Also referred to as blue or Maltese, grey is a common coat colour in both purebred and domestic cats. Grey is the dilute form of black, caused by the aptly named dilution gene which is caused by a single base deletion 1 bp in the melanophilin (MLPH) gene. This gene provides instructions for making melanophilin, a carrier protein that is found in pigment-producing melanocytes. Melanophilin is essential for the even distribution, transport, and translocation of melanin (pigment granules). Menalocytes are specialised cells that contain organelles known as melanosomes. Melanosomes synthesise, store and transport melanin out of the cell via the dendrites to neighbouring keratinocytes (keratin producing cells).
The synthesis of melanin is normal in the grey cat, however, pigment granules are enlarged and instead of having an even distribution along the hair shaft, they form clumps. The result is some areas with no pigment which causes the characteristic grey colour.
The dilute gene is recessive, which means the cat must inherit two copies (one from each parent) for the gene to be expressed. In addition to the dilute gene, grey cats also carry two copies of the recessive non-agouti gene which masks the default tabby pattern. Instead of a pale background and darker stripes, the blue cat is one colour (known as self). It is sometimes possible to see ghost tabby markings on young kittens or on bright days.
Because dilute is recessive to dense, two dilute cats cannot produce a dense (black) cat, however, a cat with a dense coat colour can potentially produce dilute offspring if they carry a copy of the recessive gene, ie; D/d.
Possible outcomes
Genes come in two pairs, if a gene is dominant, it is symbolised with a capital letter while recessive genes are always characterised with a lowercase letter. D = dense, d = dilute
If the cat is homozygous for a trait, he or she carries two copies of the same gene (D/D or d/d), the heterozygous cat has inherited two different forms of a gene (D/d).
| Homozygous sire and homozygous dam (D/D x D/D) |  |
All offspring are homozygous dense. |
| One parent homozygous, one parent heterozygous (D/D x D/d) |
 |
All offspring are dense, some may carry the dilution gene |
| Both parents heterozygous (D/d x D/d) |  |
Some offspring are homozygous dense (D/D) and homozygous dilute (d/d), some are heterozygous (D/d) |
| Both sire and dam are homozygous dilute (d/d x d/d) |  |
All offspring are dilute (grey) |
White spotting gene
Some cats may also inherit the white spotting gene which results in patches of white, most commonly on the legs, underside and face of the cat. Grey and white cats are known as bi-colour.
What kind of cat is solid grey?
Grey occurs in random-bred and purebred cats. Some breeds of cat only occur in grey, which includes the following:
- Korat
- Nebelung
- Russian Blue
- Chartreux
The following breeds allow grey as well as a variety of other colours:
- American Shorthair
- American Wirehair
- British Longhair
- British Shorthair (grey is the most recognised colour, but all other colours and patterns are accepted)
- Burmese
- Cornish Rex
- Devon Rex
- Exotic Shorthair
- LaPerm
- Munchkin
- Oriental Longhair
- Oriental Shorthair
- Scottish Fold
- Selkirk Rex
Frequently asked questions
Are grey cats male or female?
Grey cats can be male or female.
Are grey cats rare?
Grey is less common than tabbies and other solid colours, but they are not rare. As the grey cat must inherit two copies of the dilute gene, grey is less common than black.
How much does a grey cat cost?
The cost of a grey cat varies from breed to breed. A moggy from an animal shelter will cost approximately $150 – $200. This fee will include spay or neuter, vaccinations and parasite control.
Purebred cats are more expensive and the cost can vary depending on the breed. The Russian Blue is relatively common and will cost between $1,000 to $2,000. The Korat, Chartreux and Nebelung are rare breeds and as such, will cost more. Breeds which permit blue such as British Shorthair, Burmese, Persian etc., are also widespread and can cost between $1,000 to $2,000.
How do I know if my grey cat is purebred?
While grey is a stunning coat colour that is popular in purebred cats, the majority of grey cats with no history are moggies. The only way to determine the genetic background of a grey cat whose history is not known is a DNA test from a reputable company or university.
Feature image: Seregraff/Shutterstock