Gene silencing?

[Angrydude00]

As far as the Gene silencing/epigenetic stuff goes, wouldn't that be worst case scenario? I could be wrong but that seems like it would be much harder, if not impossible to reverse. I hate to sound like a downer, but considering the length of time it takes to get better(which appears to be rare), I would assume that Gene silencing is the problem.
Then again, I don't know much about this stuff. Am I wrong? would it still be reversible even if it's a "genetic switch" being activated?