Congenital absence of the vas deferens

Congenital absence of the vas deferens (CAVD) is a condition in which the vasa deferentia, male reproductive organs, fail to form properly prior to birth. It may either be unilateral (CUAVD) or bilateral (CBAVD).

Presentation
The vas deferens helps connect the sperm-producing testicles to the penis. Therefore, men who are missing both vas deferens are typically able to create sperm but are unable to transport them appropriately. Their semen does not contain sperm, a condition known as azoospermia.

Causes
There are two main populations of CAVD; the larger group is associated with cystic fibrosis and occurs because of a mutation in the CFTR gene, while the smaller group (estimated between 10 and 40%) is associated with Unilateral Renal agenesis (URA). The genetic basis of this second group is not well understood.

Mutation of the CFTR gene is found to result in obstructive azoospermia in postpubertal males with cystic fibrosis. Strikingly, CAVD is one of the most consistent features of cystic fibrosis as it affects 98-99% of individuals in this CF patient population. In contrast, acute or persistent respiratory symptoms present in only 51% of total CF patients.

In the subset of males with both CBAVD and URA, the CFTF mutation has been shown to occur at a rate only slightly higher than the overall population. Thus, McCallum, et al. have suggested another mutation may be responsible for this condition.

Treatment
Individuals with CAVD can reproduce with the assistance of modern technology in a procedure known as intracytoplasmic sperm injection. However, as the risk of either cystic fibrosis or renal agenesis is likely to be higher in the children, genetic counseling is generally recommended.