People who have a gene known to cause red hair also have a much higher-than-usual risk of skin cancer —scientists said Tuesday they have a better explanation of why.
It’s bad news for redheads and even many people who don’t have red hair: The gene appears to raise the risk of cancer-causing mutations, even when they don’t go into the sun.
And while it takes two copies of the gene to give someone red hair, even people with just one copy have this extra risk.
In fact, some of the mutations linked with the gene, called MC1R, add up to the equivalent of an extra 21 years of life, the team reports in the journal Nature Communications. People with one of the “disruptive” versions of this gene have many more genetic mutations than people with less-dangerous versions, they found.
Red-headed people make up between 1 to 2 percent of the world’s population, but the rates are higher among people descended from Northern European stock.
“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,” said Dr. David Adams of Britain’s Wellcome Trust Sanger Institute, who helped lead the study.
So while everyone with melanoma has mutated tumor cells, people who have the MC1R gene have tumors just loaded with these mutations. And not all of them are mutations known to be caused by the sun’s radiation.
“Unexpectedly, we also showed that people with only a single copy of the gene variant still have a much higher number of tumor mutations than the rest of the population,” Adams added.
It might be possible to screen people for skin cancer risk by looking for the gene. “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,” Adams said.
The team studied more than 400 melanoma patients around the world who are taking part in a larger study of melanoma, the deadliest form of skin cancer.
Those with the so-called disruptive versions of MC1R had the mutations known to be caused by the sun’s rays, but also other mutations. The finding adds weight to what oncologists have long suspected – not all melanoma is caused by the sun’s rays.
“The take-home message for folks with red hair is that all the sun protection messaging that we've heard over the years — including being really aggressive about sun screen use, about choosing a broad spectrum sunscreen of SPF 30 or higher and applying every 2-3 hours with very heavy sun exposure — really is as important to them as anyone,” said Dr. Joseph Merola, a dermatologist at the Brigham and Women's Hospital, who was not involved in the study.
“We've known for many years now that redheads have a 10 to 100 times increase risk of melanoma, and even though they make up only 1 to 2 percent of the population, they make up to 16 percent of those with melanoma,” Merola added.
People with one version of the gene may not have red hair, but they often have light-colored eyes and light, easily freckled skin.
“There are many of us walking around with light skin, light-colored eyes for example,” Merola said.
“Those individuals are probably carrying some variants of these genes that do increase their risk beyond just having red hair, so it's a really important point that this applies to many more individuals than the 1 to 2 percent of the population who have red hair.”
Staying out of the sun won’t completely protect from melanoma, but it helps a lot.
“Sunscreen is the word of the day, and I think ‘pale is the new tan’ is the sort of take-home message,” Merola said.