Genetic determination of hair texture and length in the Devon Rex

Marie Abitbol Professor of Genetics VetAgro Sup, Veterinary Campus of Lyon :

The rex phenotype is characterised by the presence of a wavy, curly, frizzy or notched coat, more or less long and of variable densitývariable. In the Devon Rex, the responsible mutation has beeńidentified. It is a mutation in the KRT71 (keratin 71) gene, a gene that is also implicated in the nakednesś of the Sphynx (Gandolfi et al. 2010). The Devon's notched/curly coat mutation is autosomal recessive. This means that the cat, in order to have the notched coat, must carry two copies (two alleles) of the mutation. The mutation has been called "re". So a Devon rex is re/re. It is said to be homozygous for the re mutation. In the Sphynx, the nakedness mutation has been called hr. It is also autosomal recessive. Sphynx are therefore hr/hr. A DNA test exists for the re and hr mutations. It has been shown that some Sphynx can carry the Devon mutation, because of the common history of these two breeds, which were mixed at the very beginning of their existence. So there are Sphynxes, a little hairier than the standard requires, which are hr/re. It is therefore not entirely impossible that some Devons may also carry the Sphynx mutation, although this has not yet been proven. In the event that an adult Devon is observed to be permanently hairless, it is possible to have the DNA test done to rule out the presence of the Sphynx mutation. However, it should be noted that inter-individual, hormonal and seasonal variability in coat quality in Devons are common, and not related to the Sphynx mutation. The test should therefore be reserved for special cases of near-naked Devons. In other cases it is useless. Coat length is governed by a two allele gene called L (Longhair). The L allele, dominant, is responsible for a short coat while the l allele, recessive, is responsible for a long coat (called longhair for the Persian and semi-longhair for the other breeds, in France). In the following text, longhair and semi-longhair will be grouped together and called "longhair". Four mutations, present in the different cat breeds, have beeń identified for the l allele, in a gene called FGF5 (fibroblast growth factor, Kehler et al. 2007; Drögemüller et al. 2007). A shorthair cat can therefore be L/L (it is not a carrier of the longhair mutation, it will only produce shorthair kittens) or L/L (it carries the longhair mutation and mated with a longhair cat or a carrier cat it can produce longhair kittens). The longhair mutation is present in the Devon Rex. Two Devon Rex shorthair cats (breed standard) can therefore sire longhair kittens, if both breeders are L/l. A longhair Devon is recognisable by the length of its coat, especially at the tail (plume) and the appearance of the coat, which resembles that of the Selkirk rex but is less voluminous. A DNA-test is available, to find out if a Devon rex breeder is a carrier of the longhair mutation or to confirm, for example, that a kitten with a particularly long coat is homozygous l/l for the longhair mutation.

References: Drögemüller, C., Rüfenacht, S., Wichert, B., Leeb, T. 2007. Mutations within the FGF5 gene are associated with hair length in cats. Anim Genet. 38 : 218-221. Gandolfi, B., Outerbridge, C.A., Beresford, L.G., Myers, J.A., Pimentel, M., Alhaddad, H., Grahn, J.C., Grahn, R.A., Lyons, L.A. 2010. The naked truth: Sphynx and Devon Rex cat breed mutations in KRT71. Mamm Genome 21: 509-515. Kehler, J.S., David, V.A., Schäffer, A.A., Bajema, K., Eizirik, E., Ryugo, D.K., Hannah, S.S., O'Brien, S.J., Menotti-Raymond, M. 2007. Four independent mutations in the feline fibroblast growth factor 5 gene determine the long-haired phenotype in domestic cats. J Hered. 98: 555-566.

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