By performing genome-wide analyses across hair colors, researchers at the University of Edinburgh, UK, have discovered eight new genetic variants that contribute to red hair.
Morgan et al discovered eight new genes linked to red hair. Image credit: Pezibear.
Although almost everyone with red hair has two copies of the red-haired version of a gene called MC1R (melanocortin 1 receptor), not everyone carrying two red-haired versions is a redhead.
Scientists knew there must be other genes involved but these have mostly remained a mystery until now.
Now University of Edinburgh professors Ian Jackson and Albert Tenesa and their colleagues have looked at DNA from 343,234 people who had taken part in the UK Biobank study.
The researchers focused on people of European descent because they have greater variation in hair color.
Comparing redheads to people with brown or black hair, they identified eight previously unknown genetic differences that are associated with red hair.
The team also looked at the functions of the genes they identified and found that some of them work by controlling when MC1R is switched on or off.
“We are very pleased that this work has unraveled most of the genetic variation contributing to differences in hair color among people,” Professor Tenesa said.
In addition to the redhead genes, the scientists uncovered differences in almost 200 genes associated with blondes and brunettes.
“There is a gradient of color from black, through dark brown to light brown and blonde, which is caused by increasing number of genetic differences in these 200 genes,” they said.
“We were surprised to find that many of these 200 genetic differences were associated with hair texture rather than pigmentation.”
“Others are involved in determining how the hair grows — whether curly or straight, for example.”
The findings appear in the journal Nature Communications.
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Michael D. Morgan et al. 2018. Genome-wide study of hair colour in UK Biobank explains most of the SNP heritability. Nature Communications 9, article number: 5271; doi: 10.1038/s41467-018-07691-z
