Bi-allelic variants in DNHD1 cause flagellar axoneme defects and asthenoteratozoospermia in humans and mice.

Asthenoteratozoospermia, defined as reduced sperm motility and abnormal sperm morphology, is a disorder with considerable genetic heterogeneity. Although previous studies have identified several asthenoteratozoospermia-associated genes, the etiology remains unknown for the majority of affected men. Here, we performed whole-exome sequencing on 497 unrelated men with asthenoteratozoospermia and identified DNHD1 bi-allelic variants from eight families (1.6%). All detected variants were predicted to be deleterious via multiple bioinformatics tools. Hematoxylin and eosin (H&E) staining revealed that individuals with bi-allelic DNHD1 variants presented striking abnormalities of the flagella; transmission electron microscopy (TEM) further showed flagellar axoneme defects, including central pair microtubule (CP) deficiency and mitochondrial sheath (MS) malformations. In sperm from fertile men, DNHD1 was localized to the entire flagella of the normal sperm; however, it was nearly absent in the flagella of men with bi-allelic DNHD1 variants. Moreover, abundance of the CP markers SPAG6 and SPEF2 was significantly reduced in spermatozoa from men harboring bi-allelic DNHD1 variants. In addition, Dnhd1 knockout male mice (Dnhd1‒/‒) exhibited asthenoteratozoospermia and infertility, a finding consistent with the sperm phenotypes present in human subjects with DNHD1 variants. The female partners of four out of seven men who underwent intracytoplasmic sperm injection therapy subsequently became pregnant. In conclusion, our study showed that bi-allelic DNHD1 variants cause asthenoteratozoospermia, a finding that provides crucial insights into the biological underpinnings of this disorder and should assist with counseling of affected individuals.

Homozygous pathogenic variants in ACTL9 cause fertilization failure and male infertility in humans and mice.

Total fertilization failure (TFF) can occur during in vitro fertilization (IVF) treatments, even following intracytoplasmic sperm injection (ICSI). Various male or female factors could contribute to TFF. Increasing evidence suggested that genetic variations in PLCZ1, which encodes 1-phosphatidylinositol 4,5-bisphosphate phosphodiesterase zeta-1 (PLCζ), is involved in oocyte activation and is a key male factor in TFF. In the present study, we explored the genetic variants in male individuals that led to TFF. A total of 54 couples with TFF or poor fertilization (fertilization rate < 20%) were screened, and 21 couples were determined to have a male infertility factor by the mouse oocyte activation test. Whole-exome sequencing of these 21 male individuals identified three homozygous pathogenic variants in ACTL9 (actin like 9) in three individuals. ACTL9 variations led to abnormal ultrastructure of the perinuclear theca (PT), and PLCζ was absent in the head and present in the neck of the mutant sperm, which contributed to failed normal calcium oscillations in oocytes and subsequent TFF. The key roles of ACTL9 in the PT structure and TFF after ICSI were further confirmed in an Actl9-mutated mouse model. Furthermore, assisted oocyte activation by calcium ionophore exposure successfully overcame TFF and achieved live births in a couple with an ACTL9 variant. These findings identified the role of ACTL9 in the PT structure and the correct localization of PLCζ. The results also provide a genetic marker and a therapeutic option for individuals who have undergone ICSI without successful fertilization.

Bi-allelic mutations of DNAH10 cause primary male infertility with asthenoteratozoospermia in humans and mice.

Multiple morphological abnormalities of the sperm flagella (MMAF)-induced asthenoteratozoospermia is a common cause of male infertility. Previous studies have identified several MMAF-associated genes, highlighting the condition's genetic heterogeneity. To further define the genetic causes underlying MMAF, we performed whole-exome sequencing in a cohort of 643 Chinese MMAF-affected men. Bi-allelic DNAH10 variants were identified in five individuals with MMAF from four unrelated families. These variants were either rare or absent in public population genome databases and were predicted to be deleterious by multiple bioinformatics tools. Morphological and ultrastructural analyses of the spermatozoa obtained from men harboring bi-allelic DNAH10 variants revealed striking flagellar defects with the absence of inner dynein arms (IDAs). DNAH10 encodes an axonemal IDA heavy chain component that is predominantly expressed in the testes. Immunostaining analysis indicated that DNAH10 localized to the entire sperm flagellum of control spermatozoa. In contrast, spermatozoa from the men harboring bi-allelic DNAH10 variants exhibited an absence or markedly reduced staining intensity of DNAH10 and other IDA components, including DNAH2 and DNAH6. Furthermore, the phenotypes were recapitulated in mouse models lacking Dnah10 or expressing a disease-associated variant, confirming the involvement of DNAH10 in human MMAF. Altogether, our findings in humans and mice demonstrate that DNAH10 is essential for sperm flagellar assembly and that deleterious bi-allelic DNAH10 variants can cause male infertility with MMAF. These findings will provide guidance for genetic counseling and insights into the diagnosis of MMAF-associated asthenoteratozoospermia.

