Why More Women Get Multiple Sclerosis
Genetics May Be at Work, Says International Study
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
Genetics seemed like a possible influence to Brian 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,
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
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