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A male factor, commonly associated with poor semen quality, is revealed in about 50% of infertile couples. CFTR gene (Cystic Fibrosis Transmembrane Conduction Regulator) variants are one of the common genetic causes of azoospermia-related male infertility. Notably, the spectrum and frequency of pathogenic CFTR variants vary between populations and geographical regions. In this work, we made an attempt to evaluate the allele frequency (AF) of 12 common CFTR variants in infertile Russian men and healthy individuals from different districts of Russia. Because of the limited number of population-based studies on Russian individuals, we characterized the population AFs based on data from the Registry of Russian cystic fibrosis (CF) patients. In addition to the CF patient registry, we estimated the local frequencies of the same set of variants based on the results of genotyping of CF patients in local biocollections (from St. Petersburg and Yugra regions). AFs of common CFTR variants calculated based on registry and biocollection data showed good concordance with directly measured population AFs. The estimated region-specific frequencies of CFTR variants allowed us to uncover statistically significant regional differences in the frequencies of the F508del (c.1521_1523del; p.Phe508del) and CFTRdele2,3(21kb) (c.54-5940_273+10250del21kb; p.Ser18ArgfsX) variants. The data from population-based studies confirmed previous observations that F508del, CFTRdele2,3(21kb), and L138ins (c.413_415dup; p.Leu138dup)variants are the most abundant among infertile patients, and their frequencies are significantly lower in healthy individuals and should be taken into account during genetic monitoring of the reproductive health of Russian individuals. [ABSTRACT FROM AUTHOR]

We examined a cohort of 93 cystic fibrosis (CF) male patients who were pancreatic-sufficient (PS-CF; n=40) or pancreatic-insufficient (PI-CF; n = 53). Complex semen examination was performed, including standard semen analysis, quantitative karyological analysis (QKA) of immature germ cells (IGCs), transmission electronic microscopy (TEM), biochemical analysis, and sperm DNA fragmentation by terminal deoxynucleotidyl transferase-mediated dUTP nickend labeling (TUNEL) assay. Azoospermia was diagnosed in 83 (89.2%) patients. The other 10 (10.8%) patients were found to be nonazoospermic and showed various spermatological diagnoses (asthenozoospermia, n = 2; asthenoteratozoospermia, n = 3; oligoasthenozoospermia, n = 1; oligoasthenoteratozoospermia, n = 3; and normozoospermia, n = 1) with no specific morphological abnormalities. Oligospermia was detected in 89.2% azoospermic and 30.0% nonazoospermic patients. Low seminal pH (<7.0) was found in 74 (89.2%) of 83 azoospermic patients. Moderate leukocytospermia (2.0 × 106-2.2 × 106 ml-1) was revealed in 2.4% azoospermic and 40.0% nonazoospermic semen samples. The signs of partial meiotic arrest at prophase I were found in 4 of 6 nonazoospermic patients examined by QKA of IGCs. The content of fructose and citrate was low in oligospermic and normal in nonoligospermic semen samples. An increased percentage (>30%) of spermatozoa with noncondensed ("immature") chromatin was revealed in 2 of 6 nonazoospermic semen samples analyzed by TEM. [ABSTRACT FROM AUTHOR]