Having a bad hair day? Blame your genes!

The first gene mapping study on human scalp hair whorls not only shows that hair whorl direction has a genetic basis, but also that it is affected by multiple genes. Four associated genetic variants that are likely to influence hair whorl direction are identified, as reported opens in new tab/window in the Journal of Investigative Dermatology opens in new tab/window, published by Elsevier.

A hair whorl is a patch of hair growing in a circular pattern around a point specified by hair follicle orientations. As an easily observed human trait, scalp hair whorl pattern is typically defined by the whorl number (single or double whorl) and whorl direction (e.g., clockwise, counterclockwise, or diffuse).

Because atypical whorl patterns have been observed in patients with abnormal neurological development, understanding the genetic basis of whorl patterns may help unravel important biological processes.

The first genome-wide association study (GWAS) on human scalp hair whorls was performed among 2,149 Chinese individuals from the National Survey of Physical Traits cohort, followed by a replication study in 1,950 Chinese individuals from the Taizhou Longitudinal Study cohort.

Lead investigator Sijia Wang, PhD, Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences, explained, "We know very little about why we look like we do. Our group has been looking for the genes underlying various interesting traits of physical appearance, including fingerprint patterns, eyebrow thickness, earlobe shape and hair curliness. Hair whorl is one of the traits that we were curious about. The prevailing opinion was that hair whorl direction is controlled by a single gene, exhibiting Mendelian inheritance. However, our results demonstrate that hair whorl direction is influenced by the cumulative effects of multiple genes, suggesting a polygenic inheritance."

The study identifies four associated genetic variants (at 7p21.3, 5q33.2, 7q33, and 14q32.13). These genetic variants are likely to influence hair whorl direction by regulating the cell polarity of hair follicles, with cranial neural tube closure and growth also potentially playing a role.

Caption: Genome-wide association studies of hair whorl direction identified four significant signals. (a) Patterns of whorl direction. (b) Manhattan plot and quantile-quantile plot from the discovery and replication cohorts (Credit: Journal of Investigative Dermatology).

Professor Wang continued, "While previous work proposed the hypothesis of associations between hair whorl patterns and abnormal neurological development, no significant genetic associations were observed between hair whorl direction and behavioral, cognitive, or neurological phenotypes. Although we still know very little about why we look like we do, we are confident that curiosity will eventually drive us to the answers."

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Notes for editors

The article is “GWASs Identify Genetic Loci Associated with Human Scalp Hair Whorl Direction,” by Junyu Luo, He Huang, Hui Qiao, Jingze Tan, Wenyan Chen, Manfei Zhang, Andrés Ruiz-Linares, Jiucun Wang, Yajun Yang, Li Jin, Denis J. Headon, and Sijia Wang (https://doi.org/10.1016/j.jid.2022.11.026 opens in new tab/window). It appears online in advance of the Journal of Investigative Dermatology, volume 143, issue 10 (October 2023), published by Elsevier.

The article is openly available at https://www.jidonline.org/article/S0022-202X(23)01995-4/fulltext opens in new tab/window.

Full text of the article is also available to credentialed journalists upon request. Contact Theresa Monturano, at +1 215 239 3711 or [email protected] opens in new tab/window to request a PDF of the article. Journalists wishing to interview the authors should contact [email protected] opens in new tab/window.

About Journal of Investigative Dermatology

The Journal of Investigative Dermatology  opens in new tab/window(JID) is the official journal of the Society of Investigative Dermatology and the European Society for Dermatological Research. JID publishes high impact reports describing original research related to all aspects of cutaneous biology and skin diseases. Descriptions of important findings that result from basic, translational, or clinical research are published. Clinical research can include, but is not limited to, interventional trials, genetics studies, epidemiology, and health services research. www.jidonline.org opens in new tab/window

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