is a dominant trait with incomplete penetrance and linked to disabling skeletal problems, especially in homozygotes. Incomplete penetrance means a prick-eared cat may genetically be a fold-eared cat.

Cu - Curled Ears Locus

Genotype

Description

Phenotype

Cu/Cu

Homozygous - Curled ears

Ears Curl backwards (variable expression)

Cu/cu

Heterozygous - Curled Ears - carrying normal ears

Ears Curl backwards (variable expression)

cu/cu

Homozygous - Normal ears

Standard ears - no effect

Cua - Australian Curl Ears Locus (posited)

Genotype

Description

Phenotype

Cua/Cua

Homozygous - Prick ears

Normal upright ears

Cua/cua

Heterozygous - Prick Ears - carrying curled ears

Normal upright ears

cua/cua

Homozygous - Curled ears

Ears Curl backwards

Fd - Folded Ears Locus

Genotype

Description

Phenotype

Fd/Fd

Homozygous - Folded Ears

Ears Folded Forwards

Fd/fd

Heterozygous - Folded Ears - carrying non-folded ears or standard ears (rare)

Ears Folded Forwards

fd/fd

Homozygous - Prick-ears

Prick-ears

 

EYES

Many genes govern eye colour, creating shades ranging from blue to green to yellow to orange and many shades inbetween. The epistatic white gene can cause blue eyes as can the white spotting gene where there is high grade white spotting. The Siamese colourpoint allele produces blue eyes while the Burmese Sepia allele has orange eyes; cat with one of each (Tonkinese) having aqua eyes. Blue-eyed and pink-eyed albinos also occur and are part of the colourpoint series of alleles.

A notable gene affecting eye colour is that in the Ojos Azules. This is a dominant mutation giving blue eyes, regardless of the coat colour, and white splashed extremities. Other blue-eyed mutations have been observed, but not selectively bred.

Oj - Ojos Azules Locus (no official gene symbol assigned?)

Genotype

Description

Phenotype

Oj/Oj

Homozygous - Ojos Azules eye colour

Blue eyes, white splashed extremities.

Oj/oj

Heterozygous - Ojos Azules carrying other eye colour

Blue eyes, white splashed extremities.

oj/oj

Homozygous - non Ojos Azules eye colour

Any other eye colour, any markings on extremities are due to other White Spotting genes

 

TAILS

The normal tail is full-tailed. There are 2 identified tail mutations. Japanese Bobtail, found throughout Asia is a recessive. The Kurilian’s bobbed tail is due to a dominant gene with incomplete penetrance, while the similarly named Karelian’s bobbed tail is a recessive gene. These are not associated with any skeletal abnormalities. Manx taillessness is a dominant trait with variable expression ranging from from tailless (Rumpy) through rumpy riser, stumpy and longy. It is a classic lethal gene and is associated with skeletal and spinal problems (these may be due to "linked genes" as breeders have reduced the incidence of Manx syndrome).

Jb - Japanese Bobtail Locus
(also Karelian Bobtail)

Genotype

Description

Phenotype

Jb/Jb

Homozygous - Normal tail

Normal tail

Jb/jb

Heterozygous - Normal tail carrying bobtail

Normal tail

jb/jb

Homozygous- Japanese Bobtail

Short curled bobtail

Kur - Kurilian Bobtail Locus
No official gene symbol assigned yet

Genotype

Description

Phenotype

Kur/Kur

Homozygous - Bobtail

Short curled bobtail

Kur/kur

Heterozygous - Bobtail tail carrying normal tail

Short tail, may or may not be curled

kur/kur

Homozygous- Non Kurilian Bobtail

Normal tail

M - Manx taillessness Locus

Genotype

Description

Phenotype

M/M

Homozygous - Tailless, die in utero

Die in utero, gross neural tube defects.

M/m

Heterozygous - Tailless - carrying normal tail

Ranges from no tail (rumpy) to short tail

m/m

Homozygous - Normal tail

Full-length tail

 

LIMBS AND PAWS

The Munchkin mutation affects limb length only. It is not achondroplastic dwarfism as the cranium is unaffected. It is probably hypochondroplasia or pseudochondroplasia. Munchkin is an autosomal dominant, possibly lethal in homozygous state as breeders have reported litters smaller than average.

Classic (mitten-foot/thumb-cat) polydactyly is dominant in action with variable expression and incomplete penetrance. This gene has only cosmetic effect ranging from one or more extra toes, usually in mitten-foot conformation. Due to incomplete dominance, some normal footed cats are genetically polydactyl. Other polydactyl genes with other modes of inheritance are probable; so far the Radial Hypoplasia gene has been identified as one cause of patty-foot polydactyly. Radial hypoplasia ranges from cosmetic (polydactyly) to debilitating (absent radius) and patty-foot cats are not selectively bred. Other polydactyl mutations, both dominant and recessive, are likely.

The identified form of Syndactyly (split foot) in cats is a dominant gene resulting in a two-digit paw that resembles a lobster-claw. It is considered debilitating and is not selectively bred. There are probably phenotypically similar conditions, due to other mutations, which have not been investigated.

Mk - Munchkin

Genotype

Description

Phenotype

Mk/Mk

Homozygous - Short legs

Munchkin

Mk/mk

Heterozygous - Short legs

Munchkin

Mk/mk

Homozygous - Normal legs

Normal length legs

Pd - Polydactyl Locus

Genotype

Description

Phenotype

Pd/Pd

Homozygous - Polydactyl

Extra toes

Pd/pd

Heterozygous - Polydactyl - carrying normal number of toes

Extra toes

Pd/pd

Homozygous - Normal number of toes

Standard number of toes - no effect

Sh - Split Foot Locus

Genotype

Description

Phenotype

Sh/Sh

Homozygous - Syndactyl

Split foot (lobster claw syndrome)

Sh/sh

Heterozygous - Syndactyl carrying normal number of toes

Split foot (lobster claw syndrome)

sh/sh

Homozygous - Normal number of toes

Standard number of toes - no effect

MESSYBEAST : BASIC GENETICS FOR BREEDERS & CAT LOVERS