Long Hair (FGF5 gene, various breeds)

The length of the hair covering the cat`s body, limbs and tail is related to a single gene called FGF5.

Definition

This trait refers to the genetic variant responsible for long hair on the body, legs and tail of cats. This variant is found in the FGF5 gene, which is involved in the regulation of hair growth in the hair follicle.

Genetic basis

The variant is recessive, therefore, long hair will be expressed in cats carrying two copies of the c.475A>C variant, also known as the M4 allele. However, cats carrying two copies of the variant are also found to have a short hair phenotype, suggesting that this mutation may not be solely responsible for hair length. Different variants have been identified in the FGF5 gene that, when combined with this variant in compound heterozygosis (one copy of each variant), could also generate a longer coat phenotype.

Other relevant information

The FGF5 gene is crucial for the regulation of the hair growth cycle. Mutations in this gene prolong the anagen phase (growth phase) of the hair cycle, resulting in longer hair. This is because FGF5 acts as a "switch" that normally stops hair growth at the end of the anagen phase. Without proper FGF5 function, hair continues to grow longer than normal.

Bibliography

Drögemüller C, Rüfenacht S, Wichert B, et al. Mutations within the FGF5 gene are associated with hair length in cats. Anim Genet. 2007