Pathogenic Variants and Genotypes of the CFTR Gene in Russian Men with Cystic Fibrosis and CBAVD Syndrome
by
, , and
Vyacheslav Chernykh
1,2,*,
Stanislav Krasovsky
1,
Olga Solovova
1,
Tagui Adyan
1,
Anna Stepanova
1,
Ekaterina Marnat
2,
Maria Shtaut
1,
Anna Sedova
1,
Tatyana Sorokina
1,
Tatyana Beskorovainaya
1,
Elena Kondratyeva
1,
Olga Shchagina
1
and
Aleksandr Polyakov
1 1
Research Centre for Medical Genetics, 115522 Moscow, Russia
2
Pirogov Russian National Research Medical University of the Ministry of Healthcare of the Russian Federation, 117997 Moscow, Russia
*
Author to whom correspondence should be addressed.
Int. J. Mol. Sci. 2023, 24(22), 16287; https://doi.org/10.3390/ijms242216287
Submission received: 21 October 2023
/
Revised: 9 November 2023
/
Accepted: 11 November 2023
/
Published: 14 November 2023
(This article belongs to the Special Issue Molecular Pathology and Therapy on Cystic Fibrosis and CFTR-Related Diseases)
Abstract
:Pathogenic CFTR variants cause cystic fibrosis (CF), and CF-related disorders (CF-RD), including bilateral aplasia of the vas deferens (CBAVD). The spectrum of clinical manifestations depends on the CFTR genotype. The frequency and spectrum of the CFTR variants vary between populations and clinical groups. CFTR variants and genotypes were analyzed in Russian men with CF (n = 546) and CBAVD syndrome (n = 125). Pathogenic variants were detected in 93.95% and 39.2% of the CF and CBAVD alleles, respectively. The most frequent c.1521_1523del (F508del; p.Phe508del) variant was found in 541 (49.5%) CF alleles. A total of 162 CFTR genotypes were revealed in CF patients, including 152 homozygous and 394 compound-heterozygous. The most common CF-genotype was F508del/F508del (24.9%). Other frequent CF-genotypes were F508del/3849+10kbC>T, F508del/CFTRdele2,3, and F508del/E92K. CF-causing variants and/or 5T allele were found in 88% of CBAVD patients: 5T/CFTRmut (48.0%), CFTRmut/N (17.6%), CFTRmut/CFTRmut (6.4%), 5T/5T (10.4%), 5T/N (5.6%) and N/N (12.0%), with the most common CBAVD-genotype being F508del/5T (29.6%). The allele frequencies of F508del, CFTRdele2,3 394delTT, and 3849+10kbC>T were significantly higher in CF patients. L138ins/L138ins, 2184insA/E92K, and L138ins/N genotypes were found in CBAVD, but not in CF patients. The results indicate certain differences in the frequency of some CFTR variants and genotypes in Russian CF and CBAVD patients.
1. Introduction
Infertility is a common medico-social problem affecting 10–15% of married couples. “Male factor” is revealed in about half of all infertile couples, with genetic abnormalities responsible for at least 50% of cases of severe infertility [1]. Common genetic causes of male infertility include sex chromosome abnormalities (Klinefelter syndrome, X/XY mosaicism, disomy Y, and others), the Y chromosome microdeletions in the AZF (azoospermia factor) locus, and CFTR gene variants [2,3,4].
Pathogenic CFTR (cystic fibrosis transmembrane conduction regulator) gene variants are a cause of cystic fibrosis, CF (OMIM#219700), and CFTR-related disorders (CFTR-RD), particularly, congenital bilateral aplasia of vas deferens (CBAVD) [2,3,4,5]. Cystic fibrosis is a common monogenic autosomal recessive disorder in Caucasian populations. This multisystemic disease results from impaired sodium and chloride transport across epithelial surfaces, and is characterized by progressive obstructive pulmonary disorder, pancreatic, hepatobiliary, and gastrointestinal dysfunction [3,4].
CBAVD syndrome (OMIM# 277180) is an autosomal recessive disease, considered as “genital form” of CF in male patients. In adult male patients, CBAVD is one of the manifestations of Cystic Fibrosis, but it may be independent of CF disease without extragenital symptoms [4]. Some patients with CBAVD syndrome show extragenital symptoms of CF (chronic pancreatitis, bronchitis, sinusitis), which are usually mild and develop mainly in adulthood. Therefore, differential diagnosis and identification of mild (“atypical”) forms of CF and other CFTR-RD in azoospermic patients, especially the heterozygosity for CFTR gene variants, is highly relevant. CBAVD is a common cause of obstructive azoospermia, accounting for 25% of its cases, and is diagnosed in 1–2% of infertile men from various populations [6,7]. However, the actual frequency of congenital bilateral and unilateral aplasia of vas deferens (CBAVD and CUAVD, respectively) is rather underestimated. It is due to a number of problems in differential diagnosis CAVD from other forms of obstructive azoospermia and oligozoospermia [8]. Overall, in 80% patients, CBAVD syndrome is resulted from CF-causing variants/5T allele of the CFTR gene; rare cases of this disorder are caused by pathogenic variants in the ADGRG2 or other candidate genes (SLC9A3, SCNN1B, and CA12) [8].
The CFTR gene is located on chromosome 7 (7q31.2), has a size of about 189 Kb, and consists of 27 exons and 26 introns [9]. CFTR protein is a member of the ATP-binding cassette (ABC) transporter superfamily, which functions as a chloride channel, controlling ion and water secretion and absorption in epithelial tissues [9]. To date, more than 2,000 pathogenic variants in the CFTR gene have been identified [9]. The severity and spectrum of clinical manifestations depend on the severity of the CFTR genotype, which determines the degree of defect/preservation of the encoded protein.
