MS is not considered a hereditary disease. The risk of getting MS is higher in relatives of a person with the disease than in the general population, especially in the case of siblings, parents and children. However, there is only around a 2% chance of a child developing MS when a parent is affected. It is important to consider that identical twins, who have the same genetic material, do not always both have MS. There is around a 20-30% chance of a twin of developing MS if their identical twin is affected. This is why researchers agree that MS is not simply a genetic disease.
The search for MS genes is important because their discovery will provide vital information on which biological mechanisms influence the disease. This will lead to a better understanding of what causes MS and to the development of new approaches to treatment and prevention.