CFTR mutations in men with congenital bilateral absence of the vas deferens (CBAVD): a systemic review and meta-analysis

The interactome of cystic fibrosis transmembrane conductance regulator and its role in male fertility: A critical review

The cystic fibrosis transmembrane conductance regulator (CFTR) is a cyclic adenosine monophosphate (cAMP)-regulated chloride and bicarbonate ion channel found in many human cells. Its unique biochemical characteristics and role as a member of the adenosine triphosphate (ATP)-binding cassette transporters superfamily are pivotal for the transport of several substrates across cellular membranes. CFTR is known to interact, physically and functionally, with several other cellular proteins. Hence, its properties are essential for moving various substances across cell membranes and ensuring correct cell functioning. Genetic mutations or environmental factors may disrupt CFTR's function resulting in different possible phenotypes due to gene variations that affect not only CFTR's function, localization, and processing within cells, but also those of its interactors. This has been reported as an underlying cause of various diseases, including cystic fibrosis. The severe clinical implications of cystic fibrosis have driven intense research into the role of CFTR in lung function but its significance to fertility, particularly in men, has been comparatively understudied. However, ongoing and more recent research into CFTR and its interacting proteins in the testis or specific testicular cells is beginning to shed light on this field. Herein, we provide a comprehensive and up-to-date overview of the CFTR, its interactome, and its crucial role in male reproduction, highlighting recent discoveries and advancements in understanding the molecular mechanisms involved. The comprehension of these complex interactions may pave the way for potential therapeutic approaches to improve fertility of men suffering from alterations in the function of CFTR.

Etiology of Male Infertility: an Update

Spermatogenesis is a complex process of germ cell division and differentiation that involves extensive cross-talk between the developing germ cells and the somatic testicular cells. Defective endocrine signaling and/or intrinsic defects within the testes can adversely affect spermatogenic progression, leading to subfertility/infertility. In recent years, male infertility has been recognized as a global public health concern, and research over the last few decades has elucidated the complex etiology of male infertility. Congenital reproductive abnormalities, genetic mutations, and endocrine/metabolic dysfunction have been demonstrated to be involved in infertility/subfertility in males. Furthermore, acquired factors like exposure to environmental toxicants and lifestyle-related disorders such as illicit use of psychoactive drugs have been shown to adversely affect spermatogenesis. Despite the large body of available scientific literature on the etiology of male infertility, a substantial proportion of infertility cases are idiopathic in nature, with no known cause. The inability to treat such idiopathic cases stems from poor knowledge about the complex regulation of spermatogenesis. Emerging scientific evidence indicates that defective functioning of testicular Sertoli cells (Sc) may be an underlying cause of infertility/subfertility in males. Sc plays an indispensable role in regulating spermatogenesis, and impaired functional maturation of Sc has been shown to affect fertility in animal models as well as humans, suggesting abnormal Sc as a potential underlying cause of reproductive insufficiency/failure in such cases of unexplained infertility. This review summarizes the major causes of infertility/subfertility in males, with an emphasis on infertility due to dysregulated Sc function.

An overview of CFTR mutation profiles and assisted reproductive technology outcomes in Chinese patients with congenital obstructive azoospermia

PURPOSE

The cystic fibrosis transmembrane conductance regulator (CFTR) is the most common causative gene attributed to congenital obstructive azoospermia (OA). The aim of this study was to conduct an epidemiological survey of congenital OA patients, to screen for CFTR mutations, and to follow their pregnancy outcomes in assisted reproductive technology (ART).

METHODS

This cohort study enrolled congenital OA patients undergoing ART and whole-exome sequencing from January 2018 to September 2023. Semen parameters, sex hormones, and seminal plasma biochemistry were evaluated. CFTR mutations identified in OA patients were analyzed. In addition, the laboratory outcomes, clinical outcomes, and neonatal outcomes were compared between OA patients carrying two CFTR mutations and the others after surgical sperm extraction-intracytoplasmic sperm injection (ICSI) treatment.

RESULTS

A total of 76 patients with congenital OA were enrolled. CFTR mutations were identified in 35 (46.1%) congenital OA patients. A total of 60 CFTR mutation sites of 27 types were identified, and 10 of them were novel. The average frequency was 1.71 (60/35) per person. The most common mutation was c.1210-11T > G (25%, 15/60). After ICSI treatment, there were no statistically significant differences in laboratory outcomes, clinical outcomes, and neonatal outcomes between OA patients carrying two CFTR mutations (n = 25) and other OA patients (n = 51).

CONCLUSION

Apart from the IVS9-5T mutation, the genetic mutation pattern of CFTR in Chinese OA patients is heterogeneous, which is significantly different from that of Caucasians. Although carrying two CFTR mutations or not had no effect on the pregnancy outcomes in OA patients after ICSI, genetic counseling is still recommended for such patients.

Male Factor Infertility: What Every OB/GYN Should Know

Male factor infertility plays a role in approximately 30% of infertility cases. Various causes of male factor infertility exist including congenital, acquired, idiopathic, or environmental factors. Identifying the underlying etiology of male factor infertility is a key step toward providing appropriate counseling, effective treatment options, and improving outcomes for couples with infertility. Although the recent advances and developments in assisted reproductive technology have undoubtedly improved fertility outcomes, clinicians must understand the scope of reproductive urologists in the evaluation and treatment of male infertility to provide comprehensive counseling, appropriate referral, comprehensive evaluation, and correct surgical sperm retrieval techniques when needed.

Multi-omics study identifies that PICK1 deficiency causes male infertility by inhibiting vesicle trafficking in Sertoli cells

BACKGROUND

Infertility affects approximately 10-15% of reproductive-age men worldwide, and genetic causes play a role in one-third of cases. As a Bin-Amphiphysin-Rvs (BAR) domain protein, protein interacting with C-kinase 1 (PICK1) deficiency could lead to impairment of acrosome maturation. However, its effects on auxiliary germ cells such as Sertoli cells are unknown.

PURPOSE

The present work was aimed to use multi-omics analysis to research the effects of PICK1 deficiency on Sertoli cells and to identify effective biomarkers to distinguish fertile males from infertile males caused by PICK1 deficiency.

METHODS

Whole-exome sequencing (WES) was performed on 20 infertility patients with oligozoospermia to identify pathogenic PICK1 mutations. Multi-omics analysis of a PICK1 knockout (KO) mouse model was utilized to identify pathogenic mechanism. Animal and cell function experiments of Sertoli cell-specific PICK1 KO mouse were performed to verify the functional impairment of Sertoli cells.

