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It has been proposed that the gene responsible for cystic fibrosis, called the cystic fibrosis transmembrane conductance regulator (CFTR) gene, may play an important role in the process of spermatogenesis. A group of azoospermic men with primary testicular failure underwent CFTR mutation analysis, including assessment of the intron 8 polythymidine tract (IVS8-T tract). An association was not found between CFTR mutations or the 5T variant of the IVS8-T tract and the primary testicular failure phenotype. This finding suggests that CFTR does not play a significant role in the aetiopathogenesis of primary spermatogenic dysfunction. Therefore, the abnormal testicular histological findings in some post-pubertal men with cystic fibrosis may be a result of nutritional deficiency or testicular obstruction rather than a primary defect in spermatogenesis. In addition, the decreased sperm count in oligozoospermic men with CFTR mutations may be secondary to partial reproductive tract obstruction and not abnormal spermatogenesis. Lastly, routine screening of men with primary testicular failure for CFTR gene mutations is not warranted.

Context: Infertile men with obstructive azoospermia may have mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, many of which are rare in classic cystic fibrosis and not evaluated in most routine mutation screening., Objective: To assess how often CFTR mutations or sequence alterations undetected by routine screening are detected with more extensive screening in obstructive azoospermia., Design: Routine screening for the 31 most common CFTR mutations associated with the CF phenotype in white populations, testing for the 5-thymidine variant of the polythymidine tract of intron 8 (IVS8-5T) by allele-specific oligonucleotide hybridization, and screening of all exons through multiplex heteroduplex shift analysis followed by direct DNA sequencing., Setting: Male infertility clinic of a Canadian university-affiliated hospital., Subjects: Of 198 men with obstructive (n = 149) or nonobstructive (n = 49; control group) azoospermia, 64 had congenital bilateral absence of the vas deferens (CBAVD), 10 had congenital unilateral absence of the vas deferens (CUAVD), and 75 had epididymal obstruction (56/75 were idiopathic)., Main Outcome Measure: Frequency of mutations found by routine and nonroutine tests in men with obstructive vs nonobstructive azoospermia., Results: Frequency of mutations and the IVS8-5T variant in the nonobstructive azoospermia group (controls) (2% and 5.1% allele frequency, respectively) did not differ significantly from that in the general population (2% and 5.2%, respectively). In the CBAVD group, 72 mutations were found by DNA sequencing and IVS8-5T testing (47 and 25, respectively; P<.001 and P = .002 vs controls) vs 39 by the routine panel (P<.001 vs controls). In the idiopathic epididymal obstruction group, 24 mutations were found by DNA sequencing and IVS8-5T testing (12 each; P=.01 and P=.14 vs controls) vs 5 by the routine panel (P=.33 vs controls). In the CUAVD group, 2 mutations were found by routine testing (P=.07 vs controls) vs 4 (2 each, respectively; P=.07 and P=.40 vs controls) by DNA sequencing and IVS8-5T testing. The routine panel did not identify 33 (46%) of 72, 2 (50%) of 4, and 19 (79%) of 24 detectable CFTR mutations and IVS8-5T in the CBAVD, CUAVD, and idiopathic epididymal obstruction groups, respectively., Conclusions: Routine testing for CFTR mutations may miss mild or rare gene alterations. The barrier to conception for men with obstructive infertility has been overcome by assisted reproductive technologies, thus raising the concern of iatrogenically transmitting pathogenic CFTR mutations to the progeny.