Numerous studies show that the genotypes of patients with CF and CBAVD syndrome differ significantly, with the combination of two “severe” pathogenic variants in trans-position, i.e., on both CFTR alleles, leads to severe forms of CF [10]. Commonly, CBAVD syndrome is characterized by genotypes with “mild” CFTR mutations in combination with the 5T allele (IVS-9T5 polymorphic variant), which is detected in 40–50% of CBAVD patients and in 4–5% individuals of Caucasian origin [11,12]. The frequency of CBAVD syndrome varies in different regions (in European populations, it is slightly higher than in Asian populations), which is probably due to the different frequencies of pathogenic CFTR gene variants in different regions and ethnic groups [10,11].
The frequency and spectrum of the CFTR gene variants significantly vary between different populations, ethnic and clinical groups, particularly CF and CF-RD. The spectrum of the CFTR gene variants and genotypes in Russian CF patients has been studied in detail, including differences in various age groups (children and adults), as well as in different regions of the Russian Federation [13]. However, to date, no combined study of Russian CF patients and men with CBAVD syndrome has been performed. Therefore, the aim of the present study was a comparative analysis of common pathogenic CFTR gene variants and genotypes in Russian men with cystic fibrosis and Russian patients with CBAVD syndrome.
2. Results
CF-causing variants were detected in 1124 (83.76%) of 1342 analyzed CFTR alleles, including all of 546 (100%) CF patients and 90 (72%) men with CBAVD syndrome. In CF patients, pathogenic CF-causing CFTR gene variants were found in 1026 (93.95%) of the 1092 analyzed alleles. As many as 91 different CFTR gene variants were revealed in CF patients. Sixteen different CF-causing variants (F508del, CFTRdele2,3, 3849+10kbC>T, E92K, 2184insA, 2143delT, L138ins, N1303K, G542X, W1282X, 1677delTA, R334W, 604insA, G85E, 4015delA, 3272-26A>G) were detected in both CF patients and CBAVD patients (Table 1).
In the CF patients’ group, 162 CFTR genotypes were detected. CF patients were found to be homozygous (n = 152) or compound-heterozygous (n = 394). The most frequent was the F508del/F508del genotype revealed in 136 (24.9%) CF patients (Table 2).
The second most common genotype was compound heterozygous F508del/unknown, detected in 45 (8.2%) CF patients and 45 (36.0%) CBAVD patients. Other three common CF-causing genotypes (F508del/3849+10kbC>T, F508del/CFTRdele2,3 and F508del/E92K) F508del/3849+10kbC>T, F508del/CFTRdele2,3 and F508del/E92K were found in 38 (7.0%), 33 (6.0%), and 23 (4.2%) CF patients, respectively.
In CBAVD patients, pathogenic CF-causing variants were detected in 98 (39.2%) of CFTR alleles. 16 different variants were revealed in this group (Table 1). Eight individuals with CBAVD syndrome were found to have two CF-causing variants, including two compound-heterozygous (n = 7) and one homozygous (L138ins/L138ins) (Table 3).
In CBAVD patients, the F508del variant was revealed in 45 (18%) of 250 alleles, in 36% of individuals. In this group, besides F508del mutations, more frequent CFTR gene variants were L138ins, CFTRdele2,3(21Kb), W1282X, which consisted of 8.2%, 7.1%, and 6.1% of all detected CF-causing variants, respectively. Overall, pathogenic CFTR gene variants and/or 5T allele were found in 110 (88.0%) of the 125 examined CBAVD patients (Figure 1).
Analysis of the IVS9-Tn polymorphic locus in intron 9 of the CFTR gene detected three allelic variants: 5T, 7T, and 9T. The 5T (IVS9-5T) allele was found in 93 (37.2%) of 250 alleles, in 80 of 125 (64%) patients with CBAVD syndrome (Table 3). This allelic variant of the CFTR gene was detected in the homozygous state (n = 13; 10.4% of patients) and in the heterozygous state (n = 67; 53.6% of patients) in combination with 7T or 9T alleles. Totally, CFTR gene mutation and/or 5T were found in 110 (88.0%) of 125 CBAVD patients (Table 3). Following CFTR genotypes were revealed in CBAVD patients: 5T/mut (n = 60; 48.0%), mut/N (n = 20; 17.6%), mut/mut (n = 8; 6.4%), 5T/5T (n = 13; 10.4%), 5T/N (n = 7; 5.6%), and N/N (n = 15; 12.0%), at that the most common was the F508del/5T genotype detected in 45 (36.0%) individuals in this group (Figure 1).
The allelic frequency of some CFTR variants dramatically differs between the patient groups due to the high prevalence of homozygosity and compound-heterozygosity in CF patients. So, the c.1521_1523delCTT (p.(Phe508del), F508del)) variant was a more common variant in both CF (44.4%) and CBAVD (20.4%) patients, but the allelic frequency (AF) was significantly higher in the former group (0.49542 and 0.2, respectively; χ2 = 70.853; p < 0.001). Also, three other variants (CFTRdele2,3, 3849+10kbC-T, and 394delTT) have shown statistically significant higher (p < 0.003) allele frequencies in CF patients than in men with CBAVD syndrome (Table 1). The 5T allele was found accidentally in one patient who developed pancreas-sufficient CF (PS-CF) with R117C(c.349C>T)/IVS9-TG12-T5 genotype.
Some CFTR genotypes showed a statistically significant (p < 0.05) difference between CF and CBAVD patients. So, the prevalence of the F508del/N genotype was significantly higher in CBAVD individuals than in CF patients (36.0% vs. 8.24%; χ2 = 65.084; p < 0.001). F508del/F508del, F508del/3849+10kbC>T, F508del/CFTRdele2,3 and F508del/E92K genotypes were found only in CF patients (Table 2). L138ins/L138ins, 2184insA/E92K, and L138ins/N genotypes were found in men with CBAVD syndrome, but not in CF patients (Table 2 and Table 3).
