Although most people associate melanoma with exposure to UV light, through excessive sunbathing for example, the disease can be inherited indicating that faulty genes are also partly to blame. Genetic risk factors also affect the likelihood of individuals suffering from non-inherited, or sporadic, melanoma.

To identify these risk factors, researchers from the University Hospital in Tuebingen took blood samples from 450 healthy volunteers, and 500 people who had been diagnosed with malignant melanoma, from which they could extract DNA. In collaboration with Genefinder Technologies Ltd., Munich, Germany and Sequenom Inc., San Diego, USA, the researchers studied the DNA samples, looking for slight differences in the genes between people with melanoma skin cancer and people with no cancers at all. To do this they screened more than 25,000 sites across the whole genome, which are known to vary naturally between different people.

The researchers identified a gene called BRAF that contains several sites of natural variation. Some variants were more likely to be found in people who suffered from melanoma than in those that did not. But, when the data was separated by sex, it appeared that the variants only conferred a higher risk of suffering from melanoma on men who carried them.

At present, men have a 1 in 58 chance, and women a 1 in 82 chance of developing the disease in their lifetime. The researchers write: "BRAF may be one explanation of why males have an increased lifetime incidence of melanoma compared to females".

Until now, the best-known risk factor for melanoma was if you had a mutated copy of the gene CDKN2A. This gene could explain about 25% of the
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BioMed Central
26-Nov-2003