Link to Susceptibility to Skin Cancer Found
By Karla Harby
PHILADELPHIA (Reuters Health) - Three normal variants of the melanocortin-1 receptor (MC1R) gene have been found to be strongly associated with susceptibility to skin cancers in the Australian population, according to research presented here at the American Society of Human Genetics annual meeting.
These variant alleles occur among people whose phenotype makes them appear similar in pigmentation, and may help explain why some people go on to develop melanoma, basal cell carcinoma, or squamous cell carcinoma during life in a sunny environment while others do not, said Dr. Richard Sturm of the University of Queensland, Australia.
The three variant alleles on the MC1R gene (R151C, R160W and D294H) are associated with fair skin, red hair and ultraviolet sensitivity, but one or two may appear in Caucasians with medium, olive or dark complexions, according to Dr. Sturm.
Among medium-, olive- or dark-skinned Australians, Dr. Sturm and colleagues found that those who carried one variant allele had a two-fold increased risk of melanoma, while those who carried two variants had a four-fold increased risk. In essence, Dr. Sturm explained, an unfavorable genotype can partly negate the protection normally provided by darker skin pigmentation.
How such genetic information might be used to augment current public health campaigns to limit sun exposure in Australia is unclear, he said. He emphasized that those whose genotype is relatively protective from sun exposure would be ill-advised to increase their time in the sun as a consequence. "I'd tell everyone, you've got to be sun aware," he said. "If you've got the variant, you have to be extra aware."
The Australian population has one of the highest skin cancer rates in the world, with a lifetime risk of developing melanoma of 1 in 17. This is attributed to the many fair-complexioned people from the British Isles who populate the country, parts of which receive sun exposure comparable to that of northern Africa.
