Achieving an optimal pregnancy outcome through the combined utilization of micro-TESE and ICSI in cryptorchidism associated with a non-canonical splicing variant in RXFP2.

PURPOSE: To identify the genetic cause of a cryptorchidism patient carrying a non-canonical splicing variant highlighted by SPCards platform in RXFP2 and to provide a comprehensive overview of RXFP2 variants with cryptorchidism correlation. METHODS: We identified a homozygous non-canonical splicing variant by whole-exome sequencing and Sanger sequencing in a case with cryptorchidism and non-obstructive azoospermia (NOA). As the pathogenicity of this non-canonical splicing variant remained unclear, we initially utilized the SPCards platform to predict its pathogenicity. Subsequently, we employed a minigene splicing assay to further evaluate the influence of the identified splicing variant. Microdissection testicular sperm extraction (micro-TESE) combined with intracytoplasmic sperm injection (ICSI) was performed. PubMed and Human Genome Variant Database (HGMD) were queried to search for RXFP2 variants. RESULTS: We identified a homozygous non-canonical splicing variant (NM_130806: c.1376-12A > G) in RXFP2, and confirmed this variant caused aberrant splicing of exons 15 and 16 of the RXFP2 gene: 11 bases were added in front of exon 16, leading to an abnormal transcript initiation and a frameshift. Fortunately, the patient successfully obtained his biological offspring through micro-TESE combined with ICSI. Four cryptorchidism-associated variants in RXFP2 from 90 patients with cryptorchidism were identified through a literature search in PubMed and HGMD, with different inheritance patterns. CONCLUSION: This is the first cryptorchidism case carrying a novel causative non-canonical splicing RXFP2 variant. The combined approach of micro-TESE and ICSI contributed to an optimal pregnancy outcome. Our literature review demonstrated that RXFP2 variants caused cryptorchidism in a recessive inheritance pattern, rather than a dominant pattern.

Homozygous SPAG6 variants can induce nonsyndromic asthenoteratozoospermia with severe MMAF.

BACKGROUND: Multiple morphological abnormalities of the sperm flagella (MMAF) is a subtype of severe asthenoteratozoospermia with poorly understood genetic etiology. SPAG6 is a core axonemal component that plays a critical role in the formation of cilia and sperm flagella. Previous studies have reported that mutations in SPAG6 cause primary ciliary dyskinesia (PCD), but the association between SPAG6 gene variants and the MMAF phenotype has not yet been described. METHODS: We performed whole-exome sequencing (WES) in two unrelated Han Chinese men with MMAF. Sanger sequencing was used to validate the candidate variants. Routine semen analysis was carried out according to the WHO guidelines (5th Edition). Sperm morphology was assessed using modified Papanicolaou staining. Scanning and transmission electron microscopy (S/TEM) was performed to observe the ultrastructural defects of the sperm flagella. Western blot analysis and immunofluorescence (IF) of spermatozoa were performed to examine the expression of SPAG6 protein. Assisted fertilization with intracytoplasmic sperm injection (ICSI) was applied. RESULTS: Two homozygous SPAG6 variants were identified by WES and Sanger validation in two patients with MMAF phenotype (F1 II-1: c.308C > A, p. A103D; F2 II-1: c. 585delA, p. K196Sfs*6). Semen analysis showed progressive rates of less than 1%, and most of the spermatozoa presented MMAF by Papanicolaou staining. TEM revealed that the overall axonemal ultrastructure was disrupted and primarily presented an abnormal "9 + 0" configuration. No other PCD-related symptoms were found on physical examination and medical consultations, as well as lung CT screening. The level of SPAG6 protein was significantly decreased in the spermatozoa, and IF analysis revealed that SPAG6 staining was extremely weak and discontinuous in the sperm flagella of the two patients. Notably, F1 II-1 and his wife conceived successfully after undergoing ICSI. CONCLUSIONS: Our research provides new evidence for a potential correlation between SPAG6 variants and the MMAF phenotype.

Identification of deleterious variants in patients with male infertility due to idiopathic non-obstructive azoospermia.

