Scientists Pinpoint Gene Behind Autoimmune Diseases

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"They probably have genes that predispose more toward autoimmunity in general and not specific disorders," Spritz said.

The team did a systematic genetic analysis of 656 persons from 114 extended families in the United States and United Kingdom who had multiple autoimmune diseases, including vitiligo. This led them to a number of genetic possibilities, but the "hottest" signal was a region on chromosome 17, which had shown up previously as possibly harboring a lupus gene in families who also had vitiligo.

A closer examination revealed a collection of variations in a specific gene, NALP1.

"We don't really know which one causes the disease, but we can use the variations that we see as flags or markers of variations," Spritz explained. "These could be the ones that cause the disease or tell us about the ones that do."

But NALP1 is probably only part of the picture.

"This can't be the whole story," Spritz said. "This is one of probably many genes that predispose to autoimmunity, but it looks like it may be involved in a pretty big way, which is why we were able to find it."

The gene is connected to the body's primitive immune system, which is involved with the earliest responses to outside attacks.

"It probably has a big effect, and it probably interacts in some complex way with other genes and other risk factors," Spritz pointed out. "We know a lot about this gene. It was not an anonymous gene that you would have to start from ground zero studying. We know that it's part of the surveillance system for attack by bacteria or viruses, part of the innate immune system."

"This work is really nice and elegant, and it's also provocative," Gregersen said. "It raises the issue of whether this gene might be involved in more common disorders."

He added that the research was a good example of "a successful, family-based approach to gene identification and an example of how new genes identified that way can raise new connections among different diseases."

More information

The U.S. National Institute of Arthritis and Musculoskeletal and Skin Diseases has more about autoimmune disorders.