April 13 (iVillage Total Health) -- People who battle debilitating autoimmune disorders such as lupus, thyroid disease and psoriasis may have the same gene that causes vitiligo, a skin disorder that causes pale patches of skin.

Vitiligo is a relatively common skin condition affecting 2 million to 5 million people in the United States and 40 million to 50 million people worldwide, according to the National Institutes of Health (NIH). Patches of the skin lose all pigmentation (color) and become milky-white. Lack of pigmentation may occur anywhere on the body, including the hair and inside the mouth but is most common on the arms, legs and face. The exact cause of vitiligo is not known, but the most prevalent theory is that it is an autoimmune disorder, where antibodies (cells that normally fight infection) attack and kill skin pigment cells. Past research has revealed there may be a genetic link to the condition.

Researchers from Great Britain and the University of Colorado at Denver conducted genetic testing on two groups of families with vitiligo and other autoimmune disorders between 1996 and 2005. They found that people with vitiligo had an increased risk of developing other autoimmune disorders and their relatives -- even those who didn't have vitiligo -- were also at risk of developing autoimmune conditions.

The genetic testing revealed that a gene called NALP1 was implicated in development of the diseases. NALP1 is a key player in the immune system's response to viral and bacterial infection. The gene is part of the alert systems that warns of attack.

"What's really exciting for us is that NALP1 hasn't been specifically implicated in autoimmune diseases before," Dr. Richard Spritz, the study's lead investigator, said in a press release. "Since NALP1 appears to be part of our body's early-warning system for viral or bacterial attack, this gives us ideas about how to try to discover the environmental triggers of these diseases. This finding may also open up new approaches to treatment, possibly for many different autoimmune diseases."

More than 80 conditions are recognized as potential autoimmune diseases, including type 1 diabetes and rheumatoid arthritis. Together, these diseases impact between 14 million and 24 million people in the United States, according to the NIH. Overall, autoimmune disorders may affect between 5 and 8 percent of the United States' population, according to the Centers for Disease Control and Prevention. Experts said the conditions appear to be occurring more frequently today than in past decades.

"All diseases are complex, the result of different genes and environmental risk factors acting together in concert," Spritz added "But if NALP1 turns out to be one of the major genes involved in numerous autoimmune diseases, and if we can interrupt its negative effects, we may have the chance to treat many different chronic autoimmune disorders like vitiligo, lupus and psoriasis and perhaps eventually eliminate them altogether."

The research was partially funded by the NIH, the Vitiligo Society and the National Vitiligo Foundation. The study appeared in the March 22 issue of The New England Journal of Medicine.

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