CYSTIC-FIBROSIS AND INFERTILITY CAUSED BY CONGENITAL BILATERAL ABSENCE OF THE VAS-DEFERENS AND RELATED CLINICAL ENTITIES

The condition of congenital bilateral absence of the vas deferens (CBA VD) is, in the majority of patients, related to defects in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. CBAVD patien ts either are compound heterozygotes (carrying different mutations in their two CFTR genes) or carry a mutation in one of their CFTR genes a nd an intron 8 5T splice variant, associated with low levels of functi onal CFTR protein, in their second gene. The relationship between cyst ic fibrosis (CF) and CBAVD requires a proper clinical examination of t he patient, a CFTR mutation analysis for himself and his family and ge netic counselling. A mutation analysis should also be performed for th e wives of CBAVD males because such couples now have the possibility o f having their own genetic children but are at increased risk of havin g children with CF and/or CBAVD. The aetiology of some conditions of C BAVD is not related to CF, especially when CBAVD is associated with ur inary tract malformations (up to 20% of cases). In couples with CBAVD not related to CF there is no increased risk of CF children, but it is not known whether they have an increased risk of having sons with CBA VD. In some of the patients with congenital unilateral absence of the vas deferens (CUAVD) the condition is also related to CF, especially i n cases where there is an occlusion of the palpable vas. The CFTR gene is probably not involved in the aetiology of Young's syndrome. Follow -up studies of children born to couples where the males have CBAVD, CU AVD or Young's syndrome are mandatory and will help to better define t he risk to their offspring of CF and/or of inheriting their paternal i nfertility condition.