3. Discussion
The results of the present study indicate a high prevalence of CFTR gene mutations in Russian men with CBAVD syndrome. A comparative analysis of the prevalence of various CFTR pathogenic variants in the two evaluated groups indicates a similar distribution of their occurrence among both adult men with CF and CBAVD syndrome from the Russian Federation. According to our recent research, ten following CF-causing variants, F508del, CFTRdele2,3, L138ins, W1282X, 1677delTA, 3849+10kbC>T, E92K, 2143delT, G542X, and 2184insA, are more common in Russian infertile men [14]. Their allelic frequency (AF) is 0.0005 or more, and the proportion of each variant is 2% or more of all detected pathogenic CFTR gene variants in both Russian infertile men and CBAVD patients.
F508del (c.1521_1523delCTT; p.Phe508del) variant is the most common CFTR gene mutation both in Russian men with cystic fibrosis and patients with CBAVD syndrome (44.4% and 52.0% of all detected mutations in these groups, respectively). Previously, we examined CFTR genotypes in a sample of 72 Russian patients with CBAVD [15]. The data of the evaluation of CFTR variants and genotypes in a larger sample of CBAVD patients are consistent with data on a smaller sample of patients.
All examined CF patients are characterized by the presence of one or two pathogenic CFTR gene variants, either in a homozygous or in compound heterozygous state. While in the sample of CBAVD patients, two mutations are rare (<5%), CBAVD is characterized by “mild” CFTR genotypes [11]. Severe CF-causing variants in the homozygous state were not detected among the examined CBAVD patients. Out of 125 patients, only 8 patients had two CF-causing variants (Table 3). One individual was found to have a mutation in the homozygous state (L138ins/L138ins), and 7 patients were compound-heterozygous for the combination of “severe” (F508del) variants and one of the “mild” CFTR gene variants, or two “mild” CFTR gene variants. It should be noted that at least some of them may have or develop “atypical” cystic fibrosis with age.
According to the literature, men from European populations with “isolated CBAVD”, CBAVD without diagnosed cystic fibrosis, homozygotes for “severe” pathogenic CF-causing variants were also not revealed, but compound heterozygotes for a “severe” mutation with the R117H (c. 350G>A) variant of the CFTR gene are often found in patients with CBAVD from Western European populations [10,11,16]. The R117H variant is a “mild” mutation, the allelic frequency of which in men with CBAVD averages 3%, of which 4.0–11.3% in Caucasian patients, while the F508del/R117H genotype is found in 4–6% of patients. This variant of the CFTR gene is not typical for other populations [10,11], including Russian CF patients [17]. Thus, we did not detect any R117H variant among patients from both samples.
Interestingly, 394delTT is one of the common CFTR gene variants detected in 17 (3.1%) Russian CF patients (including in homozygous, n = 4, and heterozygous, n = 13), but not in Russian men with CBAVD syndrome. This variant is the second (4%) of the most frequent “Nordic” CFTR mutations in CF patients from Danish, Swedish, Norwegian, and Finnish populations [18]. In West-European populations, this variant has also been reported in a few patients with CBAVD/CUAVD syndromes [8]. According to the RUSeq database [http://ruseq.ru/ accessed on 20 September 2023], in the European part of Russia, the allelic frequency (AF) of the 394delTT (rs121908769) variant is 0.0002134. This variant is the second most common CFTR gene variant (3.5% of all detected mutations) in CF patients from Bashkortostan [19]. In participants (n = 642) from the population-based cohort study ESSE-Vologda, the 394delTT (rs121908769) variant was found to have 0.0047 alleles [20]. This variant of the CFTR gene was found in a large cohort of 6,033 Russian infertile men [14]. However, a heterozygous 394delTT variant was detected in 2 of the 2,146 Russian infertile men examined by Solovyova et al. (2018) [21]. Both of these patients had a 394delTT/N, 7T/9T genotype; one of them was normozoospermic; the spermatological diagnosis of the second patient was not provided; and the presence of CBAVD was not indicated.
Overall, the CFTR gene mutation and/or 5T allele was found in 88% of Russian infertile men with CBAVD syndrome. This is consistent with our results and data from other researchers, who found that 80–85% of CBAVD patients of Caucasian origin have CF-causing variants and/or 5T allele of the CFTR gene [3]. In the spectrum of CFTR genotypes, CFTRmut/5T was the most common in our cohort (29.6%) and in other samples of CBAVD patients, especially in a large cohort of patients from France (28.44%) [3]. The second most common CFTR genotype in our cohort of Russian men with CBAVD syndrome was 5T/5T homozygosity, revealed in 10.4% of patients. Recently, we reported the results of an analysis of the CFTR gene on a smaller sample of Russian CBAVD patients (n = 72) and they were generally similar to the data on a larger sample [15].
Two CF-causing mutations in the CFTR genotype were found in 8 (6.4%) patients, while the L138ins variant was revealed in 7 out of 16 alleles, and the proportion of this mutation was 7.1% of all detected mutations. Thus, L138ins was found to be the second most common CFTR gene variant in Russian patients with CBAVD syndrome, and the third in prevalence after F508del and CFTRdele2.3(kb) in Russian infertile men. The allele frequency (AF) of this variant in Russian infertile men (n = 6033) was 0.0014 [14]. The L138ins variant was found as compound heterozygous F508del/L138ins in four CBAVD patients (Table 3). This genotype was also found in 3 CF patients. Notable, that these CBAVD patients did not have “classic” forms of CF, but at least some had adult-onset pancreatitis or respiratory disease. The possibility of undiagnosed CF or CFTR-RD should be taken into account in the examination of infertile men, especially in patients with obstructive azoospermia.
It should be noted that our study is not without drawbacks. Not all patients underwent sequencing and analysis of major rearrangements or copy number variants, CNVs (for example, deletions and duplications) in the CFTR gene. A comprehensive analysis of the nucleotide variants could identify up to 99% of pathogenic alleles. So, Petrova et al. (2018) identified up to 99% and found 10 (9.6%) intergenic CNVs of 104 Russian CF patients. Taulan et al. have identified pathogenic CFTR variants (two variants—82.4% and one variant—9.3%) in 91.7% of CBAVD patients from European populations. Subsequently, they have detected two large heterozygous complex deletions (one encompassing exon 2, the other removing exons 22–24) in the CFTR gene in two CBAVD patients, and both individuals had pathogenic variants on the other allele [22]. Ma et al. detected 5 CNVs (4 partial deletions and 1 partial duplication) in the CFTR gene in 1.9% (5/263) Chinese CBAVD patients [23]. Although their frequency would be low, we cannot exclude rare nucleotide variants or intergenic in some CF and CBAVD patients from our sample, which had CFTR alleles considered “normal” or unknown CF-causing variants. Screening for large genomic rearrangements in the CFTR gene is beneficial not only in CF but also in CBAVD patients, especially for those azoospermic men who are carriers of a CFTR “mild” mutation/5T allele.
