If genes alone were involved, mothers would pass the MS-related gene to their sons as often as their daughters, researcher George C. Ebers, MD, of the University of Oxford in the U.K. tells WebMD.
Ebers’ research suggests that the ability of environmental factors to alter gene expression -- a relatively new field of genetic study known as epigenetics -- plays a key role in multiple sclerosis and that this role is gender-specific.
The theory is that environmental influences such as diet, smoking, stress, and even exposure to sunlight can change gene expression and this altered gene expression is passed on for a generation or two.
“The idea that the environment would change genes was once thought to be ridiculous,” Ebers says. “Now it is looking like this is a much bigger influence on disease than we ever imagined.”
The study by Ebers and colleagues included 1,055 families with more than one person with MS. Close to 7,100 genes were tested, including around 2,100 from patients with the disease.
The researchers were looking for MS-specific alterations in the major histocompatibility complex (MHC) gene region.
They found that women with MS were 1.4 times more likely than men with the disease to carry the gene variant linked to disease risk.
A total of 919 women and 302 men had the variant in the MHC region, compared to 626 women and 280 men who did not have it.
The study was published online today, and it also appears in the Jan. 18 issue of Neurology.