Although the cause of multiple sclerosis remain unknown, scientists theorize that it may have something to do with either genetic or environmental factors. A recent study showed that environmental factors may play a major role to the disease.
Researchers at University of California in San Francisco conducted an intensive gene analysis on a pair of identical twins in which one has MS and the other does not. They found out that there are no genetic differences that could explain why one sibling had the disease and the other did not. The researchers also did not find any differences in the epigenome, or mechanisms that change the way genes are expressed aside from changes in DNA, that would explain the disease of one twin.
However, the researchers do not confirm with finality that genes have nothing to do with the disease, as the identical twin without MS has a 30% increased risk that she would acquire the disease, compared to an increased risk of only 5% for a nonidentical twin.
It is still unknown what environmental factors contribute to causing MS. One prominent theory is that a virus triggers the immune system reaction that leads to the disease. Other possible factors include smoking and vitamin D deficiency.
Source: Los Angeles Times