Scientists have identified a group of 124 genes that direct human hair pigmentation. While previous studies have shown that this feature is genetically controlled, it's the first time the specific genes have been pinpointed. This could not only allow us to better understand our own genome but it could also shed new light on skin, testicular, and ovarian cancer, as well as several other diseases.
We might not think about it too often, but hair plays a key role in our physical appearance -- okay, who am I kidding: everyone knows of that. Hair color (like skin color) is determined by two types of melanin. We already knew that melanin production and distribution have an overwhelmingly heritable nature (genetics accounts for almost 97% of color variation), but we didn't know which genes were responsible. Now, Pirro Hysi, Manfred Kayser, and colleagues, believe they've found the answer.
The scientists have analyzed DNA data from almost 300,000 people of European descent, including people with black, blonde, dark brown, light brown or red hair. By comparing their genetic information with their hair color, they were able to identify the genes responsible for hair pigmentation, including 100 were not previously known to influence pigmentation. Joint lead author Professor Tim Spector from King's College London said:
"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."
Interestingly, the work would have application in other fields, as some of the genes found to influence pigmentation are connected to several types of cancers, and others are related to Crohn's and other forms of bowel disease.
"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," Spector adds.
Additionally, the findings could also be useful in forensic analysis -- aside from improving our understanding of human pigmentation genetics, they pave the way for more accurate hair color prediction tests from DNA samples. In other words, forensic scientists might one day be able to tell someone's natural hair color based on DNA alone.
So far, researchers are very good at accurately predicting black and red hair, but blonde and brown hair are proving more challenging. The team also reports that, on average, women seem to have lighter hair than men, which suggests an association between sex and hair color.
The study "Genome-wide association meta-analysis of individuals of European ancestry identifies new loci explaining a substantial fraction of hair color variation and heritability" has been published in Nature.