Although Multiple Sclerosis (MS) affects nearly two times more women than men, a recent study by the Mayo Clinic, the University of California at San Francisco, the University of California at Berkeley and Kaiser Permanente found that men are twice as likely to pass MS on to their offspring than women. MS affects about one in 1,000 people and the majority of the cases are women, Caucasians and people who live in temperate areas far from the equator. The average age of the onset of MS is between the ages of 30 and 33 and the average of diagnosis is 37 with 10% of cases being diagnosed as late as 50.
“Fathers with MS tend to have more children who develop MS than do mothers with the disease,” says Brian Weinshenker, M.D., Mayo Clinic neurologist and study investigator. “When we looked at a large population of MS patients, when there was a parent and a child who had MS in a family, the child with MS got the disease twice as often from the father rather than the mother.”
Although there have been many studies on MS linking environmental, genetic and viral causes for the disease, there is no consensus on an exact cause of MS. When it comes to genetic factors, the Mayo Clinic study also reveals that 15 percent of people with the disease have a family member within a generation who is also affected. Many scientists believe that the disease has a genetic component and there are extenuating environmental factors that can affect whether the disease expresses itself or remains dormant. So many people may be carriers of the disease but show no symptoms of having the disease whatsoever. Also, MS is a disease that affects everyone differently. The onset, severity and speed of the disease’s spread throughout the body varies widely from case to case.
So, if the genetic link is tenuous, why is it that men with a predisposition to the disease have double the chance of giving to it their offspring? “The hypothesis of the study is that men are more resistant to MS, so they need stronger or a larger number of genes in order to develop MS, and then pass these genes to their children,” says Orhun Kantarci, M.D., Mayo Clinic neurologist and lead author of the paper. The researchers believe that although they get the disease less frequently than females, males with the disease carry a larger “genetic load” of MS genes. Thus, the children of men who are predisposed to MS have a much higher genetic likelihood of the disease expressing itself than children born to female carriers.
The results of the Mayo Clinic study revealed that men transmit MS to their children 2.2 times more often than women in families where the father or mother of the child has MS. The study was conducted on 444 children of an MS-affected mother or father from 3,598 individuals.
