Azoospermia is the clinical term for the absence of sperm in the ejaculate. Azoospermia can be caused by disorders of sperm production within the testicle or disorders of sperm duct obstruction (blockage). The testicles produce sperm, but it is stored and transported in the epididymes and then the vas deferens. 1-2% of infertile men do not have a vas deferens on both sides, congenital bilateral absence of the vas deferens (CBAVD) and are thus obstructed. Men with CBAVD are azoospermic and infertile without advanced assisted reproductive technology.
CBAVD, in addition to a cause of male infertility, is also a manifestation of cystic fibrosis. Cystic fibrosis is an autosomal recessive genetic disorder of chloride transport and is more commonly associated with the ultimately fatal pulmonary disease. However, at least 50-80% of adult and otherwise healthy men with CBAVD will be found to have a gene defect in the CFTR region and will in-fact have a variant of cystic fibrosis.
Sperm production in the testicles is completely normal and unaffected in these men and with advanced sperm retrieval techniques and intracytosplasmic sperm injection (ICSI), they can have their own, biological children.
The DNA in the sperm of men with CBAVD will carry the CF mutation and the mutation may be passed on to their offspring after a successful ICSI. For this reason, their wives should be tested for CF mutations to ensure that they are not carriers as well.
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