Women are about twice as likely to develop multiple sclerosis (MS) as men and new research suggests that this may be related to variations in the gene for interferon (IFN)-gamma, a protein involved in the immune system.

“It’s a very promising lead about gender differences that may pertain to susceptibility to other disease too, such as rheumatoid arthritis,” Dr. Brian G. Weinshenker said in a statement.

IFN-gamma therapy is known to have an adverse effect on MS outcomes, and women are known to express more IFN-gamma than men. These observations led Weinshenker, from the Mayo Clinic in Rochester, Minnesota, and colleagues to evaluate the association between IFN-gamma gene mutations and MS risk in a study involving three different populations.

In populations of men in the US and Northern Ireland, gene mutations resulting in increased IFN-gamma expression were associated with a heightened risk of MS, the researchers report in the online issue of Genes and Immunity.

A similar, but non-statistically significant, trend was also observed among Belgian men.

So what does this have to do with the gender bias in MS? As it turns out, women are more likely to harbor these mutations than men, the researchers report.

“Our finding isn’t the whole genetic cause,” Weinshenker said, “but it’s a helpful step that could lead us to a more complete understanding of MS - and ultimately, effective treatment.

SOURCE: Genes and Immunity, January 27, 2005.