Redhead genes linked to skin cancer
12th July 2016 – Gene variants in people with red hair, pale skin and freckles have been linked to a higher number of gene mutations in skin cancers – and the researchers say this is comparable to having an extra two decades of sun exposure.
Redheads make up 1–2% of the world's population, but in the UK the percentage is even higher, at 4–6%. People who have red hair have two copies of a variant of the melanocortin 1 receptor (MC1R) gene. The variant, known as R allele, affects the type of melanin pigment your body produces and is responsible for red hair, pale skin and freckles – and a strong tendency to burn in the sun.
Exposure to ultraviolet light (UV), whether from the sun or sunbeds, damages DNA. It has been thought that having the pale skin that is typical of redheads could allow more UV to reach the DNA. This may still be one mechanism of damage, but the research published today in Nature Communications shows that the MC1R gene variant not only increased the number of spontaneous mutations caused by UV light but also raised the level of mutations found in skin cancers. This finding suggests that people with the MC1R gene variant could have biological processes in cancer development that are not solely related to UV.
Dr David Adams, joint lead researcher at the Wellcome Trust Sanger Institute, says in a statement: ""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."
The researchers looked at the data collected from the tumours of more than 400 people from around the world. Their analysis found that there was an average of 42% more sun-associated mutations in tumours from people who carry the gene MC1R variant.
The researchers say this could be equated to having an extra 21 years of sun exposure.
In a statement, Professor Tim Bishop, joint lead author and director of the Leeds Institute of Cancer and Pathology at the University of Leeds, says: "The tumours were sequenced in the USA, 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 data-sets is to research."
Not a redhead? – You still need to take care
The research also shows that even a single copy of a redhead-associated MC1R gene variant increased the number of mutations in melanoma skin cancer, the most serious form of skin cancer.
Dr Adams explains, "Unexpectedly… 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."