Experts believe many people may carry a secret “ginger gene” which boosts the risk of skin cancer by as much as 21 years.

Generally associated with red hair and freckles, new evidence has shown that a variant of the MCR1 gene is carried by an estimated one in four people in the UK, leaving them open to an increased threat of cancer caused by exposure to ultraviolet (UV) rays from the sun.

The revelation may cause concern for a greater number of people in Ireland, which has an above average representation of people with red hair. Although the worldwide percentage stands between one and two percent, this rises to six percent amongst the Irish population.

Lead researcher Dr. David Andrews from the Wellcome Trust Sanger Institute in Hinxton, Cambridgeshire, England, explained: “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.”

According to scientists from the Wellcome Trust Sanger Institute and the University of Leeds in England, the MCR1 gene results in a greater risk of skin cancer because of a specific vulnerability to UV rays, and although this discovery mostly concerns people with red-hair and freckles, who have two copies of the MCR1 gene in their DNA, it also leaves people with different colored hair, yet who still carry one copy of the gene, more susceptible to developing skin cancer.

Experts warned that these carriers may not realise they are at risk as they will not automatically look like “easy burners.” Their natural hair color can range from brown to blond but they will still be prone to sun damage.

The MCR1 gene variant has previously been shown to be a deliberate genetic adaption that allows people with red hair, freckles and/or pale skin to absorb more vitamin D. The adaption is believed to have originally evolved in Ireland and Scotland where the cloudy and dull weather did not allow people enough opportunity to absorb the much-needed vitamin.

Our researchers show that red hair gene drives up skin cancer mutations - comparable to extra 21 yrs of sun exposure

— Sanger Institute (@sangerinstitute) July 12, 2016

Read more: Scientists confirm redhead gene evolved due to lack of sunlight

One of the main problems with the gene variant, however, is that it makes skin more likely to burn in the sun, with even a single copy of the variant shown to increase the chance of gene mutations associated with the most dangerous form of the cancer, malignant melanoma. The research found there is an average of 42 percent more dangerous mutations developed through sun exposure with the gene, with results estimating that these people will develop cancer-promoting mutations at the same rate as someone 21 years older.

The new evidence has been met with words of warning from cancer charities, eager to encourage those with redhair, freckles, or pale skin to protect themselves from skin damage.

“This important research explains why red-haired people have to be so careful about covering up in strong sun,” said Dr Julie Sharp, head of health and patient information at the charity Cancer Research UK.

“It also underlines that it isn’t just people with red hair who need to protect themselves from too much sun.

“People who tend to burn rather than tan, or who have fair skin, hair or eyes, or who have freckles or moles are also at higher risk.

“For all of us the best way to protect skin when the sun is strong is to spend time in the shade between 11am and 3pm, and to cover up with a t-shirt, hat and sunglasses,” Sharp advised.

“And sunscreen helps protect the parts you can’t cover; use one with at least SPF15 and 4 or more stars, put on plenty and reapply regularly.”

Red Hair Gene Drives Up Skin Cancer Mutations

— ScienceDaily (@ScienceDaily) July 13, 2016

This is the first time a link has been shown between the MCR1 gene and the development of mutations that cause skin cancer. Published in the journal “Nature Communications”, the new study analysed datasets of skin tumor DNA sequences collected from more than 400 people and confirmed that the number of mutations developed as a result of UV rays are linked with the “ginger gene.”

"All people, not just pale redheads, should be careful in the sun,” said Professor Tim Bishop, joint lead author and director of the Leeds Institute of Cancer and Pathology at the University of Leeds.

“This is the first study to look at how the inherited MC1R gene affects the number of spontaneous mutations in skin cancers and has significant implications for understanding how skin cancers form.

“It has only been possible due to the large-scale data available. The tumours were sequenced in the US, from patients all over the world and the data was made freely accessible to all researchers.

“This study illustrates how important international collaboration and free public access to datasets is to research.”

Read more: Redheads' secret of Tír na nÓg makes them look younger

H/T: The Irish Times