Purplelungs, You are right, there are about .5% of males with CF out there who have perfectly in tack vas defrens and no mucous clogging it. And actually, by all studies that have been done, men don't have the same mucus problem that women have, it's either that they do, or don't have a vas defrens- but 99.5% of them don't. Supposedly the DeltaF508 has been the mutation where 100% of the males have NO vas defrens, (like in my husbands case with a double deltaF508). There are some other mutations where men do have a vas defrens and are able to have children naturally, but thusfar there hasn't been a pattern for which mutations don't effect the vas defrens-only that the DeltaF508 certainly does. Also, some men who are diagnosed late in life, have been diagnosed ONLY because they have no Vas defrens. Which alerted a doctor to test for CF. So, in some men, that lack of Vas Defrens is the one and only effect CF has on them (lucky people!!)Thanks for bringing that up, I meant to elaborate on it a little more but got caught up in-well, you can see above. But I appreciate you taking the time to read the post.Julie (wife to mark 24 w/CF)