The MC1R gene variant can boost the risk of skin cancer by the equivalent of 21 extra years of sun exposure, say scientists.
Red-haired people such as Prince Harry, DJ and broadcaster Chris Evans and Simply Red singer Mick Hucknall, all have two copies of the variant, which causes a strong tendency to burn in the sun.
But even a single copy of the variant, found in many people without red hair and freckles, increases the number of gene mutations associated with malignant melanoma, the deadliest form of skin cancer, research shows.
Redheads are disproportionately represented in Scotland, making up around 13 per cent of the population compared with 1 per cent to 2 per cent around the world.
The MC1R variant affects the type of melanin skin pigment they produce, leaving them especially vulnerable to damage from the sun’s ultraviolet (UV) rays.
Lead researcher Dr David Adams, from the Wellcome Trust Sanger Institute, said: “It has been known for a while that a person with red hair has an increased likelihood of developing skin cancer but this is the first time that the gene has been proven to be associated with skin cancers with more mutations.
“Unexpectedly, we also showed that people with only a single copy of the gene variant still have a much higher number of tumour mutations than the rest of the population.
“This is one of the first examples of a common genetic profile having a large impact on a cancer genome and could help better identify people at higher risk of developing skin cancer.”
The scientists analysed data-sets of skin tumour DNA sequences collected from more than 400 people. They found an average of 42 per cent more sun-associated mutations in tumours from people carrying the MC1R gene variant.
UV rays, either from sunlight or artificially generated for sunbeds, damage DNA. People with red hair have a skin pigment that is thought to allow more of the rays to penetrate their DNA, potentially increasing the risk.
The new study confirmed the MC1R gene variant raised the number of spontaneous mutations in the skin caused by UV rays. Unexpectedly, it was also found to boost levels of other skin tumour mutations not related to UV exposure – suggesting involvement of the variant in cancer processes not driven by sunlight.