Congenital absence of the vas deferens
|Congenital absence of the vas deferens|
|Classification and external resources|
Congenital absence of the vas deferens (CAVD) is a condition in which the vasa deferentia reproductive organs, fail to form properly prior to birth. It may either be unilateral (CUAVD) or bilateral (CBAVD).
The vas deferens connect the sperm-producing testicles to the penis. Therefore, those 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.
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 CFTR 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.
Scrotal ultrasonography and transrectal ultrasonography (TRUS) are useful in detecting uni- or bilateral CBAVD, which may be associated with visible abnormalities or agenesis of the epididymis, seminal vesicles or kidneys.
Individuals with CAVD can reproduce with the assistance of modern technology with a combination of testicular sperm extraction and intracytoplasmic sperm injection (ICSI). However, as the risk of either cystic fibrosis or renal agenesis is likely to be higher in the children, genetic counseling is generally recommended.
- Online 'Mendelian Inheritance in Man' (OMIM) VAS DEFERENS, CONGENITAL BILATERAL APLASIA OF; CBAVD -277180
- Grangeia A, Sá R, Carvalho F, et al. (2007). "Molecular characterization of the cystic fibrosis transmembrane conductance regulator gene in congenital absence of the vas deferens". Genet. Med. 9 (3): 163–72. doi:10.1097/GIM.0b013e3180318aaf. PMID 17413420.
- McCallum, T.J.; Milunsky, J.M.; Munarriz, R.; Carson, R.; Sadeghi-Nejad, H.; Oates, R.D. "Unilateral renal agenesis associated with congenital bilateral absence of the vas deferens: phenotypic findings and genetic considerations".
- Rosenstein BJ, Cutting GR (1998). "The diagnosis of cystic fibrosis: a consensus statement. Cystic Fibrosis Foundation Consensus Panel". J Pediatr. 132 (4): 589–95. doi:10.1016/S0022-3476(98)70344-0. PMID 9580754.
- Lotti, F.; Maggi, M. (2014). "Ultrasound of the male genital tract in relation to male reproductive health". Human Reproduction Update. 21 (1): 56–83. doi:10.1093/humupd/dmu042. ISSN 1355-4786.