The R117H variant is one of the most common non-CF-causing CFTR gene variants in European populations and is frequently detected in patients with CBAVD syndrome. This missense variant (p.(Arg117His)) is generally considered to be a mild CFTR gene mutation (class IV). In the samples of men with CF and CBAVD syndrome in the present study, the R117H variant was not investigated. According to the RUSeq database [http://ruseq.ru/accessed on 20 September 2023], allelic frequency (AF) of the R117H (rs78655421, NM_000492.4: c.350G>A) variant is 0.0012 in the general population from European part of Russia; in Caucasian and Eastern parts of Russia, the AF of this variant is 0.0000, possibly due to the small number of individuals studied. Solovyova et al. (2018) analyzed the CFTR gene in 2146 Russian men from infertile couples, and detected the R117H variant in 8 patients, including four compound-heterozygous F508del/R117H; 9T/7T (azoospermia, n = 4); and four heterozygous R117H/N; 7T/7T (azoospermia, n = 3; oligozoospermia, n = 1) [24]. CBAVD syndrome was diagnosed in 3 patients with the F508del/R117H genotype; the ethnicity of the individuals was not specified. It should be noted that the sample of patients examined by Solovyova et al. consisted of individuals from Western Siberia (Krasnoyarsk). In a cohort of 2146 Russian infertile men examined by Solovieva et al., CBAVD was diagnosed in 10 patients with the following CFTR genotypes: F508del/R117H, 9T/7T (n = 3), F508del/L138ins, 9T/7T (n = 1); F508del/N, 9T/5T-12TG (n = 1); CFTRdele2,3(21kb)/N, 7T/5T-12TG (n = 1), F508del/N, 9T/7T (n = 2), and N/N, 7T/7T (n = 2) [24]. No other studies have been performed in Russian patients with CBAVD syndrome.
Modern methods of assisted reproductive technologies (ART), especially the IVF/ICSI procedure, allow having children in patients with various forms of male infertility, including obstructive azoospermia due to CF/CBAVD [25]. The high frequency of the CFTR gene variants in patients with CBAVD/obstructive azoospermia should be taken into account; therefore, their children are at increased risk for both CF and CF-RD patients. In this regard, genetic counseling and screening for pathogenic CFTR gene variants are very important for these patients and their spouses. Couples at high risk should be offered preimplantation genetic testing (PGT) or prenatal DNA diagnosis.
4. Materials and Methods
A cohort of examined individuals consisted of 671 unrelated Russian men, including 125 patients with CBAVD syndrome and 546 adult male CF patients. The patients with CBAVD syndrome had no diagnosed cystic fibrosis. All CF patients had one or two pathogenic CFTR gene variants. Informed consent for the study was obtained from all participants.
Molecular study was performed on genomic DNA extracted from peripheral blood leukocytes using the QIAamp DNA Blood Mini Kit (Qiagen, Valencia, CA, USA).
The CFTR gene was analyzed for 22 following common in Russian populations pathogenic variants (CFTRdele2,3(21kb), 394delTT, 3944delTG, L138ins, R334W, F508del, I507del, 1677delTA, G542X, 2143delT, 2184insA, 3821delT, 3849+10kb C>T, 604insA, 621+1G>T, E92K, S1196X, W1282X, N1303K, 4022insT, 4015delA, and 3272-26A>G). These variants were detected using amplified fragment length polymorphism (APLF-PCR) and multiplex ligation-dependent probe amplification (MLPA) methods. In CBAVD patients, the IVS9-Tn polymorphic locus was analyzed by two-round (nested) PCR. The results of PCR amplification and the allele-specific ligase reaction were evaluated by electrophoresis on an 8% polyacrylamide gel. The methods were previously described in detail [14,15]. Some variants were detected using additional molecular analysis of the CFTR gene using MLPA, DNA sequencing by the Sanger method, or massive parallel sequencing (MPS).
A classification of the genotypes into “severe” or “moderate” is based on the severity of the negative effect of different pathogenic CFTR variants on the function of the encoded protein in accordance with the generally accepted classification [3].
Statistical analysis was performed using the STATISTICA software, version 13.0 (StatSoft Inc., Tulsa, OK, USA). A significant difference in the frequencies of the CFTR gene alleles and genotypes was evaluated using the χ2 criterion. Results were considered reliable if the level of the index did not exceed 0.05 (p < 0.05).
5. Conclusions
Russian adult male patients with cystic fibrosis and CBAVD syndrome share a similar spectrum of pathogenic CFTR gene variants; however, some of the variants and genotypes dramatically differ between these patients’ groups. So, the “mild” CF-causing 3849+10kbC>T variant characterized for PS-CF is common in adult men with cystic fibrosis, including some azoospermic CF patients having CBAVD, but this variant is extremely rare in isolated congenital bilateral aplasia of the vas deferens. 394delTT is one of the common CF-causing variants in Russian CF patients, but not in CBAVD patients. In contrast, some other CFTR gene variants (L138ins, 2143delT, and W1282X) were detected 3–4 times more common in CBAVD, than in CF patients. Total frequency of CF-causing variants and 5T allele, as well as the structure of CFTR genotypes in Russian men with CBAVD syndrome, is very similar to the patients from European populations.
