New Delhi, Aug 13 : Having a bad hair day? Blame your genes, according to the first gene mapping study on human scalp hair whorls.
The study, published in the Journal of Investigative Dermatology, showed that hair whorl direction has a genetic basis, but also that it is affected by multiple genes.
Researchers from the Chinese Academy of Sciences in China identified four associated genetic variants that are likely to influence hair whorl direction.
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.
“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,” said lead investigator Sijia Wang, from Shanghai Institute of Nutrition and Health at Chinese Academy of Sciences.
“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,” Wang added.
For the genome study, the team included 2,149 Chinese individuals.
It was followed by a replication study in 1,950 Chinese individuals.
The results show 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.
Wang explained that previous studies proposed the hypothesis of associations between hair whorl patterns and abnormal neurological development, but no significant genetic associations were observed between hair whorl direction and behavioural, cognitive, or neurological phenotypes.
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