Are you a tan­ner — or a burner?

Weekend Herald - - Science & Tech - Photo / 123RF

Sun­tan or sun­burn — even when com­pared to peo­ple who have a sim­i­lar skin tone we all re­spond dif­fer­ently to ex­po­sure to the sun. This nat­u­ral abil­ity of our body to pro­tect us from the sun’s harm­ful UV rays is de­ter­mined by ge­net­ics and new re­search out this week shows how un­der­stand­ing these tan­ning genes could po­ten­tially help re­duce our risk of skin can­cer.

We of­ten hear stay­ing out of the sun is im­por­tant for keep­ing our skin look­ing young and fresh as well as re­duc­ing our risk of skin can­cer.

How­ever, that lovely warm feel­ing of the sun on our skin is also crit­i­cal in the pro­duc­tion of vi­ta­min D in our body, which is es­sen­tial for keep­ing bones, teeth and mus­cles healthy.

When skin is ex­posed to the sun, a nat­u­ral pig­ment called melanin is used to re­duce the pen­e­tra­tion of the ul­tra­vi­o­let en­ergy into our cells. The melanin dark­ens in colour over time af­ter ex­po­sure to UV en­ergy and new melanin is pro­duced to help fur­ther pro­tect the skin.

Spe­cial cells called melanocytes cre­ate this pig­ment and push it out of the cell where it dark­ens the skin, giv­ing us a brown tan and also ab­sorb­ing the dam­ag­ing UV rays.

Over time our tan will fade as the dark­ened skin lay­ers are pushed up­wards by new cells that con­tain less of the brown melanin.

If our ex­po­sure to UV ra­di­a­tion ex­ceeds our body’s abil­ity to pro­tect the skin through this melanin tan­ning process, the ra­di­a­tion re­sults in per­ma­nent dam­age to the DNA of skin cells.

De­tect­ing this dam­age, the body tries to re­pair the area by prompt­ing the body to in­crease blood flow, which cre­ates warmth and a red­ness to the skin. The body also ac­ti­vates its in­flam­ma­tory re­sponse by send­ing

Dr Michelle Dick­in­son, cre­ator of Nanogirl, is a nan­otech­nol­o­gist who is pas­sion­ate about get­ting Ki­wis hooked on sci­ence and en­gi­neer­ing. Tweet her your sci­ence ques­tions @medick­in­son

im­mune cells to the dam­aged tis­sue, re­sult­ing in pain that it’s hoped will en­cour­age us to stay out of the sun for a while.

As in­di­vid­u­als, we all re­spond dif­fer­ently to sun ex­po­sure and the ge­netic ba­sis be­hind our re­sponse could help to pre­dict whether or not in­di­vid­u­als are more likely to be at risk of skin can­cer over their life­time.

New re­search pub­lished in the jour­nal Na­ture Com­mu­ni­ca­tions used ge­netic data from al­most 200,000 peo­ple of Euro­pean an­ces­try who re­ported whether their skin type burned or tanned eas­ily.

As one of the largest stud­ies of its kind look­ing at the ge­net­ics of sun­burn, the huge amount of data al­lowed sci­en­tists to com­pare the ge­netic vari­abil­ity of a di­verse group of peo­ple and see how these genes were re­spon­si­ble for pro­tec­tion from the sun.

It was al­ready known that peo­ple who tan eas­ily have more pro­tec­tion against DNA dam­age from the sun, and with smart lifestyle choices, such as pro­tect­ing them­selves from too much sun ex­po­sure, were at a re­duced risk of skin can­cer.

How­ever, this study was also able to iden­tify al­most all the genes in­volved in skin tan­ning, which in­cluded 10 new ge­netic re­gions not pre­vi­ously iden­ti­fied.

The re­sults sug­gest the de­vel­op­ment of skin can­cer can oc­cur via two path­ways: one de­pen­dent on skin pig­men­ta­tion and the other in­de­pen­dent of tan­ning abil­ity.

This new in­for­ma­tion could help sci­en­tists un­der­stand the ge­netic risk fac­tors in­volved in the most com­mon can­cer in our coun­try.

With so much new data, the po­ten­tial to cre­ate a sim­ple ge­netic test that pro­files a per­son’s bi­o­log­i­cal risk of de­vel­op­ing skin can­cer is pos­si­ble and could help in­di­vid­u­als to un­der­stand the se­ri­ous­ness of man­ag­ing their sun ex­po­sure.

A study has been able to iden­tify al­most all the genes in­volved in skin tan­ning.

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