Author Contributions
Conceptualization, V.C.; methodology, V.C., A.P. and O.S. (Olga Shchagina); investigation, T.A., T.B., A.S. (Anna Stepanova) and M.S.; resources, S.K., T.S., T.A. and E.K.; data curation, V.C., S.K., E.M. and A.S. (Anna Sedova); writing—original draft preparation, V.C. and O.S. (Olga Solovova); visualization, A.S. (Anna Stepanova); supervision, V.C.; project administration, V.C. and A.P. All authors have read and agreed to the published version of the manuscript.
Funding
The present study was performed within the framework of the project Multicenter Research Bio-resource Collection “Human Reproductive Health” No. 15.BRK.21.0008 of the Ministry of Science and Higher Education of the Russian Federation.
Institutional Review Board Statement
The study was conducted in accordance with the Declaration of Helsinki, and approved by the Institutional Review Board (or Ethics Committee) of Research Centre for Medical Genetics (protocol code: №4/3; date of approval: 19 April 2021).
Informed Consent Statement
Informed consent was obtained from all subjects involved in the study.
Data Availability Statement
Data are contained within the article.
Conflicts of Interest
The authors declare no conflict of interest.
References
- Vander Borght, M.; Wyns, C. Fertility and Infertility: Definition and Epidemiology. Clin. Biochem. 2018, 62, 2–10. [Google Scholar] [CrossRef] [PubMed]
- Chillón, M.; Casals, T.; Mercier, B.; Bassas, L.; Lissens, W.; Silber, S.; Romey, M.-C.; Ruiz-Romero, J.; Verlingue, C.; Claustres, M.; et al. Mutations in the Cystic Fibrosis Gene in Patients with Congenital Absence of the Vas Deferens. N. Engl. J. Med. 1995, 332, 1475–1480. [Google Scholar] [CrossRef] [PubMed]
- Claustres, M. Molecular Pathology of the CFTR Locus in Male Infertility. Reprod. Biomed. Online 2005, 10, 14–41. [Google Scholar] [CrossRef]
- Bombieri, C.; Claustres, M.; De Boeck, K.; Derichs, N.; Dodge, J.; Girodon, E.; Sermet, I.; Schwarz, M.; Tzetis, M.; Wilschanski, M.; et al. Recommendations for the Classification of Diseases as CFTR-Related Disorders. J. Cyst. Fibros. 2011, 10, S86–S102. [Google Scholar] [CrossRef] [PubMed]
- Bieth, E.; Hamdi, S.M.; Mieusset, R. Genetics of the Congenital Absence of the Vas Deferens. Hum. Genet. 2021, 140, 59–76. [Google Scholar] [CrossRef] [PubMed]
- Cai, Z.; Li, H. Congenital Bilateral Absence of the Vas Deferens. Front. Genet. 2022, 13, 775123. [Google Scholar] [CrossRef]
- Hussein, T.M.; Zakaria, N.H.; Zahran, A.M. Clinical Laboratory and Genetic Assessment of Patients with Congenital Bilateral Absent Vas Deferens. Andrologia 2011, 43, 16–22. [Google Scholar] [CrossRef]
- Fedder, J.; Jørgensen, M.W.; Engvad, B. Prevalence of CBAVD in Azoospermic Men Carrying Pathogenic CFTR Mutations-Evaluated in a Cohort of 639 Non-vasectomized Azoospermic Men. Andrology 2021, 9, 588–598. [Google Scholar] [CrossRef]
- Bareil, C.; Bergougnoux, A. CFTR Gene Variants, Epidemiology and Molecular Pathology. Arch. Pédiatr. 2020, 27, eS8–eS12. [Google Scholar] [CrossRef]
- Yu, J.; Chen, Z.; Ni, Y.; Li, Z. CFTR Mutations in Men with Congenital Bilateral Absence of the Vas Deferens (CBAVD): A Systemic Review and Meta-Analysis. Hum. Reprod. 2012, 27, 25–35. [Google Scholar] [CrossRef]
- Casals, T.; Bassas, L.; Egozcue, S.; Ramos, M.D.; Giménez, J.; Segura, A.; Garcia, F.; Carrera, M.; Larriba, S.; Sarquella, J.; et al. Heterogeneity for Mutations in the CFTR Gene and Clinical Correlations in Patients with Congenital Absence of the Vas Deferens. Hum. Reprod. 2000, 15, 1476–1483. [Google Scholar] [CrossRef] [PubMed]
