The genes involved in the devastating immune system disease Lupus, which affects 50,000 people in the UK, have been identified.
Skin lesions are one of many symptoms of lupus
A team led by London's Imperial College examined the genetic makeup of 3,000 women, publishing their findings in the journal Nature Genetics.
The suspect genes could open the door to research into new treatments.
Charity Lupus UK said that the find might one day lead to a test to speed up the diagnosis of the condition.
Lupus is a complex condition, mostly affecting women, which frequently causes skin rash, joint pains and fatigue, and which can also lead to inflammation of the kidneys and other internal organs.
It happens when the person's own immune system starts launching attacks on healthy tissue, and the only current treatments aim to suppress the immune system to reduce this.
The study looked at 720 women with the illness, and compared their genes with those of 2,337 who are free of the disease.
This revealed three candidate genes with strong links to Lupus, and a few others with weaker links to the disease.
One of the strong candidates, the ITGAM gene, is known to play a role in the immune system.
The other genes identified were more surprising to the experts, but could, they say, hold the key to developing more effective therapies.
Professor Timothy Vyse, from Imperial College London, and one of the authors of the study, said: "Living with Lupus can be really tough.
"We currently can treat the disease by suppressing the immune system, but we urgently need to understand in much more detail what goes wrong with the immune system so that we can design better treatments.
"This study represents a milestone in progress towards unravelling the secrets of the disease.
He said that he was hoping to collect further blood samples from other Lupus patients to confirm the results, and asked volunteers to get in touch.
Jane Dunnage, the chairwoman of charity Lupus UK, and herself a Lupus patient, said that one advantage of the discovery of Lupus-related genes might be to speed up diagnosis.
"Every patient is different, and you often have different symptoms such as rashes or joint pain which could apply to a lot of conditions, so it can be years before a diagnosis of Lupus is finally made.
"If we knew what the genes were that are involved, in theory that could be done much more quickly.
"This is a really welcome development for Lupus patients."