The appearance of human eyebrows is not just a matter of grooming but is in the genes. Eyebrow thickness, as any other appearance trait, is highly heritable. Thus far, genetic knowledge on eyebrow thickness has been very limited and solely restricted to non-Europeans. The first genome-wide association study on eyebrow thickness in Europeans identified new genes as well as rediscovered some of the genes previously identified in non-Europeans.
Peng et al. demonstrate that eyebrow appearance has partly the same and partly different underlying genes in people from different parts of the world. Image credit: Zehra Soy.
“Natural variation in eyebrow thickness is one of the most conspicuous facial features,” said lead author Dr. Manfred Kayser, a researcher at the Erasmus MC University Medical Center Rotterdam and co-chair of the International Visible Trait Genetics (VisiGen) Consortium, and his colleagues.
“Understanding its genetic basis is of broad interest and has implications for dermatology and other fields.”
Previous studies were performed among Latin American and Chinese individuals, establishing four eyebrow thickness-associated genetic loci.
Because no European eyebrow thickness genome-wide association study had been reported, researchers did not know whether the genetic eyebrow thickness effects described in non-Europeans persist in Europeans, or whether there are European-specific genetic loci involved in eyebrow thickness, or both.
“Despite the immense efforts in mapping genes underlying human complex traits, we still know much more about the genes that make us sick than about those behind our healthy looks,” Professor Kayser said.
“For the first time, we performed a gene mapping study on eyebrow thickness variation in Europeans.”
“Previous genetic knowledge on eyebrow thickness was limited and solely restricted to non-Europeans.”
“We discovered new genes involved in eyebrow variation in Europeans and rediscovered some of the genes previously identified in non-Europeans.”
The researchers analyzed data from 9,948 individuals representing four groups of European ancestry.
They not only discovered three previously unreported genetic loci associated with eyebrow thickness, but also rediscovered two of the four genetic loci previously found in non-Europeans.
Two other genetic loci previously reported in non-Europeans had minimal effects in Europeans, due to very low allele frequencies in Europeans.
“Our study significantly improves the genetic knowledge of human eyebrow appearance by increasing the number of known genes from four to seven and delivers new targets for future functional studies,” Professor Kayser said.
“By having demonstrated that eyebrow variation is determined by both shared and distinct genetic factors across continental populations, our findings underline the need for studying populations of different ancestries for unveiling the genetic basis of human traits, including, but not restricted to, physical appearance.”
The results appear in the Journal of Investigative Dermatology.
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Fuduan Peng et al. Genome-wide association studies identify DNA variants influencing eyebrow thickness variation in Europeans and across continental populations. Journal of Investigative Dermatology, published online April 19, 2023; doi: 10.1016/j.jid.2022.11.026
