How often does multiple sclerosis occur?

Answer 1

In society, the risk of developing multiple sclerosis is about 1 in 750. If, however, you have a first-degree relative (parent, sibling, etc) who has MS, that risk increases to anywhere between 1 in 100 and 1 in 40.

But it's not all genetic. Take the identical twin example, twins who share the same DNA. If one gets MS, the risk of the other developing it is 1 in 4. If it were all genetic, the risk for the second twin would be 100%. The fact that it is 25% indicates that there are other factors involved, including geography, ethnicity, and that ever-elusive infectious "trigger" which seems to initiate the disease process.

Answer 2

Symptoms of MS usually appear between the ages of 20 and 50, although to a lesser degree it can affect children and significantly older adults.