CYSTIC-FIBROSIS MUTATION SCREENING IN CBAVD PATIENTS AND MEN WITH OBSTRUCTIVE AZOOSPERMIA OR SEVERE OLIGOZOOSPERMIA

Congenital bilateral absence of the vas deferens (CBAVD) found in othe rwise healthy infertile males, is associated with a high incidence of mutated cystic fibrosis transmembrane conductance regulator (CFTR) all eles, and is considered a genital form of cystic fibrosis (CF). The CF gene may also be involved in the aetiology of male infertility in cas es other than CBAVD. The present study was undertaken to test the invo lvment of CFTR gene mutations in 14 CBAVD males and additionally in ca ses of male infertility caused by obstructive azoospermia (n = 10) and severe oligozoospermia (n = 3). The entire coding region of the CFTR gene was analysed using denaturing gradient gel electrophoresis (DGGE) . The three allele (5T, 7T, 9T) polymorphic tract of thymidines in int ron 8 (IVS8-polyT) of which the 5T allele acts as a mild mutation, cau sing reduced levels of normal CFTR mRNA due to deletion of exon 9, was also analysed. Of the 14 CBAVD cases, four (28.6%) were found to have mutations in both copies of the CFTR gene, six (42.8%) had one CFTR m utation, and in the remaining four (28.6%) no CFTR mutations were foun d. Of the 10 cases with obstructive azoospermia, three (30%) had one C FTR mutation and in the remaining seven (70%) no mutations were found. None of the three severe oligozoospermia cases carried a CFTR mutatio n. The frequency of the IVS8(5T) allele was 14.3% (4/28) for the CBAVD cases and 5% (1/20) for the obstructive azoospermia cases, none of th e severe oligozoospermia males carried the IVS8-5(5T) allele. The data indicate that while there is a strong association between male infert ility caused by CBAVD and mutations in the CFTR gene, cases of obstruc tive azoospermia without CBAVD also seem to be associated with CFTR ge ne mutations.