Having a single copy of the 'ginger gene' may increase the risk of skin cancer, even among people who don't have red hair, according to a study.
'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 the Wellcome Trust Sanger Institute, joint lead researcher on the study.
'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,' he added.
People with two copies of the MCR1 variant known as the 'R allele variant' typically have red hair, and make up six percent of the UK population. Many more people – perhaps one quarter of the UK population – have a single R allele variant. They do not usually have red hair, but may have pale skin or freckles, and may burn easily in the sun. It had not previously been thought that they had as high a risk of melanoma as redheads.
In the study, which was published in Nature Communications, researchers examined tumour samples from 405 people with malignant melanoma – half of whom had one or two copies of the R allele variant. The tumours from people with one or two copies of the R allele variant had 42 percent more mutations than those from people without the variant.
The study authors say that one explanation for the similar rate of mutations in people with either one or two R allele variants is that people with two variants, and who have red hair and burn easily, are more likely to avoid the sun than those who are less sun-sensitive.
They also observed reduced DNA repair activity in the R allele variant tumours, suggesting a possible underlying mechanism for redheads' susceptibility to skin cancer. One particular DNA mutation seen in the R allele tumours was equivalent to an additional 21 years of skin ageing, the researchers reported.
Dr Julie Sharp of Cancer Research UK said: '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.'