Multiple sclerosis (MS) is not considered to be an inherited disease, but there is increasing evidence that genes play some role in who gets it and who doesn’t. Researchers have found that one specific gene region in humans contains some information that may eventually help unravel the mystery of who gets MS, and why.
Studies with twins provide the best support for the idea that genes have an impact on the disease. Identical twins share the same genetic makeup, or DNA. If one identical twin develops MS, the other has about a one-in-four chance of developing it as well. Fraternal twins, though born together, come from different eggs and so have different final DNA patterns. Although they have the same number and type of genes, the actual code for each gene is slightly different in one fraternal twin compared to the other. In these twins, if one develops MS the other only has a one-in-20 to one-in-50 chance of getting the disease.
Other studies have shown that brothers and sisters of people with MS have about the same risk as fraternal twins. Parents and children have lower risks. These twin and family studies show that the more the genes look alike, the more likely it is that the disease occurs. While genes don’t hold all the answers, they may contribute to the story.
If not genes, then what? Most likely, MS has many contributing causes. Multiple different genes may combine or fail to work together, the environment may contain things that react with some peoples’ genes and not others’, or there may be viruses or other as-yet-unknown biological agents that contribute to the development of MS. We hope that medical research will soon help us further unravel the mystery of who gets multiple sclerosis and why.