Congenital bilateral absence of the vas deferens

More than half of all men with CBAVD have mutations in the _CFTR _gene. Mutations in this gene also cause cystic fibrosis. When CBAVD occurs with _CFTR _mutations, it is considered a form of atypical cystic fibrosis. In instances of CBAVD without a mutation in the _CFTR _gene, the cause of this condition 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 pattern of inheritance means that both copies of the gene in each cell have a mutation. Parents of a person with CBAVD each carry one CFTR mutation, but are usually unaffected (carriers). Men with CBAVD who choose to father children through assisted reproduction have an increased risk of having a child with cystic fibrosis. If congenital absence of the vas deferens is not caused by mutations in CFTR , the risk of having children with cystic fibrosis is not increased.

The risk to siblings of a person with CBAVD depends on the affected person's CFTR gene mutation(s) and cannot readily be predicted without this information. Genetic testing is most informative when the CBAVD-causing mutations have been identified in the affected individual. Men with CBAVD sometimes have only one identifiable CFTR mutation, complicating the testing and interpretation of results in their family members. We recommend speaking with a genetics professional about risk to other family members as well as any appropriate genetic testing.