- Petrova, N.; Balinova, N.; Marakhonov, A.; Vasilyeva, T.; Kashirskaya, N.; Galkina, V.; Ginter, E.; Kutsev, S.; Zinchenko, R. Ethnic Differences in the Frequency of CFTR Gene Mutations in Populations of the European and North Caucasian Part of the Russian Federation. Front. Genet. 2021, 12, 678374. [Google Scholar] [CrossRef] [PubMed]
- Petrova, N.V.; Kashirskaya, N.Y.; Vasilyeva, T.A.; Kondratyeva, E.I.; Zhekaite, E.K.; Voronkova, A.Y.; Sherman, V.D.; Galkina, V.A.; Ginter, E.K.; Kutsev, S.I.; et al. Analysis of CFTR Mutation Spectrum in Ethnic Russian Cystic Fibrosis Patients. Genes 2020, 11, 554. [Google Scholar] [CrossRef]
- Chernykh, V.; Sorokina, T.; Sedova, A.; Shtaut, M.; Solovova, O.; Marnat, E.; Adyan, T.; Beskorovaynaya, T.; Stepanova, A.; Shchagina, O.; et al. L138ins Variant of the CFTR Gene in Russian Infertile Men. Genes 2023, 14, 1407. [Google Scholar] [CrossRef] [PubMed]
- Marnat, E.G.; Adyan, T.A.; Stepanova, A.A.; Beskorovainaya, T.S.; Polyakov, A.V.; Chernykh, V.B. CFTR Gene Variants and Genotypes in Russian Patients with CBAVD Syndrome. Russ. J. Genet. 2020, 56, 496–501. [Google Scholar] [CrossRef]
- Thauvin-Robinet, C.; Munck, A.; Huet, F.; de Becdelièvre, A.; Jimenez, C.; Lalau, G.; Gautier, E.; Rollet, J.; Flori, J.; Nové-Josserand, R.; et al. CFTR p.Arg117His Associated with CBAVD and Other CFTR-Related Disorders. J. Med. Genet. 2013, 50, 220–227. [Google Scholar] [CrossRef]
- Cui, X.; Wu, X.; Li, Q.; Jing, X. Mutations of the Cystic Fibrosis Transmembrane Conductance Regulator Gene in Males with Congenital Bilateral Absence of the Vas Deferens: Reproductive Implications and Genetic Counseling (Review). Mol. Med. Rep. 2020, 22, 3587. [Google Scholar] [CrossRef]
- Schwartz, M.; Anvret, M.; Claustres, M.; Eiken, H.; Eiklid, K.; Schaedel, C.; Stolpe, L.; Tranebjaerg, L. 394delTT: A Nordic Cystic Fibrosis Mutation. Hum. Genet. 1994, 93, 157–161. [Google Scholar] [CrossRef]
- Korytina, G.F.; Viktorova, T.V.; Ivashchenko, T.E.; Baranov, V.S.; Khusnutdinova, E.K. The Mutation Spectrum of the CFTR Gene in Cystic Fibrosis Patients from Bashkortostan. Mol. Biol. 2003, 37, 56–61. [Google Scholar] [CrossRef]
- Kiseleva, A.; Klimushina, M.; Sotnikova, E.; Skirko, O.; Divashuk, M.; Kurilova, O.; Ershova, A.; Khlebus, E.; Zharikova, A.; Efimova, I.; et al. Cystic Fibrosis Polymorphic Variants in a Russian Population. Pharmgenom. Pers. Med. 2020, 13, 679–686. [Google Scholar] [CrossRef]
- de Souza, D.A.S.; Faucz, F.R.; Pereira-Ferrari, L.; Sotomaior, V.S.; Raskin, S. Congenital Bilateral Absence of the Vas Deferens as an Atypical Form of Cystic Fibrosis: Reproductive Implications and Genetic Counseling. Andrology 2018, 6, 127–135. [Google Scholar] [CrossRef] [PubMed]
- Taulan, M.; Girardet, A.; Guittard, C.; Altieri, J.-P.; Templin, C.; Beroud, C.; des Georges, M.; Claustres, M. Large Genomic Rearrangements in the CFTR Gene Contribute to CBAVD. BMC Med. Genet. 2007, 8, 22. [Google Scholar] [CrossRef] [PubMed]
- Ma, C.; Wang, R.; Li, T.; Li, H.; Wang, B. Analysis of CNVs of CFTR Gene in Chinese Han Population with CBAVD. Mol. Genet. Genom. Med. 2020, 8, e1506. [Google Scholar] [CrossRef] [PubMed]
- Solovyova, E.V.; Tataru, D.A.; Preda, O.G.; Artyukhova, V.G.; Sekira, A.G.; Derevjeva, V.Y.; Makhalova, N.A.; Novoseltseva, A.V.; Rendashkin, I.V.; Zaitseva, T.A.; et al. CFTR Mutations in Male Infertility. Med. Genet. 2018, 17, 28–38. [Google Scholar] [CrossRef]
- Petrova, N.V.; Marakhonov, A.V.; Vasilyeva, T.A.; Kashirskaya, N.Y.; Ginter, E.K.; Kutsev, S.I.; Zinchenko, R.A. Comprehensive Genotyping Reveals Novel CFTR Variants in Cystic Fibrosis Patients from the Russian Federation. Clin. Genet. 2019, 95, 444–447. [Google Scholar] [CrossRef]
Figure 1.
CFTR genotypes in Russian patients with CBAVD syndrome (n = 125).
Table 1.
CF-causing CFTR gene variants in Russian men with CF and CBAVD syndrome.