RESULTS

Two loss-of-function deletion mutations c.358delA and c.364delA in PICK1 resulting in transcription loss of BAR functional domain were identified in infertility patients with a specific decrease in serum inhibin B, indicating functional impairment of Sertoli cells. Multi-omics analysis of PICK1 KO mouse illustrated that targeted genes of differentially expressed microRNAs and mRNAs are significantly enriched in the negative regulatory role in the vesicle trafficking pathway, while metabolomics analysis showed that the metabolism of amino acids, lipids, cofactors, vitamins, and endocrine factors changed. The phenotype of PICK1 KO mouse showed a reduction in testis volume, a decreased number of mature spermatozoa and impaired secretory function of Sertoli cells. In vitro experiments confirmed that the expression of growth factors secreted by Sertoli cells in PICK1 conditional KO mouse such as Bone morphogenetic protein 4 (BMP4) and Fibroblast growth factor 2 (FGF2) were decreased.

CONCLUSIONS

Our study attributed male infertility caused by PICK1 deficiency to impaired vesicle-related secretory function of Sertoli cells and identified a variety of significant candidate biomarkers for male infertility induced by PICK1 deficiency.

Pathogenic Variants and Genotypes of the CFTR Gene in Russian Men with Cystic Fibrosis and CBAVD Syndrome

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.

Compound heterozygous variants in CFTR with potentially reducing ATP-binding ability identified in Chinese infertile brothers with isolated congenital bilateral absence of vas deferens

BACKGROUND

Isolated congenital bilateral absence of vas deferens (iCBAVD) in men results in obstructive azoospermia and is mainly caused by pathogenic variants in cystic fibrosis transmembrane conductance regulator (CFTR) or adhesion G protein-coupled receptor G2 (ADGRG2).

METHODS

The next-generation sequencing (NGS) was used to screen the mutations in the proband, and Sanger sequencings were performed to validate the compound heterozygous variant of CFTR in his family members. Protein structure simulation was performed to discover the potential pathological mechanism.

RESULTS

This study reported novel compound heterozygous CFTR mutations (NM:000492.4, Intron: 5T; c.3965_3969dupTTGGG: p.R1325Gfs*5) in two brothers with obstructive azoospermia. The compound heterozygous CFTR mutations were first screened out by NGS in an infertile male patient who exhibited iCBAVD from a nonconsanguineous Chinese family. Histological analysis of the testicular biopsy from this patient revealed normal spermatogenesis and mature spermatozoa were observed in the seminiferous tubules. Surprisingly, the same compound heterozygous CFTR mutations were also observed in his brothers who also exhibited iCBAVD, with their parents being a heterozygous carrier for the mutations, as verified by Sanger sequencing. Protein structure simulation revealed that these mutations potentially led to impaired ATP-binding ability of CFTR.

CONCLUSION

We identified novel compound heterozygous CFTR mutations in two brothers and summarized the literature regarding CFTR mutation and male infertility. Our study may contribute to the genetic diagnosis of iCBAVD and future genetic counseling.

A Comprehensive Genetic Study of Microtubule-Associated Gene Clusters for Male Infertility in a Taiwanese Cohort

Advanced reproductive technologies are utilized to identify the genetic mutations that lead to spermatogenic impairment, and allow informed genetic counseling to patients to prevent the transmission of genetic defects to offspring. The purpose of this study was to identify potential single nucleotide polymorphisms (SNPs) associated with male infertility. Genetic variants that may cause infertility are identified by combining the targeted next-generation sequencing (NGS) panel and whole exome sequencing (WES). The validation step of Sanger sequencing adds confidence to the identified variants. Our analysis revealed five distinct affected genes covering seven SNPs based on the targeted NGS panel and WES data: SPATA16 (rs16846616, 1515442, 1515441), CFTR (rs213950), KIF6 (rs2273063), STPG2 (r2903150), and DRC7 (rs3809611). Infertile men have a higher mutation rate than fertile men, especially those with azoospermia. These findings strongly support the hypothesis that the dysfunction of microtubule-related and spermatogenesis-specific genes contributes to idiopathic male infertility. The SPATA16, CFTR, KIF6, STPG2, and DRC7 mutations are associated with male infertility, specifically azoospermia, and a further examination of this genetic function is required.

Male infertility

Clinical infertility is the inability of a couple to conceive after 12 months of trying. Male factors are estimated to contribute to 30-50% of cases of infertility. Infertility or reduced fertility can result from testicular dysfunction, endocrinopathies, lifestyle factors (such as tobacco and obesity), congenital anatomical factors, gonadotoxic exposures and ageing, among others. The evaluation of male infertility includes detailed history taking, focused physical examination and selective laboratory testing, including semen analysis. Treatments include lifestyle optimization, empirical or targeted medical therapy as well as surgical therapies that lead to measurable improvement in fertility. Although male infertility is recognized as a disease with effects on quality of life for both members of the infertile couple, fewer data exist on specific quantification and impact compared with other health-related conditions.

Sexual and Reproductive Health Among Men With Cystic Fibrosis

Cystic fibrosis (CF) is a genetic disease caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) protein. Due to the distribution of the CFTR protein, CF presents with a heterogeneous phenotype. Men with CF may present with infertility due to congenital abnormalities of the vas deferens. In addition, they may experience testosterone deficiency. Today, they can father biological children with assisted reproductive technologies. We reviewed the current literature on the pathophysiology of these conditions, describe interventions that allow men with CF to conceive biological children, and provide recommendations for management of CF patients with reproductive health concerns.

A novel ADGRG2 truncating variant associated with X-linked obstructive azoospermia in a large Chinese pedigree

PURPOSE

In this study, we aimed to identify sterility-related variants in a Chinese pedigree with male infertility and to reveal the different phenotypes and intracytoplasmic sperm injection (ICSI) outcomes of the affected members.

METHODS

Physical examinations were performed on male patients. G-band karyotype analysis, copy number variation sequencing, and quantitative fluorescent PCR were conducted to detect common chromosomal disorders in the probands. Whole-exome sequencing and Sanger sequencing were applied to identify the pathogenic genes and the protein expression changes caused by the very mutation were identified by Western Blot in vitro.

RESULTS

A novel nonsense mutation (c.908C > G: p.S303*) in the ADGRG2 was identified in all infertile male patients of the pedigree, which was inherited from their mothers. This variant was absent from the human genome databases. This mutation was also unexpectedly found in a male member with normal reproductive capability. Members with the mutation had different genitalia phenotypes, ranging from normal to dilated phenotypes of the vas deferens, spermatic veins and epididymis. There was a truncated ADGRG2 protein in vitro after mutation. Of the three patients' wives treated with ICSI, only one successfully gave birth.

CONCLUSIONS

Our study is the first to report the c.908C > G: p.S303* mutation in the ADGRG2 in an X-linked azoospermia pedigree and is the first to report normal fertility in a member with this mutation, expanding the mutation spectrum and phenotype spectrum of this gene. In our study, ISCI had a success rate of only one-third in couples including men with azoospermia with this mutation.

