Congenital bilateral absence of the vas deferens and cystic fibrosis. A genetic commonality.

CF and CBAVD are really just ends of a clinical spectrum. The type and nature of the mutations in the CF gene probably determine the phenotypic expression of the patient. Perhaps all patients homozygous for delta F508, for example, will have severe pulmonary and pancreatic disease as well as absent vasa, whereas those with other combinations, such as delta F508/D1270N, will be unaffected in terms of pulmonary and pancreatic function but will have absent vasa. Besides contributing to a better understanding of the nature of CBAVD, this linkage of CF and CBAVD most importantly mandates genetic screening and counseling for appropriate family members and even the patient's spouse. In addition, a broader understanding of CF is now at hand, as this brings a whole new cohort of patients under the CF umbrella. Many of these will have at least one, if not two, rare or novel CF gene mutations. Once all of these mutations have been detected and defined, our knowledge of the CF gene, its mutations, and their implications will be dramatically expanded.