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Гены окрасов кошек

TABBY AND TABBY MODIFIERS

 

The agouti gene determines whether the background colour is agouti or solid i.e. whether the tabby genes present are expressed or not. 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


GLITTER AND GRIZZLE

The Bengal Glitter Gene causes the golden glittered effect on Bengal cats and is presumably inherited from the wild ancestors (both Asian Leopard Cats and the Margay have been used in foundation cats).

The Grizzle gene 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. Silver tipped black is seen in Jungle Cats.


gl - Bengal Glitter Locus

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.


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.

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).

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 (golden)
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