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 AF508, for example, will have severe pulmonary and pancreatic disease as well as absent vasa, whereas those with other combinations, such as AF508/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.
Congenital bilateral absence of the vas deferens (CBAVD) occurs in approximately 1.4Β°70 of the infertile male population . The disorder is characterized by the bilateral absence of scrotal vasa. A strict definition of CBAVD needs to be adhered to and physical examination of the scrotal vasa remains the best way to make the diagnosis. If either one or both vasa are palpable from their origin at the lower pole of the epididymis all the way to their disappearance at the external ring, then CBAVD is n o t present. CBAVD, by definition, occurs only when both scrotal vasa are deficient, either partially or totally. This distinction is important and necessary at this point in time for the proper categorization of the various types of vasal agenesis and the subsequent study of the genetic ab-