SARS-CoV-2 infection is detrimental to pregnancy outcomes after embryo transfer in IVF/ICSI: a prospective cohort study.

BACKGROUND: To explore whether SARS-CoV-2 infection affects the pregnancy outcomes of assisted reproductive techniques (ART). METHODS: A prospective cohort study recruited patients for embryo transfer from December 01, 2022, to December 31, 2022. All patients were closely followed up for SARS-CoV-2 infection after embryo transfer. The SARS-CoV-2 "diagnosed group" was defined as RNA or antigen-positive. The SARS-CoV-2 "suspected infection group" was defined as having apparent SARS-CoV-2 symptoms without an RNA or antigen test, while the "uninfected group" was defined as having a negative SARS-CoV-2 RNA or antigen test and no SARS-CoV-2 symptoms. RESULTS: A total of 1330 patients participated in the study, 687 of whom were in the SARS-CoV-2 diagnosed group, 219 in the suspected infection group, and 424 in the uninfected group. There was no significant difference in basic characteristics among the three groups. The clinical pregnancy rate was 68% in the SARS-CoV-2 diagnosed group, 63% in the uninfected group, and 51% in the suspected infection group (P < 0.001). The ongoing pregnancy rate was 58% in the SARS-CoV-2 diagnosed group, 53% in the uninfected group, and 45% in the suspected infection group (P < 0.001). Upon analyzing the factors influencing clinical pregnancy, it was found that suspected infection (odds ratio [OR] 0.618, 95% CI 0.444-0.862, P = 0.005) and the short time (≤ 22 days) between embryo transfer and SARS-CoV-2 infection (OR 3.76, 95% CI 1.92-8.24, P < 0.001) were not conducive to clinical pregnancy. In addition, the concurrent presence of fever and dizziness/headache SARS-CoV-2 symptoms (OR 0.715, 95% CI 0.526-0.972, P = 0.032) decreased the clinical pregnancy rate. However, vaccination administered 2-3 times (OR 1.804, 95% CI 1.332-2.444, P < 0.001) was associated with an improvement in clinical pregnancy rate. CONCLUSIONS: This prospective cohort study shows that SARS-CoV-2 infection in a short period of time after embryo transfer is not conducive to clinical pregnancy. Reproductive physicians should advise patients to avoid SARS-CoV-2 infection shortly after embryo transfer. Meanwhile, women should be encouraged to vaccinate at least 2-3 times before embryo transfer or pregnancy.

Deleterious variants in X-linked RHOXF1 cause male infertility with oligo- and azoospermia.

Oligozoospermia and azoospermia are two common phenotypes of male infertility characterized by massive sperm defects owing to failure of spermatogenesis. The deleterious impact of candidate variants with male infertility is to be explored. In our study, we identified three hemizygous missense variants (c.388G>A: p.V130M, c.272C>T: p.A91V, and c.467C>T: p.A156V) and one hemizygous nonsense variant (c.478C>T: p.R160X) in the Rhox homeobox family member 1 gene (RHOXF1) in four unrelated cases from a cohort of 1201 infertile Chinese men with oligo- and azoospermia using whole-exome sequencing and Sanger sequencing. RHOXF1 was absent in the testicular biopsy of one patient (c.388G>A: p.V130M) whose histological analysis showed a phenotype of Sertoli cell-only syndrome. In vitro experiments indicated that RHOXF1 mutations significantly reduced the content of RHOXF1 protein in HEK293T cells. Specifically, the p.V130M, p.A156V, and p.R160X mutants of RHOXF1 also led to increased RHOXF1 accumulation in cytoplasmic particles. Luciferase assays revealed that p.V130M and p.R160X mutants may disrupt downstream spermatogenesis by perturbing the regulation of doublesex and mab-3 related transcription factor 1 (DMRT1) promoter activity. Furthermore, ICSI treatment could be beneficial in the context of oligozoospermia caused by RHOXF1 mutations. In conclusion, our findings collectively identified mutated RHOXF1 to be a disease-causing X-linked gene in human oligo- and azoospermia.