BACKGROUND: Non-obstructive azoospermia (NOA) is the most severe type of male infertility, affecting 1% of men worldwide. Most of its etiologies remain idiopathic. Although genetic studies have identified dozens of NOA genes, monogenic mutations can also account for a small proportion of idiopathic NOA cases. Hence, this genetic study was conducted to explore the causes of monogenic variants of NOA in a cohort of Chinese patients. METHODS: Following the screening using chromosomal karyotyping, Y chromosome microdeletion analyses, and sex hormone assessments, subsequent whole-exome sequencing analysis was performed in 55 unrelated idiopathic NOA patients with male infertility to explore potential deleterious variants associated with spermatogenesis. We also performed Sanger sequencing to demonstrate the variants. Testicular biopsy or microsurgical testicular sperm extraction was also performed to confirm the diagnosis of NOA and identify spermatozoa. Hematoxylin and eosin staining was performed to assess the histopathology of spermatogenesis. RESULTS: Abnormal testicular pathological phenotypes included Sertoli cell-only syndrome, maturation arrest, and hypospermatogenesis. Using bioinformatics analysis, we detected novel variants in two recessive genes, FANCA (NM_000135, c.3263C > T, c.1729C > G) and SYCE1 (NM_001143763, c.689_690del); one X-linked gene, TEX11 (NM_031276, c.466A > G, c.559_560del); and two dominant genes, DMRT1 (NM_021951, c.425C > T, c.340G > A) and PLK4 (NM_001190799, c.2785A > G), in eight patients, which corresponded to 14.55% (8/55) of the patients. CONCLUSION: This study presented some novel variants of known pathogenic genes for NOA. Further, it expanded the variant spectrum of NOA patients, which might advance clinical genetic counseling in the future.

Homozygous mutation in SLO3 leads to severe asthenoteratozoospermia due to acrosome hypoplasia and mitochondrial sheath malformations.

BACKGROUND: Potassium channels are important for the structure and function of the spermatozoa. As a potassium transporter, the mSlo3 is essential for male fertility as Slo3 knockout male mice were infertile with the series of functional defects in sperm cells. However, no pathogenic variant has been detected in human SLO3 to date. Here we reported a human case with homozygous SLO3 mutation. The function of SLO3 in human sperm and the corresponding assisted reproductive strategy are also investigated. METHODS: We performed whole-exome sequencing analysis from a large cohort of 105 patients with asthenoteratozoospermia. The effects of the variant were investigated by quantitative RT-PCR, western blotting, and immunofluorescence assays using the patient spermatozoa. Sperm morphological and ultrastructural studies were conducted using haematoxylin and eosin staining, scanning and transmission electron microscopy. RESULTS: We identified a homozygous missense variant (c.1237A > T: p.Ile413Phe) in the sperm-specific SLO3 in one Chinese patient with male infertility. This SLO3 variant was rare in human control populations and predicted to be deleterious by multiple bioinformatic tools. Sperm from the individual harbouring the homozygous SLO3 variant exhibited severe morphological abnormalities, such as acrosome hypoplasia, disruption of the mitochondrial sheath, coiled tails, and motility defects. The levels of SLO3 mRNA and protein in spermatozoa from the affected individual were reduced. Furthermore, the acrosome reaction, mitochondrial membrane potential, and membrane potential during capacitation were also afflicted. The levels of acrosome marker glycoproteins and PLCζ1 as well as the mitochondrial sheath protein HSP60 and SLO3 auxiliary subunit LRRC52, were significantly reduced in the spermatozoa from the affected individual. The affected man was sterile due to acrosome and mitochondrial dysfunction; however, intra-cytoplasmic sperm injection successfully rescued this infertile condition. CONCLUSIONS: SLO3 deficiency seriously impact acrosome formation, mitochondrial sheath assembly, and the function of K+ channels. Our findings provided clinical implications for the genetic and reproductive counselling of affected families.

Bi-allelic variants in DNAH10 cause asthenoteratozoospermia and male infertility.

