Multiple Sclerosis symptoms explained in terms of Penetrance

[ritalinn]

Multiple Sclerosis is a neuro-degenerative disease. Yet not everyone who has the genes for it actually has clinical symptoms. And if they do, the symptoms are sometimes severe, or sometimes mild. How can you explain this in terms of Penetrance and Expressivity?

[Darby]

There probably is a genetic influence on MS (even in identical twins, there's less than a one-third chance that if one has it the other will), but there is likely no "gene" for it, so I'm not sure the question makes any sense.

[MrMistery]

this has "homework" written all over it. do you know what penetrance is?