Photo courtesy of King’s College London

A team of scientists, led by academics from King's College London and Erasmus MC University Medical Center Rotterdam, have discovered 124 genes that play a major role in determining human hair color variation.

The discovery sheds new light on our understanding of the genetic complexity underpinning variations in human pigmentation, and could advance our knowledge of conditions linked to pigmentation, such as skin, testicular, prostate and ovarian cancers. The new findings are also relevant for forensic sciences.

Although previous studies have found that a large percentage of hair color variation is explained by heritable factors, previous genetic studies only identified a dozen or so hair color genes. The new study, published today in Nature Genetics, largely explains the genetic knowledge gap.

In order to identify the previously unknown hair color genes, researchers analyzed DNA data from almost 300,000 people of European descent, together with their self-reported hair color information. The data was supplied by UK Biobank, 23andMe Inc., the International Visible Trait Genetics Consortium and their study partners.

By comparing the hair color of the group with their genetic information, stored at several million locations across the human genome, the team identified 124 genes involved in the development of hair color, of which more than 100 were not previously known to influence pigmentation.

The scientists also demonstrated that predicting hair color with this new genetic information is more accurate than with previously known genes.

"This work will impact several fields of biology and medicine. As the largest ever genetic study on pigmentation, it will improve our understanding of diseases like melanoma, an aggressive form of skin cancer," said joint lead author Tim Spector, from King's College London.

The genes that affect hair color also affect other cancer types, while other pigment genes affect the chances of having Crohn's and other forms of bowel disease.

"Our work helps us to understand what causes human diversity in appearance by showing how genes involved in pigmentation subtly adapted to external environments and even social interactions during our evolution. We found that women have significantly fairer hair than men, which reflects how important cultural practices and sexual preferences are in shaping our genes and biology."

"Besides substantially increasing our understanding of human pigmentation genetics in general, finding these new hair color genes is also important for further increasing the accuracy of hair color prediction from DNA traces in future forensic applications, which can help to find unknown perpetrators of crime," said joint lead author Manfred Kayser, from Erasmus MC.

"While the genetics of hair color is an interesting problem in itself, we hope that better understanding of the biology of melanin pigmentation will be applicable to studies of diseases that interact with pigmentation, such as skin cancer or vitiligo," added co-author Dr. David Hinds, from 23andMe.