PURPOSE: Multiple morphological abnormalities in the sperm flagella (MMAF) comprise a severe phenotype of asthenoteratozoospermia with reduced or absent spermatozoa motility. Whereas dozens of candidate pathogenic genes for MMAF have been identified, the genetic cause in a large proportion of patients is unknown. We attempted to identify novel genetic explanations for MMAF. METHODS: We performed whole-exome sequencing of patients with MMAF to identify pathogenic variants. The phenotypes of spermatozoa in patients carrying DNAH10 variants were investigated using haematoxylin and eosin staining, scanning electron microscopy, and transmission electron microscopy. The expression and location of DNAH10 and other spermatozoa structure-related proteins were analyzed using immunofluorescence assays. RESULTS: We found one homozygous frameshift DNAH10 variant (NM_207437: c.2514delG:p.L839*) and one compound heterozygous DNAH10 variant (NM_207437: c.10820 T > C:p.M3607T; c.12692C > T:p.T4231I) in two patients with MMAF. These variants were absent or rare in the general population. Haematoxylin and eosin staining and scanning electron microscopy revealed the significant disruption of sperm flagella in the patients. In addition, ultrastructural analysis by transmission electron microscopy showed significant inner dynein arm (IDA) deficiency in sperm flagella. Using immunofluorescence assays, we found a significant reduction in IDA-related proteins including DNAH10 and DNAH1. CONCLUSIONS: We identified putative novel pathogenic variants in DNAH10 for MMAF, which might advance the genetic diagnosis and clinical genetic counselling for male infertility.

Identification of deleterious variants in nine polycystic kidney disease affected families.

Polycystic kidney disease (PKD) is common genetic renal disorder. In present study, we performed WES to identify pathogenic variant in nine families including 26 patients with PKD and 19 unaffected members. The eight pathogenic variants were identified in known PKD associated genes including PKD1 (n = 6), PKD2 (n = 1), and OFD1 (n = 1) in eight families. There is one missense, one stopgain, two non-frameshifts, two canonical splicing variants, three frameshift variants and one potential non-canonical splicing variant (NCSV) in 8 families. The six variants were novel variants and not reported in ClinVar database. In addition, the compound heterozygous variants in PKHD1 were identified including one frameshift variants (PKHD1: NM_138694.4, c.9841del, p.S3281Lfs*4) and one non-canonical splicing variant (PKHD1: NM_138694.4, c.6332 + 40A > G) which were defined as deleterious variant by four splicing prediction tools (CADD-splice, SpliceAI, Spliceogen, Squirl). We used the minigene method to validate whether the prioritized potential NSCVs disrupt the typical mRNA splicing process and found abnormally larger PCR production of minigene carrying potential NCSV comparing to wild-type minigene. Sanger sequencing confirmed the 39-bp insertion of intron 38 between exon 38 and exon 39, which results in non-frameshift and 13 amino acid insertions. In conclusion, our study expands the variant spectrum and highlight the important role of non-canonical splicing variant in PKD.

Association of FOXL2 and ERCC6 variants with premature ovarian insufficiency and their potential use in clinical IVF guidance.

Premature ovarian insufficiency (POI) is the main cause of infertility in women. Some cases of POI are thought to be caused by genetic defects and the clinical outcomes of these patients are unknown. Here, we performed whole-exome sequencing of the peripheral blood of a cohort of 55 subjects with POI and identified one heterozygous missense variant in FOXL2 (c.1045G>C; p.Arg349Gly) and two heterozygous missense variants in ERCC6 (c.379G>A; p.Val127Ile and c.4223A>C; p.Glu1408 Ala) in four POI patients. All of these heterozygous mutations were predicted to be deleterious and were parentally inherited from their heterozygous fathers. The mRNA and protein expression of FOXL2 and ERCC6 were absent or decreased in the patients. The patients carrying the variants of FOXL2 (c.1045G>C; p.Arg349Gly) and ERCC6 (c.379G>A; p.Val127Ile) failed to conceive in two and four assisted reproductive cycles, respectively. Another patient and her sister carrying the ERCC6 (c.4223A>C; p.Glu1408 Ala) variant achieved good clinical outcomes after assisted reproductive therapy. Our findings support the possible roles of FOXL2 and ERCC6 in POI and might contribute to the genetic counseling of POI patients.

Novel variants in DNAH6 cause male infertility associated with multiple morphological abnormalities of the sperm flagella (MMAF) and ICSI outcomes.

