Look what I found! I was doing some research on fatigue from systemic autoimmune disease for one of our members from the Sjogren's group, when I saw mention of mitochondrial disease, in attempting to define that, up pops this article from NIH. So now I understand WHY it is so important for the genetic tests to be done.
This is very interesting. IIRC, some subtypes of CMT do involve the mitochondria (CMT2 and CMT4). A genetic test is certainly a good thing if there's no familial history of CMT and CMT symptoms are present.