Human umbilical cord-derived mesenchymal stem cell transplantation improves the long COVID.

No effective treatments can ameliorate symptoms of long COVID patients. Our study assessed the safety and efficacy of human umbilical cord-derived mesenchymal stem cells (UC-MSCs) in the treatment of long COVID patients. Ten long COVID patients were enrolled and received intravenous infusions of UC-MSCs on Days 0, 7, and 14. Adverse events and clinical symptoms were recorded, and chest-high-resolution CT (HRCT) images and laboratory parameters were analyzed. During UC-MSCs treatment and follow-up, we did not observe serious adverse events, the symptoms of long COVID patients were significantly relieved in a short time, especially sleep difficulty, depression or anxiety, memory issues, and so forth, and the lung lesions were also repaired. The routine laboratory parameters did not exhibit any significant abnormalities following UC-MSCs transplantation (UMSCT). The proportion of regulatory T cells gradually increased, but it was not statistically significant until 12 months. The proportion of naive B cells was elevated, while memory B cells, class-switched B-cells, and nonswitched B-cells decreased at 1 month after infusion. Additionally, we observed a transient elevation in circulating interleukin (IL)-6 after UMSCT, while tumor necrosis factor (TNF)-α, IL-17A, and IL-10 showed no significant changes. The levels of circulating immunoglobulin (Ig) M increased significantly at month 2, while IgA increased significantly at month 6. Furthermore, the SARS-CoV-2 IgG levels remained consistently high in all patients at Month 6, and there was no significant decrease during the subsequent 12-month follow-up. UMSCT was safe and tolerable in long COVID patients. It showed potential in alleviating long COVID symptoms and improving interstitial lung lesions.

A hemizygous loss-of-function variant in BCORL1 is associated with male infertility and oligoasthenoteratozoospermia.

Oligoasthenoteratozoospermia (OAT) is a common type of male infertility; however, its genetic causes remain largely unknown. Some of the genetic determinants of OAT are gene defects affecting spermatogenesis. BCORL1 (BCL6 corepressor like 1) is a transcriptional corepressor that exhibits the OAT phenotype in a knockout mouse model. A hemizygous missense variant of BCORL1 (c.2615T > G:p.Val872Gly) was reported in an infertile male patient with non-obstructive azoospermia (NOA). Nevertheless, the correlation between BCORL1 variants and OAT in humans remains unknown. In this study, we used whole-exome sequencing to identify a novel hemizygous nonsense variant of BCORL1 (c.1564G > T:p.Glu522*) in a male patient with OAT from a Han Chinese family. Functional analysis showed that the variant produced a truncated protein with altered cellular localization and a dysfunctional interaction with SKP1 (S-phase kinase-associated protein 1). Further population screening identified four BCORL1 missense variants in subjects with both OAT (1 of 325, 0.31%) and NOA (4 of 355, 1.13%), but no pathogenic BCORL1 variants among 362 fertile subjects. In conclusion, our findings indicate that BCORL1 is a potential candidate gene in the pathogenesis of OAT and NOA, expanded its disease spectrum and suggested that BCORL1 may play a role in spermatogenesis by interacting with SKP1.

A case report of a normal fertile woman with 46,XX/46,XY somatic chimerism reveals a critical role for germ cells in sex determination.

