Differences in the distribution, shape and colour of facial and scalp hair occur due to specific genetic variations identified in a paper published this week in Nature Communications. The results are based on a genome-wide association study (GWAS) of individuals from Latin America.
Human hair on the face and head varies significantly in appearance and distribution, both within and between populations, but the genetic basis of this variation has been poorly understood until now.
Andres Ruiz-Linares and colleagues perform a GWAS of over 6,000 Latin American individuals of mixed European, Native American and African ancestry. They identify ten genetic variations that influence natural variations in features of scalp hair - including shape, colour (such as graying) and balding - and of facial hair - including beard thickness, eyebrow thickness and synophrys (presence of a single eyebrow without a central gap). Although some genetic variations are shown to influence more than one hair feature (for instance, both hair shape and beard thickness), most of the variations for each of the facial hair traits did not overlap; for example, genetic variations associated with eyebrow shape may not necessarily affect other hair traits, such as balding. This study is the first to describe genes associated with hair graying, synophrys, and eyebrow and beard thickness.
These results may provide insight into the mechanisms influencing the shape and extent of growing hair fiber. In addition, identifications of potential genes and gene products involved in facial hair variation could provide potential molecular targets for mitigating or promoting hair growth.