Supplement: Ultraviolet Light and Lupus

Sunlight can worsen rashes and even trigger a flare-up of the disease in some people with lupus. It is well known that sun-sensitive lupus patients carry certain variants of the HLA genes, but those are not the ones that piqued the interest of Patricia Fraser, a molecular epidemiologist at Harvard Medical School. "Our hypothesis was that sun exposure causes damage to cells in such a way that it releases damaged DNA or damages the DNA itself," says Fraser. According to Fraser's scheme, the body recognizes the damaged DNA as foreign, and this generates an autoimmune reaction to the molecule. This would explain the presence of anti-DNA antibodies, a cardinal sign of lupus.

"We also knew that several members of the glutathione S-transferase (GST)...