Correlation between CFTR variants and outcomes of ART in patients with CAVD in Central China

Biallelic variants in Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) are the main pathogenic factor of congenital absence of the vas deferens (CAVD), including congenital bilateral absence of the vas deferens (CBAVD) and congenital unilateral absence of the vas deferens (CUAVD). However, there are few reports about the correlation between CFTR variant and outcomes of assisted reproductive technology (ART) in CAVD patients of China. In this study, 104 patients with CAVD were recruited in Central China, and provided gene detection by the whole-exome sequencing, among them 69% (72/104) carried at least one variant in CFTR and one carried adhesion G protein-coupled receptor G2 (ADGRG2) variant. A total of 81 CAVD patients were treated with ART, of which 21 and 60 carried none or at least one variant in CFTR, respectively. The fertilization rate, cleavage rate, effective embryo rate, implantation rate, clinical pregnancy rate and live birth rate per fresh embryo transfer were compared between patients with and without CFTR variants. It was found that the ART outcomes had no significant difference whether the patients carried the CFTR variant or not. In addition, all of the offspring were healthy after follow-up. In conclusion, rare CFTR variants may play a major role in patients with CAVD in Central China, which were greatly different from other descent. There was no significant difference in ART outcomes in CAVD patients with or without CFTR variants. The limitations of this study were that there was no statistical analysis of the sperm quality through TESA and conclusions were relatively limited due to the small sample size of the study.

Congenital absence of the vas deferens with hypospadias or without hypospadias: Phenotypic findings and genetic considerations

Congenital absence of the vas deferens (CAVD) is a major cause of obstructive azoospermia. Mutations of CFTR and ADGRG2 cause the majority of CAVD. Despite this, 10%–20% of CAVD patients remain without a clear genetic diagnosis. Herein, the CFTR and ADGRG2 genes were first sequenced using Sanger sequencing in 50 CAVD patients. Whole-exome sequencing (WES) was used to further identify potential novel genetic causes in CAVD with hypospadias. In total, 29 of 50 CAVD patients carried at least one CFTR mutation, but no ADGRG2 mutation was found. 5T was found to be the most frequent variant in our CAVD populations. Seven CAVD patients with hypospadias were further analyzed using WES. No homozygous or compound heterozygous mutations related to disorders of sex development (DSDs) or male infertility were identified by WES. CAVD with hypospadias presented lower testicular volume (9.71 ± 2.14 ml vs. 14.45 ± 2.93 ml, p < 0.001) and higher FSH level (FSH: 7.28 ± 3.91 IU/L vs. 4.24 ± 1.96 IU/L, p = 0.027) than CAVD without hypospadias. It is worth noting that neither CFTR or ADGRG2 mutation nor homozygous or compound heterozygous gene mutations were identified in seven CAVD cases with hypospadias. However, nine heterozygous or hemizygous mutations were selected as potential pathogenic genes in CAVD with hypospadias. In conclusion, CFTR variants, especially 5T, play a major role in the Chinese CAVD population. CAVD with hypospadias shows relatively lower testicular spermatogenesis, suggesting a different genetic basis or pathogenic factor from cystic fibrosis/CAVD or unilateral renal agenesis/CAVD.

Ultrasound of the Normal and Abnormal Vas Deferens

ABSTRACT

The extrapelvic portion of the vas deferens is readily visible with ultrasound but often overlooked. Several publications have described the scanning technique and the normal anatomy of the vas deferens. Sonographic evaluation of the vas deferens provides critical information in the workup of male infertility. Obstruction, inflammatory conditions, and neoplasms of the vas deferens can also be diagnosed with ultrasound. Knowledge of the normal and abnormal appearance of the vas deferens improves scans of the scrotum and expands the conditions that can be recognized and accurately diagnosed with ultrasound.

A spectrum of recessiveness among Mendelian disease variants in UK Biobank

Recent work has found increasing evidence of mitigated, incompletely penetrant phenotypes in heterozygous carriers of recessive Mendelian disease variants. We leveraged whole-exome imputation within the full UK Biobank cohort (n ∼ 500K) to extend such analyses to 3,475 rare variants curated from ClinVar and OMIM. Testing these variants for association with 58 quantitative traits yielded 102 significant associations involving variants previously implicated in 34 different diseases. Notable examples included a POR missense variant implicated in Antley-Bixler syndrome that associated with a 1.76 (SE 0.27) cm increase in height and an ABCA3 missense variant implicated in interstitial lung disease that associated with reduced FEV1/FVC ratio. Association analyses with 1,134 disease traits yielded five additional variant-disease associations. We also observed contrasting levels of recessiveness between two more-common, classical Mendelian diseases. Carriers of cystic fibrosis variants exhibited increased risk of several mitigated disease phenotypes, whereas carriers of spinal muscular atrophy alleles showed no evidence of altered phenotypes. Incomplete penetrance of cystic fibrosis carrier phenotypes did not appear to be mediated by common allelic variation on the functional haplotype. Our results show that many disease-associated recessive variants can produce mitigated phenotypes in heterozygous carriers and motivate further work exploring penetrance mechanisms.

Advanced molecular approaches in male infertility diagnosis

In the recent years a special attention has been given to a major health concern namely to male infertility, defined as the inability to conceive after 12 months of regular unprotected sexual intercourse, taken into account the statistics that highlight that sperm counts have dropped by 50-60% in recent decades. According to the WHO, infertility affects approximately 9% of couples globally, and the male factor is believed to be present in roughly 50% of cases, with exclusive responsibility in 30%. The aim of this manuscript is to present an evidence-based approach for diagnosing male infertility that includes finding new solutions for diagnosis and critical outcomes, retrieving up-to-date studies and existing guidelines. The diverse factors that induce male infertility generated in a vast amount of data that needed to be analysed by a clinician before a decision could be made for each individual. Modern medicine faces numerous obstacles as a result of the massive amount of data generated by the molecular biology discipline. To address complex clinical problems, vast data must be collected, analysed, and used, which can be very challenging. The use of artificial intelligence (AI) methods to create a decision support system can help predict the diagnosis and guide treatment for infertile men, based on analysis of different data as environmental and lifestyle, clinical (sperm count, morphology, hormone testing, karyotype, etc.) and "omics" bigdata. Ultimately, the development of AI algorithms will assist clinicians in formulating diagnosis, making treatment decisions, and predicting outcomes for assisted reproduction techniques.

Cystic fibrosis transmembrane conductance regulator (CFTR): beyond cystic fibrosis

Background

The cystic fibrosis transmembrane conductance regulator (CFTR) gene has been traditionally linked to cystic fibrosis (CF) inheritance in an autosomal recessive manner. Advances in molecular biology and genetics have expanded our understanding of the CFTR gene and its encoding products expressed in different tissues.

Aim

The study’s aim consists of reviewing the different pathological CF phenotypes using the existing literature. We know that alterations of the CFTR protein’s structure may result in different pathological phenotypes.

