my son.

hello, I'm new to this site and I need support.  My son has had a collection of diagnoses and some of them have changed.  I was just told by the allergist that he might have Mito and that I should look in to it and get ready.  I know of some people with Mito and they don't know what to make of it since their kids and so severe vs my son that is not.  My question is can symptoms change and diagnoses come and go with Mito?  Should I be concern and where do I turn?