Individuals with 46,XX/XY chimerism can display a wide range of characteristics, varying from hermaphroditism to complete male or female, and can display sex chromosome chimerism in multiple tissues, including the gonads. The gonadal tissues of females contain both granulosa and germ cells. However, the specific sex chromosome composition of the granulosa and germ cells in 46,XX/XY chimeric female is currently unknown. Here, we reported a 30-year-old woman with secondary infertility who displayed a 46,XX/46,XY chimerism in the peripheral blood. FISH testing revealed varying degrees of XX/XY chimerism in multiple tissues of the female patient. Subsequently, the patient underwent preimplantation genetic testing (PGT) treatment, and 26 oocytes were retrieved. From the twenty-four biopsied mature oocytes, a total of 23 first polar bodies (PBs) and 10 second PBs were obtained. These PBs and two immature metaphase I (MI) oocytes only displayed X chromosome signals with no presence of the Y, suggesting that all oocytes in this chimeric female were of XX germ cell origin. On the other hand, granulosa cells obtained from individual follicles exhibited varied proportions of XX/XY cell types, and six follicles possessed 100% XX or XY granulosa cells. A total of 24 oocytes were successfully fertilized, and 12 developed into blastocysts, where 5 being XY and 5 were XX. Two blastocysts were transferred with one originating from an oocyte aspirated from a follicle containing 100% XY granulosa cells. This resulted in a twin pregnancy. Subsequent prenatal diagnosis confirmed normal male and female karyotypes. Ultimately, healthy boy-girl twins were delivered at full term. In summary, this 46,XX/XY chimerism with XX germ cells presented complete female, suggesting that germ cells may exert a significant influence on the sexual determination of an individual, which provide valuable insights into the intricate processes associated with sexual development and reproduction.

Biallelic CFAP61 variants cause male infertility in humans and mice with severe oligoasthenoteratozoospermia.

BACKGROUND: The genetic causes for most male infertility due to severe oligoasthenoteratozoospermia (OAT) remain unclear. OBJECTIVE: To identify the genetic cause of male infertility characterised by OAT. METHODS: Variant screening was performed by whole-exome sequencing from 325 infertile patients with OAT and 392 fertile individuals. In silico and in vitro analyses were performed to evaluate the impacts of candidate disease-causing variants. A knockout mouse model was generated to confirm the candidate disease-causing gene, and intracytoplasmic sperm injection (ICSI) was used to evaluate the efficiency of clinical treatment. RESULTS: We identified biallelic CFAP61 variants (NM_015585.4: c.1654C>T (p.R552C) and c.2911G>A (p.D971N), c.144-2A>G and c.1666G>A (p.G556R)) in two (0.62%) of the 325 OAT-affected men. In silico bioinformatics analysis predicted that all four variants were deleterious, and in vitro functional analysis confirmed the deleterious effects of the mutants. Notably, H&E staining and electron microscopy analyses of the spermatozoa revealed multiple morphological abnormalities of sperm flagella, the absence of central pair microtubules and mitochondrial sheath malformation in sperm flagella from man with CFAP61 variants. Further immunofluorescence assays revealed markedly reduced CFAP61 staining in the sperm flagella. In addition, Cfap61-deficient mice showed the OAT phenotype, suggesting that loss of function of CFAP61 was the cause of OAT. Two individuals accepted ICSI therapy using their own ejaculated sperm, and one of them succeeded in fathering a healthy baby. CONCLUSIONS: Our findings indicate that CFAP61 is essential for spermatogenesis and that biallelic CFAP61 variants lead to male infertility in humans and mice with OAT.

Homozygous ACTL9 mutations cause irregular mitochondrial sheath arrangement and abnormal flagellum assembly in spermatozoa and male infertility.

PURPOSE: To identify novel variants in ACTL9 and new phenotypes responsible for male infertility. METHODS: Genomic DNA was extracted from peripheral blood samples for whole-exome sequencing (WES). Computer-assisted sperm analysis (CASA) was used to test the motility of spermatozoa. The ultrastructure of flagella and the mitochondrial sheath were assessed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Immunostaining was used to validate the localization and expression of ACTL9 and ACTL7A. An Actl9-mutated mouse model was used to validate the phenotypes by CASA and TEM. RESULTS: We identified novel homozygous variants in ACTL9 in two independent Chinese families. Spermatozoa with ACTL9 mutations showed decreased CASA parameters and a higher proportion of spermatozoa with abnormal morphology, exhibiting coiled flagella and a thickened midpiece. The spermatozoa were characterized by chaotic or irregular '9+2' structures and irregular mitochondrial sheath arrangements in the flagellum. Actl9 knock-in mice also showed abnormal CASA parameters and irregular '9+2' structures in flagella. CONCLUSIONS: Our study expands the mutation spectrum and phenotypic spectrum of ACTL9.