Methods

Open sources such as PubMed and Science Direct databases have been used for this review. We focused our selection on articles published within the last 15 years. Critical terms related to the CFTR protein have been used: “CFTR AND cancer,” “CFTR AND celiac disease,” “CFTR AND pancreatitis,” “children,” “adults,” “genotype,” “phenotype,” “correlation,” “mutation,”  “CFTR,” “diseases,” “disorders,” and “no cystic fibrosis.”

Results

We analyzed 1,115 abstracts in total. Moreover, only 189 were suitable for the topic. We focused on the role of CFTR in cancer, gastrointestinal disorders, respiratory diseases, reproductive system, and systemic hypertension.

Conclusions

Mutations in CFTR gene are often associated with CF. In this review, we highlighted the broad spectrum of alterations reported for this gene, which may be involved in the pathogenesis of other diseases. The importance of these new insights in the role of CFTR relies on the possibility of considering this protein/gene as a novel therapeutic target for CF- and CFTR-related diseases.

The prevalence of common CFTR gene mutations and polymorphisms in infertile Iranian men with very severe oligozoospermia

Due to progress in infertility etiology, several genetic bases of infertility are revealed today. This study aimed to investigate the distribution of mutations in the CFTR gene, M470V polymorphism, and IVS8 poly T. Furthermore, we aimed to examine the hotspot exons (4, 7, 9, 10, 11, 20, and 21 exons) to find a new mutation in cystic fibrosis transmembrane conductance regulator (CFTR) gene among infertile Iranian men very severe oligozoospermia (<1 million sperm/mL ejaculate fluid). In the present case-control study, 200 very severe oligozoospermia (20-60s) and 200 fertile men (18-65s) were registered. Five common CFTR mutations were genotyped using the ARMS-PCR technique. The M470V polymorphism was checked out by real-time PCR, and poly T and exons were sequenced. The F508del was the most common (4.5%) CFTR gene mutation; G542X and W1282X were detected with 1.5% and 1%, respectively. N1303K and R117H were detected in 0.5% of cases. F508del was seen as a heterozygous compound with G542X in one patient and with W1282X in the other patient. Also, in the case of M470V polymorphism, there are differences between the case and control groups (p=0.013). Poly T assay showed statistical differences in some genotypes. The study showed no new mutation in the exons mentioned above. Our results shed light on the genetic basis of men with very severe oligozoospermia in the Iranian population, which will support therapy decisions among infertile men.

Genetic analysis and intracytoplasmic sperm injection outcomes of Chinese patients with congenital bilateral absence of vas deferens

PURPOSE

Congenital bilateral absence of the vas deferens (CBAVD) is a major cause of obstructive azoospermia and male factor infertility. CBAVD is mainly caused by mutations in the genes encoding CFTR (cystic fibrosis transmembrane conductance regulator) and ADGRG2 (adhesion G protein-coupled receptor G2). This study aimed to describe CFTR and ADGRG2 variations in 46 Chinese CBAVD patients and evaluated sperm retrieval and assisted reproductive technology outcomes.

METHODS

The CFTR and ADGRG2 genes were sequenced and analyzed by whole-exome sequencing (WES), and variations were identified by Sanger sequencing. Bioinformatic analysis was performed. We retrospectively reviewed the outcomes of patients undergoing sperm retrieval surgery and intracytoplasmic sperm injection (ICSI).

RESULTS

In total, 35 of 46 (76.09%) patients carried at least one variation in CFTR, but no copy number variants or ADGRG2 variations were found. In addition to the IVS9-5 T allele, there were 27 CFTR variations, of which 4 variations were novel and predicted to be damaging by bioinformatics. Spermatozoa were successfully retrachieved in 46 patients, and 39 of the patients had their own offspring through ICSI.

CONCLUSION

There are no obvious hotspot CFTR mutations in Chinese CBAVD patients besides the IVS9-5 T allele. Therefore, WES might be the best detection method, and genetic counseling should be different from that provided to Caucasian populations. After proper counseling, all patients can undergo sperm retrieval from their epididymis or testis, and most of them can have their own children through ICSI.

Congenital Bilateral Absence of the Vas Deferens

Congenital bilateral absence of the vas deferens (CBAVD) is clinically characterized by the absence of the bilateral vas deferens; the main clinical manifestation is infertility, accounting for 1–2% of male infertility cases. CBAVD may be accompanied by congenital abnormalities in the urogenital system and cystic fibrosis (CF)-related clinical manifestations. CBAVD can develop as a mild manifestation of CF or can be isolated. The main pathogenic mechanism of CBAVD is gene mutation, and CBAVD and CF have a common genetic mutation background. CFTR mutation is the main pathogenic cause of CBAVD and CF, and ADGRG2 mutation is the second most common cause. Although lack of the vas deferens in CBAVD patients causes infertility due to the inability to release sperm, the testes of CBAVD patients have spermatogenic function. Therefore, CBAVD patients can achieve fertility through sperm retrieval surgery and assisted reproductive technology (ART). However, gene mutations in CBAVD patients can have an impact on the ART outcome, and there is a risk of passing on gene mutations to offspring. For CBAVD patients and their spouses, performing genetic counseling (which currently refers mainly to CFTR mutation screening) helps to reduce the risks of genetic mutations being passed on to offspring and of offspring having CF with concomitant CBAVD.

Identification and selection of healthy spermatozoa in heterozygous carriers of the Phe508del-variant of the CFTR-gene in assisted reproduction

The pathogenic variant Phe508del of the CFTR-gene is the most frequent cause of cystic fibrosis (CF). Whereas male CF-patients are infertile due to bilateral agenesis of the efferent ducts, the fertility status of male heterozygous carriers is uncertain. We aimed at demonstrating the involvement of the CFTR-ion channel during sperm capacitation and to potentially select variant-free spermatozoa in heterozygous carriers of the CFTR-variant using flow cytometry (FC). Using FC and sorting, single cell polymerase chain reaction, immuno-fluorescent staining an experimental study was performed on nine fertile semen donors and three heterozygous infertile men carrying the Phe508del gene variant. Chemical inhibition of CFTR interfered with sperm capacitation. Most viable spermatozoa of heterozygous carriers of the Phe508del variant of the CFTR-gene show immune-fluorescent CFTR. Sperm capacitation in Phe508del carriers was similar to that in healthy semen donors. Distribution of the Phe508del allele in trio data of CF-affected families corresponded to the expected recessive inheritance pattern. Infertility in Phe508del heterozygous men is unlikely to be caused by the pathogenic variant although some contribution cannot be excluded. Normal sperm capacitation in carriers of pathogenic variants of the Phe508del-gene may in part explain the high prevalence of a potentially lethal recessive disorder.

