Genetic Evaluation and Counseling for Congenital Bilateral Absence of the Vas Deferens (CBAVD)
Recommended Genetic Testing for Affected Individuals
Limitations of Standard Mutation Panels
Testing of the Female Partner
Renal Imaging Requirement
Ethnicity‑Specific Mutation Frequencies
| Ethnic Group | Frequency of F508del allele* |
|---|---|
| Northern Europe | ~70 % |
| Southern Europe | ~50 % |
| African American | ~48 % |
| U.S. Hispanic | ~46 % |
| Ashkenazi Jewish | ~30 % |
| Native American | Rare |
| Chinese | Rare |
*Data derived from CFTR mutation distribution studies. 2
Genetic Counseling and Phenotypic Expectations
Prevalence and Clinical Characteristics of Congenital Bilateral Absence of the Vas Deferens
Population-Specific Prevalence Data
- CBAVD occurs in approximately 1-2% of all infertile men and accounts for 6% of obstructive azoospermia cases, according to the American Society for Reproductive Medicine 7
- Among men with cystic fibrosis, CBAVD is present in nearly 95% of cases, making it the most sensitive indicator of biallelic CFTR gene abnormalities, as recommended by the Cystic Fibrosis Foundation 8
- In males of northern European heritage, the incidence of clinical CF (which includes CBAVD) is 1:2,000, with an equal frequency of men presenting with isolated CBAVD without significant respiratory or pancreatic disease, as reported by the European Cystic Fibrosis Society 7, 9, 10
Clinical Context and Diagnostic Considerations
- CBAVD presents with characteristic semen findings: low volume ejaculate, acidic pH (<7.0), and azoospermia, which can be diagnosed definitively by physical examination demonstrating bilateral absence of the vasa deferentia, as stated by the American Urological Association 7, 11
- The vast majority of CBAVD patients (78%) carry at least one CFTR mutation, with 46% having two identifiable mutations and 28% having only one mutation detected on standard testing, according to the National Institute of Child Health and Human Development 8
- Between 10-20% of CBAVD cases remain without a genetic diagnosis despite comprehensive CFTR and ADGRG2 testing, and many of these unexplained cases are associated with unilateral renal agenesis, as noted by the American Society of Andrology 12
- CUAVD is associated with ipsilateral renal anomalies in 26-75% of cases, compared to only 10% in bilateral vasal agenesis, making abdominal imaging essential regardless of CFTR status, as recommended by the Society for the Study of Male Reproduction 12