A genetic variant linked to red hair could slow wound healing, according to a study in mice. Researchers found that mice with inactive MC1R proteins, similar to those in redheads, recovered more slowly from wounds. An experimental drug showed promise in speeding up healing for other mice.
Hair color is largely determined by the MC1R gene, which encodes a protein controlling the balance between black-brown and red-yellow pigments in hair follicles. People with brown or black hair have active forms of this protein, while nearly all redheads carry mutations leading to less active or inactive versions. Blondes have more complex genetics in this regard.
The same MC1R protein exists in skin, where it exerts anti-inflammatory effects. Jenna Cash at the University of Edinburgh, UK, and her colleagues investigated whether this influences wound healing, which involves a controlled inflammatory response to remove microbes and dead cells. Excessive inflammation can impair recovery.
In their experiment, the team created 4-millimetre-wide wounds on the backs of black-haired and red-haired mice. The red-haired mice had completely inactive MC1R proteins. After one week, wounds in red-haired mice had shrunk by 73 per cent on average, compared to 93 per cent in black-haired mice.
Building on this, the researchers tested an experimental topical drug that enhances activity of active MC1R forms—but not inactive ones—on wounds in black-haired mice. Treated wounds shrank by 63 per cent after one week, more than double the rate of controls treated with saline. The drug reduced inflammatory immune cells. "If you’ve got a wound that’s half the size, I think patients would be quite thrilled about that, particularly after such a short time," says Cash.
Wound healing processes are similar between mice and humans, suggesting potential for treating chronic wounds, such as those in diabetes patients where high blood sugar prolongs inflammation. Most redheads have some MC1R activity and could benefit, though those with completely inactive forms would not. Drugs targeting MC1R are already used for conditions like erythropoietic protoporphyria, indicating a possible safety profile.
However, further studies are needed, says Kath Bogie at Case Western Reserve University in Ohio. She notes the drug's effects on infected wounds are unclear: "There’s a potential the drug could disrupt the response to infection, or it could have the opposite effect."
Cash emphasizes that redheads need not worry, as no human data exists yet and any effect may be minor. The team plans human trials soon. The findings were published in PNAS (DOI: 10.1073/pnas.2503308122).