A patient with 47, XYY mosaic karyotype and congenital absence of bilateral vas deferens: a case report and literature review

Background

The incidence of 47, XYY syndrome in live-born male infants is 1/1000. Due to its variable clinical symptoms, the diagnosis is easy to miss. The incidence of congenital bilateral absence of the vas deferens (CBAVD) in infertile men is 1–2%. The main cause is the mutation of CFTR and ADGAG2 genes.

Case presentation

The patient was a 33-year-old man who visited a doctor 5 years ago due to infertility. The investigation revealed that the patient’s secondary sexual characteristics, testicular, and penis development were normal, and there was no gynecomastia, but the bilateral vas deferens and epididymis were not palpable. Transrectal ultrasound showed that the left seminal vesicle was missing, and the right seminal vesicle was atrophied. No abnormality was observed in Y chromosome microdeletion. Karyotype analysis indicated that the patient was 46, XY/47, XYY mosaic. Genetic testing found heterozygous mutations at two sites of CFTR (c263T > G and c2249C > T).

Conclusions

Herein, we report the rare case of a male patient with clinical manifestations of infertility, chromosome 46, XY/47, XXY mosaic type, simultaneously manifested as the absence of bilateral vas deferens. Two pathogenic heterozygous CFTR gene mutations were found. Given the low genetic risk of the disease, we recommend that patients undergo intracytoplasmic sperm injection (ICSI) for fertility assessment.

The indispensable role of pharmacy services and medication therapy management in cystic fibrosis

Care for people with cystic fibrosis (PWCF) is highly complex and requires a multidisciplinary approach where the pharmacist plays a vital role. The purpose of this manuscript is to serve as a guideline for pharmacists and pharmacy technicians who provide care for PWCF by providing background and current recommendations for the use of cystic fibrosis (CF)-specific medications in both the acute and ambulatory care settings. The article explores current literature surrounding the role of pharmacists and pharmacy technicians, proven pharmacy models to emulate, and pharmacokinetic idiosyncrasies unique to the CF population while also identifying areas of future research. Clinical recommendations for the use of CF-specific medications are broken down by organ system including mechanism of action, adverse events, dosages, and monitoring parameters. The article also includes quick reference tables essential to the acute and chronic medication therapy management of PWCF.

Compendium of causative genes and their encoded proteins for common monogenic disorders

A compendium is presented of inherited monogenic disorders that have a prevalence of >1:20,000 in the human population, along with their causative genes and encoded proteins. "Simple" monogenic diseases are those for which the clinical features are caused by mutations impacting a single gene, usually in a manner that alters the sequence of the encoded protein. Of course, for a given "monogenic disorder", there is sometimes more than one potential disease gene, mutations in any one of which is sufficient to cause phenotypes of that disorder. Disease-causing mutations for monogenic disorders are usually passed on from generation to generation in a Mendelian fashion, and originate from spontaneous (de novo) germline founder mutations. In the past monogenic disorders have often been written off as targets for drug discovery because they sometimes are assumed to be rare disorders, for which the meager projected financial payoff of drug discovery and development has discouraged investment. However, not all monogenic diseases are rare. Here, we report that that currently available data identifies 72 disorders with a prevalence of at least 1 in 20,000 humans. For each, we tabulate the gene(s) for which mutations cause the spectrum of phenotypes associated with that disorder. We also identify the gene and protein that most commonly causes each disease. 34 of these disorders are caused exclusively by mutations in only a single gene and encoded protein.

Immunoglobulin A Mucosal Immunity and Altered Respiratory Epithelium in Cystic Fibrosis

The respiratory epithelium represents the first chemical, immune, and physical barrier against inhaled noxious materials, particularly pathogens in cystic fibrosis. Local mucus thickening, altered mucociliary clearance, and reduced pH due to CFTR protein dysfunction favor bacterial overgrowth and excessive inflammation. We aimed in this review to summarize respiratory mucosal alterations within the epithelium and current knowledge on local immunity linked to immunoglobulin A in patients with cystic fibrosis.

European Association of Urology Guidelines on Male Sexual and Reproductive Health: 2021 Update on Male Infertility

CONTEXT

The European Association of Urology (EAU) has updated its guidelines on sexual and reproductive health for 2021.

OBJECTIVE

To present a summary of the 2021 version of the EAU guidelines on sexual and reproductive health, including advances and areas of controversy in male infertility.

EVIDENCE ACQUISITION

The panel performed a comprehensive literature review of novel data up to January 2021. The guidelines were updated and a strength rating for each recommendation was included that was based either on a systematic review of the literature or consensus opinion from the expert panel, where applicable.

EVIDENCE SYNTHESIS

The male partner in infertile couples should undergo a comprehensive urological assessment to identify and treat any modifiable risk factors causing fertility impairment. Infertile men are at a higher risk of harbouring and developing other diseases including malignancy and cardiovascular disease and should be screened for potential modifiable risk factors, such as hypogonadism. Sperm DNA fragmentation testing has emerged as a novel biomarker that can identify infertile men and provide information on the outcomes from assisted reproductive techniques. The role of hormone stimulation therapy in hypergonadotropic hypogonadal or eugonadal patients is controversial and is not recommended outside of clinical trials. Furthermore, there is insufficient evidence to support the widespread use of other empirical treatments and surgical interventions in clinical practice (such as antioxidants and surgical sperm retrieval in men without azoospermia). There is low-quality evidence to support the routine use of testicular fine-needle mapping as an alternative diagnostic and predictive tool before testicular sperm extraction (TESE) in men with nonobstructive azoospermia (NOA), and either conventional or microdissection TESE remains the surgical modality of choice for men with NOA.

CONCLUSIONS

All infertile men should undergo a comprehensive urological assessment to identify and treat any modifiable risk factors. Increasing data indicate that infertile men are at higher risk of cardiovascular mortality and of developing cancers and should be screened and counselled accordingly. There is low-quality evidence supporting the use of empirical treatments and interventions currently used in clinical practice; the efficacy of these therapies needs to be validated in large-scale randomised controlled trials.

PATIENT SUMMARY

Approximately 50% of infertility will be due to problems with the male partner. Therefore, all infertile men should be assessed by a specialist with the expertise to not only help optimise their fertility but also because they are at higher risk of developing cardiovascular disease and cancer long term and therefore require appropriate counselling and management. There are many treatments and interventions for male infertility that have not been validated in high-quality studies and caution should be applied to their use in routine clinical practice.

