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Hair Whorl Direction Linked to Multiple Genes in GWAS

In a letter to the editor in the Journal of Investigative Dermatology, a Chinese Academy of Sciences-led team describes genetic variants with apparent ties to human hair whorls — circular patches of scalp hair present in a defined number and directionality that appear during development and may be distorted in individuals with altered neurological development. The researchers initially focused on variants that coincided with hair whorl patterns in a genome-wide association study involving 2,149 Chinese individuals from a National Survey of Physical Traits study, focusing on clockwise or counter-clockwise whorls in individuals with no more than one hair whorl apiece. After bringing in data for another 1,950 individuals from a longitudinal study in China for validation and meta-analyses, the authors were left with four hair whorl direction-related loci that were subsequently assessed with fine mapping analyses to narrow in on causal genes and variants, including a ARL4A gene quantitative trait locus that was tested by single-cell sequencing in a mouse model. "[T]his study reveals that hair whorl direction is a polygenic trait and identified four associated loci," they write. "The functions of the genes identified suggest that cell polarity and cytoskeletal structure in HF development and cranial neural tube closure and growth may influence HF orientation and contribute to whorl directionality."