Extended application of PGT-M strategies for small pathogenic CNVs.

PURPOSE: The preimplantation genetic testing for aneuploidy (PGT-A) platform is not currently available for small copy-number variants (CNVs), especially those < 1 Mb. Through strategies used in PGT for monogenic disease (PGT-M), this study intended to perform PGT for families with small pathogenic CNVs. METHODS: Couples who carried small pathogenic CNVs and underwent PGT at the Reproductive and Genetic Hospital of CITIC-Xiangya (Hunan, China) between November 2019 and April 2023 were included in this study. Haplotype analysis was performed through two platforms (targeted sequencing and whole-genome arrays) to identify the unaffected embryos, which were subjected to transplantation. Prenatal diagnosis using amniotic fluid was performed during 18-20 weeks of pregnancy. RESULTS: PGT was successfully performed for 20 small CNVs (15 microdeletions and 5 microduplications) in 20 families. These CNVs distributed on chromosomes 1, 2, 6, 7, 13, 15, 16, and X with sizes ranging from 57 to 2120 kb. Three haplotyping-based PGT-M strategies were applied. A total of 89 embryos were identified in 25 PGT cycles for the 20 families. The diagnostic yield was 98.9% (88/89). Nineteen transfers were performed for 17 women, resulting in a 78.9% (15/19) clinical pregnancy rate after each transplantation. Of the nine women who had healthy babies, eight accepted prenatal diagnosis and the results showed no related pathogenic CNVs. CONCLUSION: Our results show that the extended haplotyping-based PGT-M strategy application for small pathogenic CNVs compensated for the insufficient resolution of PGT-A. These three PGT-M strategies could be applied to couples with small pathogenic CNVs.

[Genetic analysis and assisted reproductive guidance for two infertile patients with rare small supernumerary marker chromosomes].

OBJECTIVE: To carry out cytogenetic and molecular genetic analysis for two infertile patients carrying rare small supernumerary marker chromosomes (sSMC). METHODS: Two infertile patients who received reproductive and genetic counseling at CITIC Xiangya Reproductive and Genetic Hospital on October 31, 2018 and May 10, 2021, respectively were selected as the study subjects. The origin of sSMCs was determined by conventional G banding, fluorescence in situ hybridization (FISH) and copy number variation sequencing (CNV-seq). Microdissection combined with high-throughput whole genome sequencing (MicroSeq) was carried out to determine the fragment size and genomic information of their sSMCs. RESULTS: For patient 1, G-banded karyotyping and FISH revealed that he has a karyotype of mos47,XY,del(16)(p10p12),+mar[65]/46,XY,del(16)(p10p12)[6]/48,XY,del(16)(p10p12),+2mar[3].ish mar(Tel 16p-,Tel 16q-,CEP 16-,WCP 16+). CNV analysis has yielded a result of arr[GRCh37]16p12.1p11.2(24999364_33597595)×1[0.25]. MicroSeq revealed that his sSMC has contained the region of chromosome 16 between 24979733 and 34023115 (GRCh37). For patient 2, karyotyping and reverse FISH revealed that she has a karyotype of mos 47,XX,+mar[37]/46,XX[23].rev ish CEN5, and CNV analysis has yielded a result of seq[GRCh37]dup(5)(p12q11.2)chr5:g(45120001_56000000)dup[0.8]. MicroSeq results revealed that her sSMC has contained the region of chromosome 5 between 45132364 and 55967870(GRCh37). After genetic counseling, both couples had opted in vitro fertilization (IVF) treatment and preimplantation genetic testing (PGT). CONCLUSION: For individuals harboring sSMCs, it is vital to delineate the origin and structural characteristics of the sSMCs for their genetic counseling and reproductive guidance. Preimplantation genetic testing after microdissection combined with high-throughput whole genome sequencing (MicroSeq-PGT) can provide an alternative treatment for carrier couples with a high genetic risk.

Loss-of-function missense variant of AKAP4 induced male infertility through reduced interaction with QRICH2 during sperm flagella development.

