Maine Coons were known to often be polydactyl – having extra toes on two or all four feet. It is estimated that in the 50s and 60s, when the breed was first recognized, almost half of all MCO were polydactyl.
At WesterosCat Maine Coon we do not have polydactyl cats in breeding, but knowing a little about the background and genetics is good nevertheless.
There are various types of polydactyl paws:
- “Mitten” – extra “thumb” toes
- “Pattyfoot” – several extra toes, but no “thumb”
Polydactyly is normally a dominant trait, and can be inherited from one of the parents. In Maine Coon the most common mutation is called the “Hemingway mutation” Hw. This can be DNA-tested.
|Type||Mutation||Can be tested where||Found in breeds|
|“Mitten” Hw P forepaws||LIMBR1 c.479A>G||MyCatDNA, Genoscoper||MCO, Pixiebob|
|PP all paws||LIMBR1 c.481A>T||MyCatDNA, Genoscoper||Domestic shorthair|
|PP all paws||LIMBR1 G257C||Domestic shorthair|
Polydactyly means the presence of extra digits. Mutations in the ZRS modulator cause polydactyly in cats. Three different causative mutations have heen found from cat lines originating from different geographical locations. All of these mutations result in a mutation-typical phenotype.
The ZRS modulator is responsible for controlling the signaling molecule SHH in the developing limb buds. Mutations in this modulator cause polydactyly in cats via altered modulator function. Polydactyly in Hemingway cats is caused by a dominant mutation of the ZRS modulator (A479G). The same mutation has been found in other polydactylous cats in North America. This mutation causes polydactyly in the forelimbs. Two other dominant ZRS modulator mutations, (G257C) and CA481T), causing polydactyly have been found in British cats. These mutations cause polydactyly in all limbs. The final appearance of the cat will also depend on its genetic makeup at other loci.
The lab Antagéne in France is doing research on the genetics of polydactyl Maine Coons and it is possible to participate.
Today only some of the registries allow breeding with polydactyl Maine Coons. In FIFe breeding polydactyl cats were forbidden from 1. January 2014, a motion passed at the General Assembly in 2013.
|Registry||MCO recognized breed||poly can be registered and bred||poly can be shown|
|TICA||1979||yes||accepted in 2015|
|FIFe||1982||forbidden from 2013||never|
There are also other registries – if you have information about what rules they have I am happy to include that here, just contact me.
Messy Beast – about the genetics and background
Alterskjær Maine Coon about breeding polydactyl Maine Coon – in Norwegian