I agree with Chaggie, it could be that the other mutation hasn't been identified yet. Over the years, over 1300+ mutations have been discovered, with more being discovered currently. So, if it hasn't been done, I agree that the Ambry full genetics panel should be done to see if you have a rare mutation hiding in your CFTR gene. Jenn <img src="i/expressions/face-icon-small-smile.gif" border="0">