| Pathogenic CFTR Gene Variant | CF, n = 546 | CBAVD, n = 125 | ||
|---|---|---|---|---|
| Alleles, n (AF) | Percentage of Detected Variants, % | Alleles, n (AF) | Percentage of Detected Variants, % | |
| c.1521_1523delCTT (p.Phe508del, F508del) | 541 (0.49542) 1 | 52.7 | 50 (0.200) 1 | 51.0 |
| c.54-5940_273+10250del21kb (p.(Ser18Argfs*16), CFTRdele2,3) | 72 (0.65934) 2 | 7.0 | 7 (0.028) 2 | 7.1 |
| c.3718-2477C>T (3849+10kbC-T) | 55 (0.05037) 3 | 5.4 | 1 (0.004) 3 | 1.0 |
| c.274G>A (p.Glu92Lys, E92K) | 42 (0.03846) | 4.1 | 4 (0.016) | 4.1 |
| c.2052_2053insA (p.Gln685ThrfsX4, 2184insA) | 29 (0.02656) | 2.8 | 4 (0.016) | 4.1 |
| c.2012delT (p.Leu671X, 2143delT) | 23 (0.02106) | 2.2 | 5 (0.020) | 5.1 |
| c.262_263delTT (p.Leu88IlefsX22, 394delTT) | 21 (0.01923) 4 | 2.0 | - 4 | 0.0 |
| c.413_415dupTAC (p.Leu138dup; L138ins) | 20 (0.01832) | 1.9 | 8 (0.032) | 8.2 |
| c.3909C>G (p.Asn1303Lys, N1303K) | 20 (0.01832) | 1.9 | 3 (0.012) | 3.1 |
| c.1624G>T (p.Gly542X, G542X) | 17 (0.01557) | 1.7 | 3 (0.012) | 3.1 |
| c.3846G>A (p.Trp1282X, W1282X) | 16 (0.01465) | 1.6 | 6 (0.024) | 6.1 |
| c.1545_1546delTA (p.Tyr515X, 1677delTA) | 12 (0.01099) | 1.2 | 2 (0.008) | 2.0 |
| c.1000C>T (p.Arg334Trp, R334W) | 9 (0.00824) | 0.9 | 1 (0.004) | 1.0 |
| c.1397C>G (p.Ser466X, Ser466X) | 8 (0.00733) | 0.8 | - | 0.0 |
| c.3844T>C (p.Trp1282Arg, W1282R) | 8 (0.00733) | 0.8 | - | 0.0 |
| c.3140-16T>A (3272-16T>A) | 8 (0.00733) | 0.8 | - | 0.0 |
| c.2657+5G>A (2789+5A>G) | 6 (0.00549) | 0.6 | - | 0.0 |
| c.3691delT (p.Ser1231ProfsX4, 3821delT) | 6 (0.00549) | 0.6 | - | 0.0 |
| c.1243_1247del (p.Asn415X, 1367del5) | 6 (0.00549) | 0.6 | - | 0.0 |
| c.3196C>T (p.Arg1066Cys, R1066C) | 4 (0.00366) | 0.4 | - | 0.0 |
| c.3587C>G (p.Ser1196X, S1196X) | 4 (0.00366) | 0.4 | - | 0.0 |
| c.3816_3817delGT (p.Ser1273LeufsX28, 3944delGT) | 3 (0.00274) | 0.3 | - | 0.0 |
| c.489+1G>T (621+1G>T) | 3 (0.00274) | 0.3 | - | 0.0 |
| c.1766+1G>A (1898+1G>A) | 3 (0.00274) | 0.3 | - | 0.0 |
| c.1766+1G>A (1898+1G>C) | 3 (0.00274) | 0.3 | - | 0.0 |
| c.1040G>C (p.Arg347Pro, R347P) | 3 (0.00274) | 0.3 | - | 0.0 |
| c.3484C>T (p.Arg1162X, R1162X) | 3 (0.00274) | 0.3 | - | 0.0 |
| c.3476C>T (p.Ser1159Phe, S1159F) | 3 (0.00274) | 0.3 | - | 0.0 |
| c.442del (p.Ile148LeufsX5, 574delA) | 2 (0.00183) | 0.2 | - | 0.0 |
| c.472dupA (p.Ser158LysfsX5, 604insA) | 2 (0.00183) | 0.2 | 1 (0.004) | 1.0 |
| c.254G>A (p.Gly85Glu, G85E) | 2 (0.00183) | 0.2 | 1 (0.004) | 1.0 |
| c.3883delA; (p.Ile1295Phefs, 4015delA) | 1 (0.00092) | 0.1 | 1 (0.004) | 1.0 |
| c.3890_3891insT (p.Gly1298Trpfs, 4022insT) | 1 (0.00092) | 0.1 | - | 0.0 |
| c.3140-26A>G (3272-26A>G) | 1 (0.00092) | 0.1 | 1 (0.004) | 1.0 |
| Others 5 | 69 | 6.7 | - | 0.0 |
1—the allelic frequency (AF) is significantly higher in CF patients (χ2 = 70.853; p < 0.001). 2—AF is significantly higher in CF patients (χ2 = 5.284; p = 0.022). 3—AF is significantly higher in CF patients (χ2 = 10.937; p < 0.001). 4—AF is significantly higher in CF patients (χ2 = 4.884; p = 0.028). 5—Other CF-causing variants: R553X, S945L, S1159P, 3849G>A,4382delA, Y569H, 175delC, 3659delC, 3849G>A, 574delA, and A141D (n = 22); 185+1G>T, 461A>G, 712-1G>T, 1248+1G>A, 1525-1G>A, 1716+1G->A, 2114delT, 2183AA>G, 2721del11, 2790-2A>G, 3667ins4, 4015delA, 4022insT, S945L, 624delT, 663delT, A96E, c.174_177delTAGA, c.1761del, c.3325delA, c.3893delG, c.4078delG, CFTRdele4-11(4-10*), CFTRdele19-21, D572N, G314R, G480S, L1335P, p.Asp993Ala, p.Glu402X, p.Glu1433Gly, p.Leu581X, p.Lys1468Asn, p.Pro988Arg, p.Tyr84X, Q98R, Q493R, R117C, R668C, R785X, R1158X, R1531I, T604I, W401X, W1310X, Y1032C, and IVS9-TG12T5 (n = 47).
Table 2.
CFTR genotypes in Russian men with cystic fibrosis (n = 546).
