Longhair genes – langhårsgener

The natural coat for the domestic cat is shorthair. However many cat breeds have developed longhair coats.

There are 4 different types of mutations in the FGF5 gene, that give longhair cats:

Type Mutation Found in Breeds
M4 A475C All longhair and semilonghair
M3 474delT Maine Coon, Ragdoll
M2 C406T Norwegian Forest cat
M1 ins356T Ragdoll

Maine Coons are known to have two of these longhair genes in their population: M3 and M4. It is unknown if the other types also exist in Maine Coon. There is also a 5th longhair mutation in Maine Coon, still not discovered.

The Maine Coon standard (the original) says:

The fur on the front shoulders is short and should become gradually longer along the back towards the tail, ending in a shaggy, heavy coat on the “britches”. The sides of the cat’s coat should gradually get longer until the stomach is reached, where it should be long and full. A full ruff is not expected, however, there should be a slight frontal ruff beginning at the base of the ears. The fur on the tail should be long and full. Feet should be tufted. Coat should be fine, heavy, lustrous, and should fall smoothly. A slight undercoat may be carried. This is the optimum coat and will vary with climate.

As many have observed, Maine Coons have quite a bit of variation in coat length and texture.

Since a cat inherits one copy of the gene from each parent, the possible longhair combinations for MCO are:

  • M3/M3
  • M3/M4
  • M4/M4

It is uncertain how much these differences actually influence each individual cat’s coat type. We do know that within the Maine Coon breed, the variation in coat length and structure is quite large.  Actual coat types are obviously also decided by many other genes. Some also believe colours have an influence.

Laboratories that do testing of longhair types:

  • MyCatDNA/Genoscoper
  • VGL/UC Davies
  • Labogen/Laboklin


Our cats:

We do extensive DNA-testing of most of our cats, and this is what we know of their coat type. What I describe as “all-weather coat” is a bit more coarse and greasy with more protection, and also a little less silky than the softer coats – unless just bathed. Cats also typically develop more wooly coats after neutering.

Name Type EMS Description
Hieronymus M4/M4 MCO e 09 Very long coat, lots of underwool
Viggo M3/M3 MCO n 22 Medium long all-weather coat
Suki M3/M3 MCO n 09 24 Medium long extremely silky
Olenna M3/M3 MCO a 22 Medium long, soft silky plush quality, developed late
Arya M3/M4 MCO n 09 22 Still a bit short all-weather coat
Aegon M3/M4 MCO n 09 22 Medium long all-weather coat
Betzy M3/M3 MCO f 09 22 Medium long all-weather coat
Brie Mx/M3 MCO f 03 22 Medium long, very silky
Fleming M4/M4 MCO n 22 Quite long, all-weather coat
William M3/M3 MCO e 03 23 Medium long fluffy, all-weather coat
Daenerys M3/M3 MCO a 03 22 Fairly short, soft silky plush like grandmother Olenna
Drogon M3/M4 MCO n 09 24 Medium length, very silky like mother Suki

Other factors that can influence coat type: Colours and patterns. Some people say dilute, especially blue, have coats the get matted more easily, others believe to see this in silver and smoke. Traditionally brown tabbies are said to have the easiest coats to care for.

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