June 28, 2007 -- Men and women with multiple sclerosis (MS) share an equal risk of passing the disease onto their children, according to a new study.
The results contradict a study published last year that suggested men with multiple sclerosis were more likely to pass MS to their children than women.
In the current study, published in the journal Neurology, researchers found a nearly identical risk of transmission of the disease from either parent, with 9.41% of fathers and 9.76% of mothers passing MS to their children.
“Our study involved 16 times as many people as the previous published study,” says researcher George Ebers, MD, professor of clinical neurology at the University of Oxford, in a news release.
The exact cause of MS is not known, but MS risk is known to be increased in someone who has a close relative with MS.
Both Parents Pass MS
Researchers studied more than 3,000 Canadian families in which one parent had multiple sclerosis. Of the 8,401 children in those families, 798 had MS. The number of families with a mother with MS was 2,236 and the number of families with an affected father was 852.
When they compared the risk of mothers and fathers transmitting the disease to daughters and sons, they found both parents shared equal risk of passing on MS.
“We also found there were equal numbers of daughters and sons receiving the genetic risk of the disease from their parents,” says Ebers.
The previous study, published a year ago in the same journal, showed that men with MS were twice as likely to pass multiple sclerosis to their children. This is thought to be a result of the Carter effect, which holds that men are more resistant to MS because they carry a higher genetic load than women and therefore are more likely to pass the genetic risk of MS to their children.
But Ebers says these results show no evidence of that effect. Instead, researchers say the study suggests that environmental factors may have a stronger influence on the risk of developing multiple sclerosis than previously thought.
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