Why red hair increases sun damage

It is well known that redheads with pale skin and freckles are prone to sun damage.  Now, new research from the Sanger Institute in Hinxton has shown how the gene associated with being a redhead not only increases the risk of developing skin cancer but also makes the tumour grow much faster.  What's more, this gene can also be carried by those without red hair, meaning many are unaware that they are at a greater risk. In fact - it is estimated that 25% of UK adults are carriers of the gene.  Redhead Claire Armstrong spoke to Dr David Adams to find out more...

David - What we were interested in in this study was exploring the link between variance in a gene called MC1R and this is the gene that's associated with being a redhead, and the effect that this has on the number of mutations that are found within a type of tumour called melanoma. A melanoma is a kind of skin tumor and they arise from cells called melanocytes which are found in the skin. Melanocytes are the cells which produce melanin and melanin is associated with tanning, so melanoma arises from those cells. If you're an individual who has no mutations in the gene MC1R, then you are someone who will tan but people who have one of these MC1R will freckle and they produce a slightly different form of melanin.

Claire - How do you know if you have these gene? I'm a redhead so I'm assuming that I have the gene but neither of my parents are redheads.

David - Right. So if you have two copies you've got a complexion like yours so red hair, probably pale skin and freckles. If you carry one copy, these people generally have pale skin and often freckles but they need not necessarily be redheads. It's generally the pale skin and freckles that would tell you carry one of these, what's known as an allele, which is a mutation in MC1R gene.

Claire - And are both of these groups in general more at risk of getting skin cancer?

David - If you are a redhead you're about four times more likely than the general population of develop melanoma. If you're one of these people who carries one of these variant form of MC1R, then you are about twice as likely. So this is further biological proof about exactly why that it is really the mutation number that is influenced by having one or two of the allele MC1R variants. So we looked in tumours that were established, so these were tumours that were removed when they were quite large. And what we found was that the number of mutations that you would find in an individual who carried one of these alleles equated to around the number of mutations that are in individuals without one of these alleles would get in 21 years.

Claire - And how did you study this? How did you study the increased mutations?

David - This was a big international collaboration and, fortunately, genome sequences had been generated for over 400 melanomas and these melanomas came from people all over the world, so we downloaded the data and reanalysed it.

Claire - What's actually going on then at a cellular level with these gene when you have the mutation in the genome? Do you know why it's giving rise to more mutations in the tumour than when you don't have the gene?

David - So its around the ability of individuals who carry these variants to produce that mature form of melanin, so the mature form is the darker coloured melanin. So the melanin, when you carry one of these variant forms of MC1R is not fully processed through to that darker form, and so you get a type of melanin that is red in colour and this particular type of melanin is less able to protect the cells of the skin from the effects of UV radiation.

Claire - I guess in the UK where we don't have very much sunshine unfortunately, actually 10 million people are deficient in vitamin D which we get from the sun, but then at the same time we don't want to be over-exposing ourselves to the sun. So what would be the best balance - we want to get some vitamin D!

David