One in 200 people have vitiligo
People with the skin disease vitiligo may have natural protection against skin cancer, a study suggests.
The condition, affecting one in 200, causes pale skin patches that lack pigment and burn easily - leading to an assumed increased risk of skin cancer.
But the University of London study of 4,300 people identified a common gene mutation that both increases the chance of vitiligo and cuts cancer risk.
The findings are reported in the New England Journal of Medicine.
However, study author Professor Dot Bennett, from St George's, University of London, still warned: "Although this may provide some consolation for people with vitiligo, they should still be careful in the sun. As they know, they sunburn quickly, and a lower risk of cancer doesn't mean zero."
The findings, reported in the New England Journal of Medicine, emerged from genetic testing of 1,514 patients with vitiligo and 2,813 without.
Seven genes in total were identified that were linked to vitiligo.
Some 70% of the general population had the combination that increases the risk of vitiligo while reducing the risk of malignant melanoma, the most serious form of skin cancer.
The remaining 30% had a different version that raises melanoma risk while lessening the chances of vitiligo.
Although everyone has one of the two variants, neither guarantees that either vitiligo or melanoma will actually develop. Likewise, neither guarantees protection, the study added.
The genes identified were already associated with auto-immune conditions such as type 1 diabetes, rheumatoid arthritis and lupus.
This prompted suggestions the research may even lead to improvements in treatment for vitiligo.
There is currently no cure although the condition can be managed through steroid creams and treatment with ultraviolet light.
But the study said future therapy may involve some element of "calming down immune response".