People with gene variants associated to red hair, pale skin and freckles are more likely to get a higher number of genetic mutations in skin cancers, scientists have revealed. The mutations associated with these variants – or alleles – could even produce an effect similar to that of an extra 21 years of sun exposure in people without these variants.
It is known that people with pale skin and red hair are more sensitive to sun exposure and have an increased likelihood of developing cutaneous melanoma, the most aggressive type of skin cancer.
However, a study published in Nature Communications is the first to show that the gene responsible for their hair colour and skin pigmentation is also linked to a greater number of melanoma mutations.
Some of these mutations can induce and sustain the growth of the tumours. Identifying them could lead to a better understanding of how melanoma form.
More red hair, more mutations
The researchers used data-sets of tumour DNA sequences collected from more than 400 people. They investigated whether people with red hair, pale skin and freckles – phenotypic characteristics linked to the R alleles in the MC1R gene – had more genetic mutations in their tumours.
They identified an average of 42% more sun-related mutations in tumours from people carrying the MCR1 R alleles. This figure is comparable to the expected mutational burden associated with an additional 21 years of age.
Sun exposure is thought to cause skin cancer because of ultraviolet (UV) light which damages the DNA. It is thought that the type of skin pigment associated with R alleles allows more UV to reach the DNA and thus facilitates the creation of tumours in people with red hair.
What this study now shows is that MC1R gene variants could also increase the risk of melanoma mutations, once these tumours have formed.
Protection for all
This does not mean that only these individuals with red hair should protect themselves from the sun.
As Dr Julie Sharp, head of health and patient information at Cancer Research UK, puts it: "This important research explains why red-haired people have to be so careful about covering up in strong sun. 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".