Scientists have located sections of DNA that appear to play a role in controlling whether an individual’s skin burns or tans, which has laid the groundwork for genetic tests that could predict people’s responses to sunlight. 

This is the largest genetic study of its kind, using data from nearly 200,000 people. It is thought that the discovery could also help researchers understand the onset of skin cancer – which affects 150,000 new patients in the UK every year. The results of the study were published in the journal Nature Communications

Lead author of the study, Dr. Mario Falchi, a researcher at King’s College London, commented that “a good percentage” of the sunburn genes they identified were also involved in skin cancer. She went on to say that their work also helped explain the phenomenon familiar to many of the friend with a similar complexion who turns a different colour when tanning. 

Darker-skinned people are naturally more resistant to the harmful effects of sunlight, but the scientists’ work suggested there are genetic factors besides natural skin colour that can protect people from the sun. 

“Some of these genes involved in skin cancer probably have nothing to do with pigmentation,” he added. “This may explain why for example the person next to you in the park gets completely red, and you get tanned, and you have exactly the same skin colour. There is variability for people with the same pigmentation.” 

The research was undertaken using a large quantity of genetic data taken from the UK Biobank, which contains information about people’s health and wellbeing that can be used by researchers. Through using such a resource, the researchers had access to genetic information belonging to tens of thousands of people of European ancestry who had self-reported on their tendency to tan or burn. This information ranged from those who said they always burned and never tanned to those who tanned without burning. 

Later, the scientists explored the genetic variability between all of these people and ultimately focused on 10 new genetic regions that appeared to be linked with tanning. 

“By using a very large sample size we are able to identify almost all the genes involved in determining a particular trait – which is very interesting because once this can be defined you can develop some real genetic prediction tests,” added Dr. Flachi. 

But, he did note that the issue sunburn is easy to solve without genetic tests, as it is essentially an issue of behaviour change. “Getting tanned is a trend that started in the 1920 – before no one wanted to be tanned they wanted to be as white as possible,” he said. 

Despite this, Dr. Falchi did state that regardless of genetics, no one needs to expose themselves to excess levels of sunlight, beyond the amount needed to avoid vitamin D deficiency.