Researchers have uncovered the first gene associated with hair graying.
Published in the journal Nature Communications, the study reveals how a variant in the gene interferon regulatory factor 4 (IRF4) plays a role in the graying of human hair.
Hair graying is a process typically associated with aging. It is believed to occur when melanin - the pigment that gives hair, skin and eyes their color - is no longer produced.
For their study, co-lead author Dr. Kaustubh Adhikari, of the Department of Cell & Developmental Biology at University College London (UCL), UK, and colleagues set out to determine whether IRF4 - already known to play a role in hair, eye and skin color - is associated with hair graying.
The researchers also wanted to find out whether certain genes are responsible for the density and shape of human hair, such as whether it is straight or curly.
IRF4 gene variant correlated with hair graying in study subjects
To reach their findings, the team analyzed the DNA of 6,357 individuals - of whom 55% were female - from five Latin American countries: Brazil, Colombia, Chile, Mexico and Peru. Participants were a combination of European, Native American and African ancestry.
The researchers assessed all participants for their hair shape, color, balding and graying, and men were analyzed for beard, eyebrow and monobrow thickness.
By analyzing the hair traits of participants and comparing it with their genomes, the team was able to pinpoint genes that are associated with particular hair characteristics.
For the first time, the team linked a variant in the IRF4 gene to hair graying, finding that the presence of this gene variant correlated with hair graying among participants, particularly those of European ancestry.
It was already known that the IRF4 gene helps regulate the production and storage of melanin, influencing the color of skin, eyes and hair, but it had never before been linked to hair graying.
The researchers say understanding what role this gene plays in hair graying could pave the way for strategies to combat gray hair.
Co-lead study author Prof. Andrés Ruiz-Linares, of the Department of Biosciences at UCL, says:
"We have found the first genetic association to hair graying, which could provide a good model to understand aspects of the biology of human aging. Understanding the mechanism of the IRF4 graying association could also be relevant for developing ways to delay hair graying."
There are genes for curly hair, eyebrow thickness and monobrows, too
As well as a gene associated with hair graying, the team also uncovered a gene variant called protease serine S1 family member 53 (PRSS53) that influences hair curliness.
"The PRSS53 enzyme functions in the part of the hair follicle that shapes the growing hair fibre, and this new genetic variation, associated with straight hair in East Asians and Native Americans, supports the view that hair shape is a recent selection in the human family," says study coauthor Prof. Desmond Tobin, of the UK's University of Bradford.
What is more, the researchers pinpointed a variant in the gene EDAR that is responsible for beard thickness, a variant in the FOXL2 gene that influences eyebrow thickness, and a variant in the PAX3 gene that is linked to monobrow growth.
While the authors say their findings shed light on the genetic influence of hair traits, they admit that much more work is needed to identify the underlying mechanisms of the gene variants they discovered.
"The genes we have identified are unlikely to work in isolation to cause graying or straight hair, or thick eyebrows, but have a role to play along with many other factors yet to be identified," says Dr. Adhikari.
Last October, Medical News Today reported on a study in which researchers revealed how an existing class of drugs called JAK inhibitors could help restore hair growth.