I found this question in the search summary of this blog.
I think the answer is a probable yes.
It has been estimated, although I’m not sure how these estimations are arrived at, that upto 90% of people with the common HNPP deletion are undiagnosed, misdiagnosed or possibly have no symptoms whatsoever. Although I think the last option is really a mixture of the first two.
I’ve seen some medical reports where the Doctors describe these cases of HNPP as having ‘Evanescent symptoms’
The dictionary definition of Evanescent describes this very neatly
: tending to disappear quickly : of relatively short duration