Sometimes mocked, sometimes admired for their fiery manes, redheads hold a secret that geneticists have struggled to solve. An enigma that scientists have finally been able to overcome, as revealed in their work published this week in the Nature Communications journal.
There are eight of them. Eight genes are responsible for red hair colouring. While previously only one gene - MC1R - was suspected to be the cause of this, a team from the University of Edinburgh in Scotland has just highlighted the involvement of eight other genes.
A study of magnitude
To reach this discovery, geneticists analysed the genetic data of nearly 350,000 people. This information was collected as part of the UK Biobank study, a large-scale British program that began in 2006 and aims to better understand the role of genetic predispositions in the development of certain pathologies.
By comparing the genes of redheads with those of men and women with brown or chestnut hair, the researchers identified eight sequences that are specific to redheads. Among these genes, some would control MC1R, the only one that until now was thought to give redheads their flaming hair.
‘We are very pleased that this work has unveiled most of the genetic variations that contribute to hair colour differences among the population,’ says one of the contributors to the study, Albert Tenesa from the Roslin Institute at the University of Edinburgh.
Blondes and brunettes also studied
The geneticists’ work did not stop at the identification of the eight new genes involved in red hair colouring. They also discovered no less than 200 genes whose variants sometimes lead to blonde and sometimes brown hair colouring.
Of these 200 genetic differences, many do not involve variations in pigmentation, but rather the texture of the hair. This was an astonishing discovery for the researchers, who also identified the creators of the curls in some people’s hair, or on the contrary those who have straight hair.
‘This gives us a fascinating insight into what makes us such different people,’ concludes Melanie Welham, Executive Chairman of the Council for Biotechnology and Biological Sciences Research (BBSRC), one of the UK's seven research councils.