Mutations within the FGF5 gene are associated with hair length in cats

Hereditary hair length variability in mice and dogs is caused by mutations within the fibroblast growth factor 5 (FGF5) gene. The aim of this study was to evaluate the feline FGF5 orthologue as a functional candidate gene for the long hair phenotype in cats, which is recessive to short hair. We amplified the feline FGF5 cDNA and characterised two alternatively spliced transcripts by RT-PCR. Comparative cDNA and genomic DNA sequencing of long- and short-haired cats revealed four non-synonymous polymorphisms in the FGF5 coding sequence. A missense mutation (AM412646: c. 194C > A) was found in the homozygous state in 25 long-haired Somali, Persian, Maine Coon, Ragdoll and crossbred cats. Fifty-five short-haired cats had zero or one copy of this allele. Additionally, we found perfect co-segregation of the c. 194C > A mutation within two independent pedigrees segregating for hair length. A second FGF5 exon 1 missense mutation ( AM412646: c. 182T > A) was found exclusively in long-haired Norwegian Forest cats. The c. 182T > A mutation probably represents a second FGF5 mutation responsible for long hair in cats. In addition to the c. 194C > A mutation, a frameshift mutation ( AM412646: c. 474delT) was found with a high frequency in the long- haired Maine Coon breed. Finally, a missense mutation ( AM412646: c. 475A > C) was also associated with the long-haired phenotype in some breeds. However, as one short-haired cat was homozygous for this polymorphism, it is unlikely that it has a functional role in the determination of hair length.