One hundred randomly selected couples with severe reproductive disorders were examined for the 18 most frequent CFTR mutations reported in 86.1 % Czech cystic fibrosis patients. Only mutation DF508 was disclosed. Our results indicate an increased frequency of this mutation in examined males (8 %), whereas DF508 in females is not increased (1%). The frequency of allele „5T“ of intron 8 polymorphism in males and females does not differ significantly (8%, 6%) and corresponds to the European carrier - frequency. A statistically increased frequency of mutation DF508 was revealed in males affected with azoospermia or severe oligospermia with sperm counts less than 1 x 10 6 /ml without the presence of CAVD only. An increased frequency of mutation DF508 in examined males having a sperm count higher than 1 x 10 6 /ml was not found. The detection of CFTR mutations is recommended not only in males with CAVD but also in males with non-obstructive azoospermia or severe oligospermia with sperm counts less than 1 x 10 6 /ml. The disclosure of the CFTR mutation in male indicates molecular genetic examination of his female partner, in order to prevent cystic fibrosis in their child in case of successful assisted reproduction. The results of our study support the hypothesis, that the CFTR gene is involved the development of the vas deferens and in the process of spermatogenesis as well in.

        Key words: CFTR mutation gene, severe reproductive disorders, azoospermia, oligospermia