Variations in the dynein axonemal heavy chain gene, dynein axonemal heavy chain 6 (DNAH6), lead to multiple morphological abnormalities of the flagella. Recent studies have reported that these deficiencies may result in sperm head deformation. However, whether DNAH6 is also involved in human acrosome biogenesis remains unknown. The purpose of this study was to investigate DNAH6 gene variants and their potential functions in the formation of defective sperm heads and flagella. Whole-exome sequencing was performed on a cohort of 375 patients with asthenoteratozoospermia from the First Affiliated Hospital of Anhui Medical University (Hefei, China). Hematoxylin and eosin staining, scanning electron microscopy, and transmission electron microscopy were performed to analyze the sperm morphology and ultrastructure. Immunofluorescence staining and Western blot analysis were conducted to examine the effects of genetic variants. We identified three novel deleterious variants in DNAH6 among three unrelated families. The absence of inner dynein arms and radial spokes was observed in the sperm of patients with DNAH6 variants. Additionally, deficiencies in the acrosome, abnormal chromatin compaction, and vacuole-containing sperm heads were observed in these patients with DNAH6 variants. The decreased levels of the component proteins in these defective structures were further confirmed in sperm from patients with DNAH6 variants using Western blot. After intracytoplasmic sperm injection (ICSI) treatment, the partner of one patient with a DNAH6 variant achieved successful pregnancy. Overall, novel variants in DNAH6 genes that contribute to defects in the sperm head and flagella were identified, and the findings indicated ICSI as an effective clinical treatment for such patients.

Novel HYDIN variants associated with male infertility in two Chinese families.

Introduction: Infertility is a major disease affecting human life and health, among which male factors account for about half. Asthenoteratozoospermia accounts for the majority of male infertility. High-throughput sequencing techniques have identified numerous variants in genes responsible for asthenoteratozoospermia; however, its etiology still needs to be studied. Method: In this study, we performed whole-exome sequencing on samples from 375 patients with asthenoteratozoospermia and identified two HYDIN compound heterozygous variants, a primary ciliary dyskinesia (PCD)-associated gene, in two unrelated subjects. H&E staining, SEM were employed to analyze the varies on sperm of patients, further, TEM was employed to determine the ultrastructure defects. And westernblot and immunostaining were chose to evaluate the variation of structural protein. ICSI was applied to assist the mutational patient to achieve offspring. Result: We identified two HYDIN compound heterozygous variants. Patient AY078 had novel compound heterozygous splice variants (c.5969-2A>G, c.6316+1G>A), altering the consensus splice acceptor site of HYDIN. He was diagnosed with male infertility and PCD, presenting with decreased sperm progressive motility and morphological abnormalities, and bronchial dilatation in the inferior lobe. Compared to the fertile control, HYDIN levels, acrosome and centrosome markers (ACTL7A, ACROSIN, PLCζ1, and Centrin1), and flagella components (TOMM20, SEPT4, SPEF2, SPAG6, and RSPHs) were significantly reduced in HYDIN-deficient patients. Using intracytoplasmic sperm injection (ICSI), the patient successfully achieved clinical pregnancy. AY079 had deleterious compound heterozygous missense variants, c.9507C>G (p. Asn3169Lys) and c.14081G>A (p. Arg4694His), presenting with infertility; however, semen samples and PCD examination were unavailable. Discussion: Our findings provide the first evidence that the loss of HYDIN function causes asthenoteratozoospermia presenting with various defects in the flagella structure and the disassembly of the acrosome and neck. Additionally, ICSI could rescue this failure of insemination caused by immobile and malformed sperm induced by HYDIN deficiency.

Novel FSIP2 Variants Induce Super-Length Mitochondrial Sheath and Asthenoteratozoospermia in Humans.

Asthenoteratozoospermia is one of the major factors for male infertility, whereas the causes of large numbers of cases are still unknown. We identified compound heterozygous variants of FSIP2 in three unrelated individuals from a cohort of 105 patients with asthenoteratozoospermia by exome sequencing. Deleterious FSIP2 variations caused severe disassembly of the fibrous sheath and axonemal defects. Intriguingly, spermatozoa in our study manifested "super-length" mitochondrial sheaths, increased levels of the mitochondrial sheath outer membrane protein TOMM20 and decreased mitochondrial ATP consumption. Dislocation or deletion of the annulus and reduction or dislocation of the annulus protein SEPT4 were also observed. While the lengthened mitochondrial sheaths were not presented in men harboring SEPT4 variants. Furthermore, female partners of two of three men achieved successful pregnancies following intracytoplasmic sperm injection (ICSI). Overall, we presume that FSIP2 may not only serve as a structural protein of the fibrous sheath but also as an intra-flagellar transporter involving in the axonemal assembly, mitochondrial selection and the termination of mitochondrial sheath extension during spermatogenesis, and ICSI is an effective treatment for individuals with FSIP2-associated asthenoteratozoospermia.