Mockingbird,
You are usually head on with stuff but I have to correct you on this one. It is true that on rare occasions, carriers of the CF mutation do also have absense of the vas deferens- that by process of elimination is linked to being a CF carrier-make sense? So yes, her brother, even though he doesn't have CF (but I'm not too sure that's the case) could still have a "CBAVD" (congenital bilateral absense of the vas deferens) and not have CF.
CF is a much more complicated disease (aside from the health aspect) as far as the genetic breakdowns go, than it presents itself to be.
******And just a few educational tidbits, since this is kind of my soapbox:
-CBAVD casuse by the CF mutation creates an ABSENSE of the vas deferens, NOT a blocked/clogged or misformed vas deferens.
-65rosessamurai, Not to embarass you, but if your doctor said the testicles were of abnormal size (smaller testicles ARE normal in men with CF because the don't produce the HUGE numbers of Sperm that somebody with a vas deferens creates) there are medications that you can take. You can visit my website for more information, www.cysticfibrosismaleinfertility.com but you need to have the following tests:
TESTOSTERONE
FREE TESTOSTERONE
LUTHNIZING HORMONE (LH)
FOLLICULAR STIMULATING HOMRONE (FSH)
Depending on the restults of these tests, if any of your levels are abnormal they can put you on the following medications:
CLOMID
ARIMADEX
It takes 90 days for new sperm to fully mature so from the time you start taking the medication, the doctor should test you every 30 days to see if your hormone levels are progressing. If the levels are increasing, or if they were in the normal range to begin with, that's a HUGE indication that you ARE in fact producing sperm.
GOOD LUCK