Introduction
The fibroblast growth factor 5 (FGF-5) gene codes for a protein and gives the necessary instructions. The FGF5 gene participates in the FGF pathway, which is an inhibitor of hair growth. (Li et al., 2022). Mutations in the FGF5 gene have been found in both humans and non-human animals, providing valuable insights into its function and how it induces or disrupts hair growth. However, while the FGF5 gene is capable of inducing the growth of thick hair in animals, in people, the mutation of the gene causes hair disorders.
The Effect of FGF5 Mutation on Humans
The impact of the FGF5 mutation on humans is unclear and variable. The most well-known biological effect of FGF5 to date is its paracrine inhibitory effect on the proliferation of cells in the external sheath of hair. Human hair follicles produce FGF5 in their higher outer root sheath cells, and FGF5 mutations cause abnormally long eyelashes (Chen et al., 2020). Nonetheless, the majority of research indicates that human FGF5 gene mutations can cause a variety of hair-related problems.
One such disorder is hypotrichosis simplex of the scalp, which is characterized by gradual scalp hair loss that begins after early childhood (Kim et al., 2020). In people with this illness, the FGF5 gene is mutated, resulting in an early stop codon, which results in a truncated protein that cannot function properly. Uncombable hair syndrome, a condition marked by dry, frizzy, and easily breakable hair, is a different condition connected to the FGF5 mutation (Kim et al., 2020). Therefore, the disorder is caused by a specific mutation in the FGF5 gene that alters the structure of the protein, leading to abnormal hair shafts and associated symptoms.
The Effect of FGF5 Mutation on Animals
As seen, a released inhibitory signal called FGF5 has the effect of preventing hair elongation. However, several animals, including cats, dogs, donkeys, goats, Syrian hamsters, and mammoths, have the long hair phenotype, which is brought on by mutations in FGF5 (Xu et al., 2020). Research has revealed that variations in the FGF5 gene can also alter an animal’s ability to develop hair.
SNP1, SNP4, and SNP5 were substantially connected with the greasy wool mass and wool thickness of SG sheep when it came to sheep wool features (Zhao et al., 2021). These findings showed that all five SNP alterations could be significant contributors to sheep’s ability to produce wool and that breed uniqueness may be the root cause of significant variability at these SNP sites between SG and SSG sheep (Zhao et al., 2021). Therefore, unlike the effect experienced by people, the opposite effect is observed in animals.
It is clear that fibroblast growth factor 5, a member of the group of fibroblast growth factors, is essential for regulating the hair development cycle while mammalian hair follicles are growing. The FGF5 gene might prevent normal hair development in mice, and a loss-of-function variation that extended the hair growth cycle resulted in aberrant hair growth (Zhao et al., 2021).
In dogs, a mutation in the FGF5 gene has been identified that is responsible for the long hair phenotype in certain breeds, such as the Afghan hound and the Komondor (Takahashi et al., 2022). In cats, the mutation was identified in breeds such as Somali, Persian, Maine Coon, and Ragdoll (Drögemüller et al., 2007). This mutation leads to decreased expression of the FGF5 protein, which in turn results in delayed hair follicle regression and prolonged hair growth. Similarly, in cats, a mutation in the FGF5 gene has been identified that is responsible for the long hair phenotype in certain breeds, such as the Persian and the Maine Coon (Takahashi et al., 2022). Consequently, the existence of gene mutation results in the creation of thick hair in animals.
How FGF5 Controls Hair Length
The way the fibroblast growth factor 5 controls hair growth is through protein. By regulating the change from anagen (the active hair growth phase) to catagen (the regression phase) in the hair cycle, the FGF5 protein plays a crucial role in the regulation of hair length. (Burg et al., 2022). During anagen, FGF5 is expressed at low levels, allowing for uninterrupted hair growth (Hébert et al., 1994). The hair follicles regress, and hair development stop as the hair follicles enter catagen, where FGF5 expression is increased (Burg et al., 2022). Alterations in hair development and other hair-related problems can result from mutations in the FGF5 gene.
Conclusion
As a result, the FGF5 gene’s mutations have shed important light on how it controls hair development in both humans and non-human animals. These mutations have been associated with a range of hair-related disorders, including hereditary hypotrichosis simplex and uncombable hair syndrome in humans and the long hair phenotype in certain dog and cat breeds. Proteins in fibroblast growth factor 5 control the growth of hair. The FGF5 protein tightly regulates the shift from anagen to catagen in the hair growth cycle, and mutations in this gene can interfere with this process, resulting in aberrant hair development. Thus, mutations in the FGF5 gene and protein can cause changes in hair growth and other issues associated with hair.
Reference List
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