Why More Women Get Multiple Sclerosis

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Why More Women Get Multiple Sclerosis: Genetics May Be at Work, Says

International Study By Miranda Hitti, WebMD Medical News

Jan. 27, 2005 -- Genetic differences between men and women could be the

reason why multiple sclerosis strikes more women than men.

About 400,000 people in the U.S. say they have MS, according to the National

Multiple Sclerosis Society. Worldwide, up to 2.5 million may be affected by the

chronic disease of the brain, spinal cord, and optic nerve.

In healthy people, nerve fibers are wrapped in a protective coating called

myelin. But MS inflames or destroys myelin, disrupting the flow of nerve

impulses. That can prompt problems with muscle control and strength, vision,

balance, sensation, and mental function.

MS is twice as common among women as it is in men. The reasons for the

gap aren't known.

Genetics seemed like a possible influence to Weinshenker, MD, and

colleagues. Genes and environment are probably both involved in the

development of MS, they write in the online edition of Genes & Immunity.

Weinshenker and his Mayo Clinic co-workers searched for clues about the

MS gender gap. They also enlisted help from experts in Northern Ireland,

Belgium, and Italy.

The international team studied the genes of MS patients in the U.S. They also

looked at gene patterns in people from Northern Ireland and Belgium, some

of whom had MS.

Women with MS were more likely to have a variation of a gene that produces

high levels of a protein called interferon gamma. Interferon gamma can

aggravate MS by promoting inflammation and tissue damage.

In the U.S. and Northern Ireland, men with the gene variation were more

susceptible to MS. That was also true for Belgian men, but the effect wasn't

significant there.

The gene variation was less common among men. " That might explain why

men are generally protected more from MS, " says Weinshenker in a news

release. Similar findings were reported by Italian researchers.

" Our finding isn't the whole genetic cause, but it's a helpful step that could

lead us to a more complete understanding of MS -- and ultimately, effective

treatment. It's also a very promising lead about gender differences that may

pertain to susceptibility of other diseases, too, such as rheumatoid arthritis. "

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SOURCES: Kantarci, O. Genes and Immunity, Jan. 27, 2005, online edition.

News release, Mayo Clinic. WebMD Medical Reference from Healthwise:

" Multiple Sclerosis: Topic Overview. " National Multiple Sclerosis Society.