@lileitak: it depends on the diagnosis. Some have it because of the cystic fibrosis which will pass onto the child. These people normally don't have to seek for donation because they are just born without van deferen (obstructive azoo). Some with non-obstructive can be caused by chromosome abnormality like klinefelter or other type of chromosome micro-deletion. However, one of these type has a pretty high success rate of retrieving sperms through the surgery. Thus, no need for donation either. With other without a reason, like most of our azoo DH here, it is just an one off unfortunate event. No one in the family even has low count. It is kind of strange if you ask me. Azoo people with a reason have a higher chance to produce offspring which potentially can pass on to the male child, those without reason has zero chance. However, for those unknown case, it must be a genetic misfired somewhere as well just unknown.