"Fertility and Pregnancy in Cystic fibrosis"

People with Cystic fibrosis (pwCF) have experienced increased survival and wellbeing in recent decades, such that more than half of those living with CF are adults. Consequently, sexual and reproductive health is increasingly important for pwCF as many are considering parenthood. Most men and some women with CF (wwCF) will have reduced fertility, which in both sexes is multifactorial. However, unplanned pregnancies in women are not rare, and contraception and its interaction with CF complications need to be addressed by the CF team. Reduced fertility may be overcome in most pwCF through use of assisted reproductive technologies; however, the risk of having offspring with CF must be considered. Most wwCF will have normal pregnancies, but premature birth is common especially in the setting of reduced lung function and CF related diabetes (CFRD); optimization of treatment is recommended during pregnancy planning. Parenting imposes an increased burden on pwCF, with the challenges of caring for the newborn, postpartum physiologic changes and maintaining CF treatments. Most drugs used to treat CF are considered safe in pregnancy and lactation, but exceptions need to be acknowledged, including the limited data regarding safety of CF transmembrane conductance regulator (CFTR) modulators during conception, pregnancy, and lactation. As most pwCF are eligible for highly effective CFTR modulators, fertility, contraception, and pregnancy in people with CF is changing. Prospective studies regarding these issues in people treated with CFTR modulators are paramount to provide evidence-based guidance for management in the current era of CF care.

Cystic fibrosis transmembrane conductance regulator-related male infertility: Relevance of genetic testing & counselling in Indian population

Background & objectives:

Due to limited information available on the frequency and spectrum of cystic fibrosis (CF) transmembrane conductance regulator (CFTR) gene mutations in congenital bilateral absence of vas deferens (CBAVD) in Indian population, it is difficult to provide accurate genetic counselling to couples. The present study was undertaken to investigate the spectrum and frequency of CFTR gene mutations in Indian men with CBAVD and to determine the female CF carrier status.

Methods:

Direct DNA sequencing of the CFTR gene was carried out in eighty CBAVD men, their female partners and fifty controls from the general population. Pathological significance of the identified novel CFTR gene variants was carried out using in silico tools. Appropriate genetic counselling was provided to the couples prior to intracytoplasmic sperm injection (ICSI).

Results:

A significant association was observed for CFTR gene variants in Indian CBAVD men versus controls (odds ratio: 12.1; 95% confidence interval: 4.8-30.4; P<0.0001). A total of 20 CFTR gene variants were identified in 53 CBAVD men. Eight novel missense CFTR gene variants (L214V, A238P, E379V, L578I, F587L, L926W, R1325K and R1453Q); two novel splice-site gene variants (c.1-30C>G and IVS1+2T>G) and ten previously reported mutations (R75Q, c.1210-12[5], F508del, A309G, R334W, I444T, R668C, R709X, A1285V and Q1352H) were detected in CBAVD men. The novel and reported CFTR gene mutations were L926W (2.5%, P=0.26), R1453Q (2.5%, P=0.26), F508del (8.75%, P=0.03) and c.1210-12[5] (42.5%, P=0.002). A total of 13 (16.2%) female partners were found to be a CF carrier. Nine couples had a risk of transmitting mutant CFTR allele to the offspring.

Interpretation & conclusions:

The heterogeneous spectrum of CFTR gene in Indian population suggests the necessity of screening CBAVD men and female partners for accurate genetic counselling prior to undergoing ICSI.

Genetics of CFTR and male infertility

Cystic fibrosis (CF) is a rare autosomal-recessive disorder manifested as multisystem organ dysfunction. The cystic fibrosis transmembrane conductance regulator (CFTR) protein functions as an ion transporter on the epithelium of exocrine glands, regulating secretion viscosity. The CFTR gene, encoded on chromosome 7, is required for the production and trafficking of the intact and functional CFTR protein. Literally thousands of human CFTR allelic mutations have been identified, each with varying impact on protein quality and quantity. As a result, individuals harboring CFTR mutations present with a spectrum of symptoms ranging from CF to normal phenotypes. Those with loss of function but without full CF may present with CFTR-related disorders (CFTR-RDs) including male infertility, sinusitis, pancreatitis, atypical asthma and bronchitis. Studies have demonstrated associations between higher rates of CFTR mutations and oligospermia, epididymal obstruction, congenital bilateral absence of the vas deferens (CBAVD), and idiopathic ejaculatory duct obstruction (EDO). Genetic variants are detected in over three-quarters of men with CBAVD, the reproductive abnormality most classically associated with CFTR aberrations. Likewise, nearly all men with clinical CF will have CBAVD. Current guidelines from multiple groups recommend CFTR screening in all men with clinical CF or CBAVD though a consensus on the minimum number of variants for which to test is lacking. CFTR testing is not recommended as routine screening for men with other categories of infertility. While available CFTR panels include 30 to 96 of the most common variants, complete gene sequencing should be considered if there is a high index of suspicion in a high-risk couple (e.g., partner is CFTR mutation carrier). CF treatments to date have largely targeted end-organ complications. Novel CFTR-modulator treatments aim to directly target CFTR protein dysfunction, effectively circumventing downstream complications, and possibly preventing symptoms like vasal atresia at a young age. Future gene therapies may also hold promise in preventing or reversing genetic changes that lead to CF and CFTR-RD.

Genetic testing for men with infertility: techniques and indications

Genetic testing is an integral component in the workup of male infertility as genetic conditions may be responsible for up to 15% of all cases. Currently, three genetic tests are commonly performed and recommended by major urologic associations: karyotype analysis (KA), Y-chromosome microdeletion testing, and CFTR mutation testing. Despite widespread adoption of these tests, an etiology for infertility remains elusive in up to 80% of cases. Recent work has identified intriguing new targets for genetic testing which may soon see clinical relevance. This review will discuss the indications and techniques for currently offered genetic tests and briefly explore ongoing research directions within this field.

How do we counsel men with obstructive azoospermia due to CF mutations?-a review of treatment options and outcomes

Obstructive azoospermia (OA) is a rare cause of male infertility, with Congenital Bilateral Absence of The Vas Deferens (CBAVD) being a major cause. A wealth of literature has established an irrefutable link between CFTR mutations and CBAVD, with CBAVD affecting almost all men with cystic fibrosis (CF) disease and a significant portion of men that are CFTR mutation carriers. In the past two decades, assisted reproductive technologies have made the prospect of fathering children a viable possibility in this subset of men, using a combination of sperm extraction techniques and intracystoplasmic sperm injection (ICSI). In order to assess techniques for sperm retrieval, as well as reproductive outcomes, a systemic search of the MEDLINE database was conducted for all articles pertaining to management options for CBAVD, and also all reports describing outcomes of these procedures in the CBAVD population. Both epididymal and testicular sperm extraction (TESE) are viable options for men with CBAVD, and though rigorous data are lacking, live birth rates range from 8% to 50% in most small retrospective series and subset analyses. In addition, there does not appear to be significant differences in the rate of live birth or complications and miscarriages between the various techniques, though further investigation into other factors that limit reproductive potential of men with CFTR mutations and CBAVD is warranted.

