After rereading it I realized that the OP didnt say DF508 which is what my response was about LOL....
Although I guess that I could still say....no matter what characteristics are associated with mutation, there is still no way to know the outcome. Siblings who have identical mutations, compliance, environment can have completelt different outcomes.
As far as the actual mutation you ???, you would be better off posting in the AMBRY GENETICS THREAD of the Family Section. Steve from Ambry is great to us!