Congenital bilateral absence of vas deferens

Congenital bilateral absence of vas deferens occurs in men when the tubes that carry sperm from the testes (the vas deferens) fail to develop normally. This condition can occur alone or as a sign of cystic fibrosis (an inherited disease of the mucus glands).

Men with congenital bilateral absence of vas deferens are infertile (unable to conceive a child). The testes usually develop and function normally and the men have normal sexual performance, but sperm cannot be transported through the male reproductive system.

When this condition occurs in the absence of typical cystic fibrosis, most men have no other health problems. Some men with the disorder have mild respiratory or digestive symptoms, however.

This condition is responsible for 2 to 5 percent of all infertility in men.

Mutations in the CFTR gene cause congenital bilateral absence of vas deferens.

More than half of all men with this condition have identified mutations in the CFTR gene. Mutations in this gene also cause cystic fibrosis. When congenital bilateral absence of vas deferens occurs with CFTR mutations, it is considered to be a form of atypical cystic fibrosis.

The protein made by the CFTR gene forms a channel that controls the movement of salt and water into and out of cells. Mutations in the CFTR gene alter this protein in such a way that the channel is blocked, disrupting the movement of salt and water. As a result, cells produce thick mucus that blocks the developing vas deferens.

When there is no mutation in the CFTR gene, the cause of this disorder is often unknown. Some cases are associated with other structural problems of the urinary tract.

When this condition is caused by mutations in the CFTR gene, it is inherited in an autosomal recessive pattern. This means that both copies of the gene must be altered for a person to be affected by the disorder. Men with congenital absence of vas deferens caused by CFTR mutations are at an increased risk of having a child with cystic fibrosis. If congenital absence of vas deferens is not caused by mutations in CFTR, there is no increased risk of having children with cystic fibrosis.

You may find the following resources about congenital bilateral absence of vas deferens helpful.

• MedlinePlus - Health Information (2 links)
• Educational resources - Information pages
  Orphanet
• Patient support - For patients and families
  Resolve: The National Infertility Association

You may also be interested in these resources, which are designed for healthcare professionals and researchers.

• Gene Reviews - Clinical summary
• Gene Tests - DNA tests ordered by healthcare professionals
• PubMed - Recent literature
• OMIM - Genetic disorder catalog

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atypical ; autosomal ; autosomal recessive ; channel ; congenital ; digestive ; gene ; infertile ; infertility ; mutation ; protein ; recessive ; respiratory ; sign ; symptom ; testes ; vas deferens

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.