Case Report: Japanese Siblings of Cystic Fibrosis With a Novel Large Heterozygous Deletion in the CFTR Gene

Cystic fibrosis (CF) is a rare disease in the Japanese. The most common CFTR variant in Japanese CF patients is a large heterozygous deletion that can easily avoid detection by standard gene sequencing methods. We herein report a novel large heterozygous deletion in the CFTR gene in Japanese siblings with CF. A genetic analysis was performed in two patients (9-year-old boy and 5-month-old girl) who were clinically diagnosed with CF because of the positive result for the rapid fecal pancreatic elastase antigen test and the elevation of the sweat chloride concentration. In addition to conventional polymerase chain reaction (PCR) and direct sequencing, multiplex ligation-dependent probe amplification (MLPA) was performed to check for a large deletion and duplication of the CFTR gene. Based on MLPA findings, the breakpoint of heterozygous deletion was identified by real-time quantitative PCR followed by the sequence of the amplified junction fragment. In MLPA, the numbers of the fragments corresponding to exons 1, 16, 17a, and 17b and 234 nt and 747 nt upstream from the translation initiation codon of exon 1 in the CFTR gene and exon 3 in the ASZ1 gene were reduced by almost half. The c.2908+1085_3367+260del7201 variant (exon 16-17b deletion) was identified in one allele. The other allele had a large 137,567-bp deletion from g.117,361,112 (ASZ1 3' flanking region) to g.117,498,678 (CFTR intron 1) on chromosome 7. Since the deletion variant lacked the entire promoter region of CFTR, CFTR mRNA would not be transcribed from the allele, indicating it to be a novel pathogenic variant causing CF. As large mutations are frequently detected in Japanese CF patients, MPLA can be useful when searching for variants.

[A CASE OF CONGENITAL UNILATERAL ABSENCE OF THE VAS DEFERENS WITH SUSPECTED IPSILATERAL RENAL AGENESIS]

A 5-month-old boy was referred to our department to examine poor development of external genitalia. The patient was diagnosed with micropenis and bilateral impalpable testes, and testosterone replacement therapy was recommended. The testes remained impalpable at 14 months of age; therefore, laparoscopy was performed to explore intra-abdominal testes. The patient was incidentally diagnosed with congenital unilateral absence of the right vas deferens. A renal sonography performed after the operation revealed a high possibility of right renal agenesis. Congenital absence of the vas deferens is associated with a high probability of renal anomalies. It is, therefore, essential to pay careful attention to renal dysfunction.

Male reproductive health in cystic fibrosis

The impact of cystic fibrosis (CF) on male reproductive health is profound. The vast majority of men with CF are infertile due to obstructive azoospermia. Multiple factors associated with CF contribute to an increased prevalence of testosterone deficiency, which adversely affects muscle mass, bone density, and quality of life. This article reviews the pathophysiology, diagnosis, and management of infertility and testosterone deficiency that occur in men with CF. With improving survival of CF patients, these topics are becoming more significant in their clinical care.

Congenital absence of the vas deferens: Cystic fibrosis transmembrane regulatory gene mutations

Congenital absence of the vas deferens (CAVD) is a rare genetic condition first discovered in the mid-18th century related to mutations in the cystic fibrosis transmembrane regulatory genes. The condition is typically found during work-up of male infertility, and the majority of cases can be diagnosed with complete history and physical examination and pertinent investigations. The condition can be separated into three subcategories, and genetic advances have led to a much better understanding behind the disease, its pathogenesis, and options for treatment. In this review, we discuss the genetics, pathogenesis, embryology, and diagnosis of treatment of CAVD. Future work in this area likely will aim to better understand the epigenetic factors that influence the development of the condition in order to identify potential upstream therapeutic targets.

Diagnosis and Treatment of Male Infertility-Related Fertilization Failure

Infertility affects approximately 15% of reproductive-aged couples worldwide, of which up to 30% of the cases are caused by male factors alone. The origin of male infertility is mostly attributed to sperm abnormalities, of which many are caused by genetic defects. The development of intracytoplasmic sperm injection (ICSI) has helped to circumvent most male infertility conditions. However, there is still a challenging group of infertile males whose sperm, although having normal sperm parameters, are unable to activate the oocyte, even after ICSI treatment. While ICSI generally allows fertilization rates of 70 to 80%, total fertilization failure (FF) still occurs in 1 to 3% of ICSI cycles. Phospholipase C zeta (PLCζ) has been demonstrated to be a critical sperm oocyte activating factor (SOAF) and the absence, reduced, or altered forms of PLCζ have been shown to cause male infertility-related FF. The purpose of this review is to (i) summarize the current knowledge on PLCζ as the critical sperm factor for successful fertilization, as well as to discuss the existence of alternative sperm-induced oocyte activation mechanisms, (ii) describe the diagnostic tests available to determine the cause of FF, and (iii) summarize the beneficial effect of assisted oocyte activation (AOA) to overcome FF.

Sperm ion channels and transporters in male fertility and infertility

Mammalian sperm cells must respond to cues originating from along the female reproductive tract and from the layers of the egg in order to complete their fertilization journey. Dynamic regulation of ion signalling is, therefore, essential for sperm cells to adapt to their constantly changing environment. Over the past 15 years, direct electrophysiological recordings together with genetically modified mouse models and human genetics have confirmed the importance of ion channels, including the principal Ca²⁺-selective plasma membrane ion channel CatSper, for sperm activity. Sperm ion channels and membrane receptors are attractive targets for both the development of contraceptives and infertility treatment drugs. Furthermore, in this era of assisted reproductive technologies, understanding the signalling processes implicated in defective sperm function, particularly those arising from genetic abnormalities, is of the utmost importance not only for the development of infertility treatments but also to assess the overall health of a patient and his children. Future studies to improve reproductive health care and overall health care as a function of the ability to reproduce should include identification and analyses of gene variants that underlie human infertility and research into fertility-related molecules.

Prevalence of CBAVD in azoospermic men carrying pathogenic CFTR mutations - Evaluated in a cohort of 639 non-vasectomized azoospermic men

BACKGROUND

Men with obstructive azoospermia (OA) due to impaired development of the genital tract often carry at least one Cystic Fibrosis Transmembrane Conductance Regulator CFTR mutation.

OBJECTIVE

To determine the frequency of Congenital Bilateral Absence of Vas deferens (CBAVD) in men with azoospermia carrying CFTR gene mutations.

MATERIALS AND METHODS

Non-vasectomized men with azoospermia referred to our andrological center were consecutively included. All men underwent palpation of the scrotal parts of the Vasa deferentia, ultrasonography of the testicles and hormone profile, and genetic analyses. Testicular biopsy was usually performed. A panel of 32 of the most important CFTR mutations was examined from genomic DNA isolated from blood lymphocytes. Either multiplex PCR analysis or a next-generation sequencing technique was performed.

