Photo by: Philippe Alès, via Wikimedia Commons, licensed under the Creative Commons Attribution-Share Alike 4.0 International license.
A genome-wide association study in a population of people with diverse ethnic backgrounds has for the first time identified a gene responsible for the greying of hair, confirming a genetic basis for the common sign of aging and potentially representing a target for treatment.
Published online in Nature Communications (March 1, 2016), the study looked at a sample of more than 6,000 individuals from across Latin America, recording aspects of both scalp hair (shape, colour, greying, and balding) and facial hair (beard thickness, monobrow, and eyebrow thickness), and comparing them genomically.
“We already know several genes involved in balding and hair colour but this is the first time a gene for greying has been identified in humans, as well as other genes influencing hair shape and density,” said lead author, Kaustubh Adhikari, PhD, in a press release from University College London (UCL). Dr. Adihikari is a research associate at UCL’s cell and developmental biology lab.
The identified gene, IRF4 is known to be involved in hair colour, but finding its association with greying required the wide range of backgrounds in the sample population, said Dr. Adihikari in the release.
“It was only possible because we analysed a diverse melting pot of people, which hasn’t been done before on this scale,” he said.. These findings have potential forensic and cosmetic applications as we increase our knowledge on how genes influence the way we look.” Past research into hair colour genetics has primarily used samples of people of European descent only.
In the study, DNA samples were collected from 6,630 volunteers from the CANDELA cohort recruited in Brazil, Colombia, Chile, Mexico and Peru. From those, a screened sample of 6,357 was used. Some 45% of sample subjects were male and 55% were female, and the sample population included individuals of mixed European (48%), Native American (46%) and African (6%) ancestry.
Schematic of seven hair features examined in the CANDELA study sample and the genes found to be associated with each (credit: K. Adhikari et al.). Photo courtesy of University College London
The authors found 18 gene-trait associations with genome-wide significance, of which ten were never before seen. The novel associations included genes tied to balding, as well as the first reported genes for hair greying, monobrow prevalence (PAX3), eyebrow shape (FOXL2), and beard thickness and hair shape (EDAR).
Dr. Andrés Ruiz-Linares, an honourary professor in UCL’s department of biosciences, who led the study, said in the release: “We have found the first genetic association to hair greying, which could provide a good model to understand aspects of the biology of human aging. Understanding the mechanism of the IRF4 greying association could also be relevant for developing ways to delay hair greying.”
According to the release, the findings of this study could be used to help develop forensic DNA technologies for building visual profiles based on an individual’s genetic makeup.