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Children of MS Dads More Likely to Inherit Disease

Men with multiple sclerosis seem to be more than twice as likely to transmit the disease to their children as women with this disease, say researchers from the Mayo Clinic.

This finding may come as a surprise to some because multiple sclerosis is more than twice as common in women as in men. But researchers say this difference in prevalence may have something to do with a father's higher chance of passing genetic risk factors for the disease to his offspring.

Multiple sclerosis is a degenerative nerve disorder that affects the brain and spinal cord. It is estimated that nearly 1 in 1,000 people will develop this disease that slowly attacks the nervous system and causes difficulty walking, pain, fatigue and depression among other symptoms. It is believed that both genetics and the environment play a part in its development; about 15 percent of patients with multiple sclerosis have at least one family member with the disease.

"A combination of genes and unknown environmental factors work together to cause multiple sclerosis," said lead study author, Dr. Orhun Kantarci, neurologist at the Mayo Clinic.

So, determining how parental inheritance plays a part in multiple sclerosis transmission may help researchers better understand how the disease works.

For the study, researchers from the Mayo Clinic in Rochester, Minn., looked at 444 children with multiple sclerosis whose mom or dad also had multiple sclerosis. The children came from 206 different families. Comparing the number of children whose father had multiple sclerosis to the number of children whose mother had multiple sclerosis, the researchers found that a father with this disease is 2.2 times as likely to have a child also with the disease. The results of the study were published in the journal Neurology.

"Fathers with MS tend to have more children who develop MS than do mothers with the disease," said study author, Dr. Brian Weinshenker, neurologist at the Mayo Clinic.

The researchers believe that this finding sheds some light onto how multiple sclerosis may be caused by slightly different factors in men and women. They say that since men are less likely to develop multiple sclerosis than women, those who do have the disease tend to also have more MS-prone genes, making them more likely to pass all or some of these genes to their children.

"The hypothesis 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," said Kantarci.

While the results of this study might seem to dissuade men with multiple sclerosis from having children, Kantarci said that these findings shouldn't change anyone's plans.

Men and women with multiple sclerosis should still speak with a genetic counselor prior to starting a family, but since the risk of having a child is already high no matter which parent has multiple sclerosis, a genetic counselor will likely not say anything different to a family in which the father has the disease, said Kantarci.