| CFTR Genotypes | Severity | Number, n | Percentage of Detected CFTR Genotypes, % |
|---|---|---|---|
| F508del/F508del | Severe | 136 | 24.9 |
| F508del/unknown | n.a. | 45 | 8.2 |
| F508del/3849+10kbC->T | Moderate | 38 | 7.0 |
| F508del/CFTRdele2,3 | Severe | 33 | 6.0 |
| F508del/E92K | Moderate | 23 | 4.2 |
| F508del/2143delT | Severe | 12 | 2.2 |
| F508del/2184insA | Severe | 12 | 2.2 |
| F508del/L138ins | Moderate | 9 | 1.6 |
| F508del/G542X | Severe | 8 | 1.5 |
| F508del/W1282X | Severe | 7 | 1.3 |
| F508del/2789+5G>A | Moderate | 5 | 0.9 |
| F508del/N1303K | Severe | 5 | 0.9 |
| F508del/394delTT | Severe | 4 | 0.7 |
| F508del/3272-16T>A | Moderate | 4 | 0.7 |
| F508del/3821delT | Severe | 4 | 0.7 |
| CFTRdele2,3/2184insA | Severe | 4 | 0.7 |
| CFTRdele2,3/G542X | Severe | 4 | 0.7 |
| CFTRdele2,3/N1303K | Severe | 4 | 0.7 |
| E92K/E92K | Moderate | 4 | 0.7 |
| 394delTT/394delTT | Severe | 4 | 0.7 |
| 394delTT/unknown | n.a. | 4 | 0.7 |
| 3849+10kbC>T/unknown | Moderate | 3 | 0.5 |
| CFTRdele2,3/L138ins | Moderate | 3 | 0.5 |
| E92K/N1303K | Moderate | 3 | 0.5 |
| F508del/1367del5 | Severe | 3 | 0.5 |
| F508del/R334W | Moderate | 3 | 0.5 |
| F508del/R1066C | Severe | 3 | 0.5 |
| F508del/S1196X | Severe | 3 | 0.5 |
| F508del/1677delTA | Severe | 2 | 0.4 |
| F508del/3849G>A | Moderate | 2 | 0.4 |
| F508del/4382delA | Moderate | 2 | 0.4 |
| F508del/604insA | Severe | 2 | 0.4 |
| F508del/621+1G>T | Moderate | 2 | 0.4 |
| F508del/R1162X | Severe | 2 | 0.4 |
| F508del/W1282R | Moderate | 2 | 0.4 |
| F508del/Y569H | Moderate | 2 | 0.4 |
| F508del/1898+1G>A | Severe | 2 | 0.4 |
| CFTRdele2,3/CFTRdele2,3 | Severe | 2 | 0.4 |
| CFTRdele2,3/1367del5 | Severe | 2 | 0.4 |
| CFTRdele2,3/E92K | Moderate | 2 | 0.4 |
| CFTRdele2,3/R334W | Moderate | 2 | 0.4 |
| CFTRdele2,3/unknown | n.a. | 2 | 0.4 |
| 3849+10kbC>T/S466X(TGA)/R1070Q | Moderate | 2 | 0.4 |
| 2184insA/G542X | Severe | 2 | 0.4 |
| 2184insA/L138ins | Moderate | 2 | 0.4 |
| 2143delT/N1303K | Severe | 2 | 0.4 |
| 2143delT/unknown | n.a. | 2 | 0.4 |
| 1677delTA/1677delTA | Severe | 2 | 0.4 |
| 394delTT/3272-16T>A | Moderate | 2 | 0.4 |
| W1282X/S466X(TGA)/R1070Q | Unknown | 2 | 0.4 |
| Others | - | 112 | 20.5 |
n.a.—not assessed.
Table 3.
CFTR genotypes in 125 Russian patients with CBAVD syndrome.
| CFTR Genotypes | Number of Patients, N (Percentage of All Patients, %) | |
|---|---|---|
| CF-Causing Variants | IVS-9Tn | |
| F508del/L138ins | 9T/7T | 4 (3.2%) |
| F508del/N1303K | 9T/7T | 1 (0.8%) |
| L138ins/N1303K | 7T/9T | 1 (0.8%) |
| L138ins/L138ins | 7T/7T | 1 (0.8%) |
| 2184insA/E92K | 7T/7T | 1 (0.8%) |
| F508del/N | 9T/5T | 37 (29.6%) |
| 7T/9T | 8 (6.4%) | |
| L138ins/N | 7T/5T | 1 (0.8%) |
| CFTRdele2,3(21Kb)/N | 7T/7T | 2 (1.6%) |
| 7T/5T | 5 (4.0%) | |
| W1282X/N | 7T/5T | 5 (4.0%) |
| 7T7T | 1 (0.8%) | |
| 2143delT/N | 9T/5T | 1 (0.8%) |
| 7T/5T | 1 (0.8%) | |
| 9T/9T | 1 (0.8%) | |
| 7T/9T | 2 (1.6%) | |
| 2184insA/N | 7T/5T | 2 (1.6%) |
| 7T/7T | 1 (0.8%) | |
| E92K/N | 7T/5T | 1 (0.8%) |
| 7T/7T | 1 (0.8%) | |
| 7T/9T | 1 (0.8%) | |
| G542X/N | 9T/5T | 2 (1.6%) |
| 7T/5T | 1 (0.8%) | |
| N1303K/N | 9T/5T | 1 (0.8%) |
| 1677delTA/N | 7T/7T | 1 (0.8%) |
| 7T/5T | 1 (0.8%) | |
| 604insA/N | 7T/5T | 1 (0.8%) |
| 3849+10KbC-T/N | 7T/7T | 1 (0.8%) |
| R334W/N | 7T/7T | 1 (0.8%) |
| 4015delA/N | 7T/7T | 1 (0.8%) |
| 3272-26A>G/N | 7T/5T | 1 (0.8%) |
| G85E/N | 7T/5T | 1 (0.8%) |
| N/N | 9T/5T | 2 (1.6%) |
| 5T/7T | 5 (4.0%) | |
| 5T/5T | 13 (10.4%) | |
| 7T/7T | 11 (8.8%) | |
| 7T/9T | 4 (3.2%) | |
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content. |
© 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
Share and Cite
MDPI and ACS Style
Chernykh, V.; Krasovsky, S.; Solovova, O.; Adyan, T.; Stepanova, A.; Marnat, E.; Shtaut, M.; Sedova, A.; Sorokina, T.; Beskorovainaya, T.; et al. Pathogenic Variants and Genotypes of the CFTR Gene in Russian Men with Cystic Fibrosis and CBAVD Syndrome. Int. J. Mol. Sci. 2023, 24, 16287. https://doi.org/10.3390/ijms242216287
AMA Style
Chernykh V, Krasovsky S, Solovova O, Adyan T, Stepanova A, Marnat E, Shtaut M, Sedova A, Sorokina T, Beskorovainaya T, et al. Pathogenic Variants and Genotypes of the CFTR Gene in Russian Men with Cystic Fibrosis and CBAVD Syndrome. International Journal of Molecular Sciences. 2023; 24(22):16287. https://doi.org/10.3390/ijms242216287
Chicago/Turabian StyleChernykh, Vyacheslav, Stanislav Krasovsky, Olga Solovova, Tagui Adyan, Anna Stepanova, Ekaterina Marnat, Maria Shtaut, Anna Sedova, Tatyana Sorokina, Tatyana Beskorovainaya, and et al. 2023. "Pathogenic Variants and Genotypes of the CFTR Gene in Russian Men with Cystic Fibrosis and CBAVD Syndrome" International Journal of Molecular Sciences 24, no. 22: 16287. https://doi.org/10.3390/ijms242216287
Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.
