Fathers may be more likely to transmit MS risk.

MS is not directly hereditary. But people with MS in the immediate family do have a higher chance of developing it. While the average person in the United States has about one chance in 750 of developing MS, the risk for a person who has a parent with MS increases to about one in 40.

A new study of families with more than one person with MS suggests that when the father has MS, a child may be more than twice as likely to develop the disease than when the mother has it.

Orhun H. Kantarci, MD, who led the Mayo Clinic team, suggested that if men are more resistant to MS, then those men who actually develop the disease must have more susceptibility genes in order to overcome gender-related resistance. Therefore, they might pass on a larger number or stronger susceptibility genes to their children.

Dr. Aaron Miller, the National MS Society's Chief Medical Officer, told InsideMS that, while these findings may be of interest to scientists searching for MS genes, "they don't change genetic counseling advice for families with a parent who has MS."

The study was published in the July 25, 2006, issue of Neurology, and was funded by the Society, the National Institutes of Health, and the Mayo Foundation.