RESULTS

Among the 639 men with azoospermia, 69 (10.8%) had at least one CFTR mutation. Of the 43 patients with at least one of the two CFTR mutations, ΔF508 and R117H, 19 (44.2%) showed CBAVD, 2 (4.7%) Congenital Unilateral Absence of Vas deferens (CUAVD), and 22 (51.2%) presence of the scrotal parts of the Vasa deferentia. In contrast, only 1/21 men (4.8%) with an isolated IVS8-5T variant showed CBAVD. Among the further 20 men with an isolated IVS8-5T variant, 11 had a history of cryptorchidism. Among the 570 men without CFTR mutations, CBAVD was found in only two men and CUAVD in one. FSH level was higher and testicular volume lower in men with present Vasa deferentia compared to those without (P < .001; Student's t test). Thirty-one men with either ΔF508 or R117H mutations, or both, had a testicular biopsy. Motile spermatozoa were found in 100% of 16 cases with CBAVD but in only 6 out of 15 cases with present Vasa deferentia (P < .01; Fisher's exact test).

DISCUSSION AND CONCLUSIONS

CBAVD was found in ~ 44% of men with ΔF508/R117H mutations. The data may support that CFTR mutations might affect male fertility through other mechanisms than obstruction of the genital tract. For a practical, clinical purpose analysis for only ΔF508, R117H and IVS8-5T seems sufficient until further research shows anything else.

Thoughts on the popularity of ICSI

Purpose

Intracytoplasmic sperm injection (ICSI) is the most widely utilized assisted reproductive technique (ART) worldwide. In this feature, we review the early assisted fertilization attempts that eventually led to the development of ICSI, and discuss its current utilization in cases of male and non-male factor infertility.

Methods

We researched the literature related to the development, indications, and current use of ICSI, such as sperm structural abnormalities, male genetic indications, surgically retrieved sperm, high sperm chromatin fragmentation, oocyte dysmorphism, and preimplantation genetic testing (PGT). We also describe the potential future applications of ICSI.

Results

This review summarizes the early micromanipulation techniques that led to the inception of ICSI. We also explore its current indications, including non-male factor infertility, where its use is more controversial. Finally, we consider the benefits of future advancements in reproductive biology that may incorporate ICSI, such as in vitro spermatogenesis, neogametogenesis, and heritable genome editing.

Conclusion

The versatility, consistency, and reliability of ICSI have made it the most prevalently utilized ART procedure worldwide.

Genetic disorders and male infertility

BACKGROUND

At present, one out of six couples is infertile, and in 50% of cases, infertility is attributed to male infertility factors. Genetic abnormalities are found in 10%-20% of patients showing severe spermatogenesis disorders, including non-obstructive azoospermia.

METHODS

Literatures covering the relationship between male infertility and genetic disorders or chromosomal abnormalities were studied and summarized.

MAIN FINDINGS RESULTS

Genetic disorders, including Klinefelter syndrome, balanced reciprocal translocation, Robertsonian translocation, structural abnormalities in Y chromosome, XX male, azoospermic factor (AZF) deletions, and congenital bilateral absence of vas deferens were summarized and discussed from a practical point of view. Among them, understanding on AZF deletions significantly changed owing to advanced elucidation of their pathogenesis. Due to its technical progress, AZF deletion test can reveal their delicate variations and predict the condition of spermatogenesis. Thirty-nine candidate genes possibly responsible for azoospermia have been identified in the last 10 years owing to the advances in genome sequencing technologies.

CONCLUSION

Genetic testing for chromosomes and AZF deletions should be examined in cases of severe oligozoospermia and azoospermia. Genetic counseling should be offered before and after genetic testing.

Analysis of CNVs of CFTR gene in Chinese Han population with CBAVD

Background

Congenital bilateral absence of vas deferens (CBAVD) is an important disease of male infertility, which affects 1%–2% of infertile population. In addition to common mutations of CFTR, copy number variants (CNVs) have also been implicated as one of the pathogenesis of CBAVD. The present study aimed to investigate the genetic contribution of CFTR CNVs in Chinese Han population with CBAVD.

Methods

Two hundred and sixty‐three CBAVD patients were recruited. Genomic DNA was extracted from peripheral blood samples. The Multiplex Ligation‐dependent Probe Amplification assay was performed which targets the region of the CFTR gene.

Results

Among 263 Chinese men affected with CBAVD in this study, 5 (1.90%) patients were detected for copy number variants in the region of CFTR gene (4 of them carried partial deletions and 1 of them carried partial duplication of CFTR gene).

Conclusions

The study showed that the rate of CFTR CNVs in Chinese population with CBAVD were basically consistent with the previous reports. And the study first revealed genetic risk of CNVs of CFTR on a large sample size of CBAVD patients in Chinese Han population, which prompted that it was necessary to detect CNVs of CFTR in Chinese Han people with CBAVD.

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)

Congenital bilateral absence of the vas deferens (CBAVD) is predominantly caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. CBAVD accounts for 2–6% of male infertility cases and up to 25% of cases of obstructive azoospermia. With the use of pre-implantation genetic diagnosis, testicular or epididymal sperm aspiration, intracytoplasmic sperm injection and in vitro fertilization, patients affected by CBAVD are able to have children who do not carry CFTR gene mutations, thereby preventing disease. Therefore, genetic counseling should be provided to couples receiving assisted reproductive techniques to discuss the impact of CFTR gene mutations on reproductive health. In the present article, the current literature concerning the CFTR gene and its association with CBAVD is reviewed.

Mutation analysis of the cystic fibrosis transmembrane conductance regulator gene in Chinese congenital absence of vas deferens patients

To find the variant spectrum of the cystic fibrosis transmembrane conductance regulator (CFTR) gene, and evaluate its frequent variants in Chinese congenital absence of vas deferens (CAVD) patients. A total of 276 patients with azoospermia and CAVD (aged from 21 to 44 years old) were investigated from May 2013 to September 2019 in the Third Affiliated Hospital of Sun Yat-sen University. Additionally, 50 healthy, unrelated volunteers were recruited as controls (aged from 21 to 46 years old). The 5'-UTR, exons and their flanking side of the CFTR gene were sequenced by high-throughput sequencing technology. The results were compared with those retrieved from the Ensembl Genome Browser. In addition, all 13 novel variants were further confirmed independently by Sanger sequencing and evaluated in the bioinformatics web servers. A schematic of the variant spectrum of the CFTR gene, including 13 novel variants (12 in CAVD patients, one in the control group), is shown, and the frequent variants in Chinese CAVD patients were 5 T (27.54%), c.-8G > C (7.25%), p.Q1352H (5.98%), and p.I556V (3.08%). 5 T was found to be the most frequent variant. p.Q1352H had a significantly high allelic frequency in CAVD patients (P < 0.05). c.-8G > C and p.I556V had high allelic frequencies but showed no difference between patients and controls (P > 0.05). p.Q1352H is the most common and important missense variant in Chinese patients with CAVD, while the pathological effects of C.-8G > C and p.I556V may be weak after evaluation.