EDINBURGH, Mar 07 (Reuters) - Their ginger hair and fair complexion have often made Scots the butt of jokes, but new research shows that these physical traits may also dangerously enhance genetic defects that lead to skin cancer.

The work carried out by Cancer Research Campaign scientists at Edinburgh University reveals that skin cancer may be caused by tiny genetic errors that prevent the body from patching up damage after the skin has been injured by ultraviolet rays.

When these genetic defects occur in someone of fair complexion, who already has a low natural resistance to the sun and is likely to suffer greater skin damage, it could be particularly cancer-promoting, according to the research.

"Our work shows that tiny mistakes in vital genes give people a two or three times greater risk of getting the disease. And this combined with a fair complexion is particularly dangerous," lead researcher David Melton said on Wednesday.

When genes are healthy, they spot sun damage in the skin and either repair it or stop the damaged cell from dividing. Cell division is the first step towards development of a cancerous growth.

Scientists hope to use their findings to develop a test to predict who is at greatest risk of developing malignant melanoma, a relatively rare type of skin cancer that is potentially life-threatening.

"If we can work out who has these tiny errors, we can tell them to take extra care in the sun and give them regular check-ups," Melton said.

The problems of skin cancer increase in the northern reaches of Scotland where people tend to have fairer complexions than those further south. The climate ensures that such individuals only encounter hot sun on holiday, and therefore have a greater tendency to burn.

In a 1997 study, an average 10.7 male Scots per 100,000 developed melanoma, compared with 7.8 in England and Wales.

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