Sperm fibrous sheath (FS) is closely related to sperm maturation, capacitation and motility, and A-kinase anchor protein 4 (AKAP4) is the most abundant protein in sperm FS. Previous studies found incomplete sperm FSs and abnormal flagella in Akap4 knockout mice. Meanwhile, it was reported that the partial deletion in AKAP4 is highly relevant to the dysplasia of the FS in an infertile man, and so far, there is no report about male infertility caused by hemizygous AKAP4 variant. Furthermore, the specific mechanisms of how the variant is relevant to the phenotype remain elusive. In this study, we investigated three multiple morphological abnormalities of the sperm flagella-affected men from three independent families (including one consanguine family) carried hemizygous c.C1285T variant in AKAP4. The patients carried this variant, which showed dysplastic sperm FS, and the protein expression of AKAP4 was decreased in flagella, which was further confirmed in HEK-293T cells in vitro. In addition, the co-localization and interaction between AKAP4 and glutamine-rich protein 2 (QRICH2) on the molecular level were identified by immunofluorescence and co-immunoprecipitation (CO-IP). The hemizygous c.1285C > T variant in AKAP4 induced decreased protein expression of QRICH2 in spermatozoa. These results suggested that the normal expression of AKAP4 is required for maintaining the expression of QRICH2 and the decreased protein expression of AKAP4 and QRICH2，as well as the interaction between them induced by the hemizygous variant of AKAP4 caused dysplastic fibrous sheath, which eventually led to reduced sperm motility and male infertility.

CFAP65 is required in the acrosome biogenesis and mitochondrial sheath assembly during spermiogenesis.

Asthenoteratospermia is a common cause of male infertility. Recent studies have revealed that CFAP65 mutations lead to severe asthenoteratospermia due to acrosome hypoplasia and flagellum malformations. However, the molecular mechanism underlying CFAP65-associated sperm malformation is largely unclear. Here, we initially examined the role of CFAP65 during spermiogenesis using Cfap65 knockout (Cfap65-/-) mice. The results showed that Cfap65-/- male mice exhibited severe asthenoteratospermia characterized by morphologically defective sperm heads and flagella. In Cfap65-/- mouse testes, hyper-constricted sperm heads were apparent in step 9 spermatids accompanied by abnormal manchette development, and acrosome biogenesis was abnormal in the maturation phase. Moreover, subsequent flagellar elongation was also severely affected and characterized by disrupted assembly of the mitochondrial sheath (MS) in Cfap65-/- male mice. Furthermore, the proteomic analysis revealed that the proteostatic system during acrosome formation, manchette organization and MS assembly was disrupted when CFAP65 was lost. Importantly, endogenous immunoprecipitation and immunostaining experiments revealed that CFAP65 may form a cytoplasmic protein network comprising MNS1, RSPH1, TPPP2, ZPBP1 and SPACA1. Overall, these findings provide insights into the complex molecular mechanisms of spermiogenesis by uncovering the essential roles of CFAP65 during sperm head shaping, acrosome biogenesis and MS assembly.

Homozygous Mutations in BTG4 Cause Zygotic Cleavage Failure and Female Infertility.

Zygotic cleavage failure (ZCF) is a unique early embryonic phenotype resulting in female infertility and recurrent failure of in vitro fertilization (IVF) and/or intracytoplasmic sperm injection (ICSI). With this phenotype, morphologically normal oocytes can be retrieved and successfully fertilized, but they fail to undergo cleavage. Until now, whether this phenotype has a Mendelian inheritance pattern and which underlying genetic factors play a role in its development remained to be elucidated. B cell translocation gene 4 (BTG4) is a key adaptor of the CCR4-NOT deadenylase complex, which is involved in maternal mRNA decay in mice, but no human diseases caused by mutations in BTG4 have previously been reported. Here, we identified four homozygous mutations in BTG4 (GenBank: NM_017589.4) that are responsible for the phenotype of ZCF, and we found they followed a recessive inheritance pattern. Three of them-c.73C>T (p.Gln25Ter), c.1A>G (p.?), and c.475_478del (p.Ile159LeufsTer15)-resulted in complete loss of full-length BTG4 protein. For c.166G>A (p.Ala56Thr), although the protein level and distribution of mutant BTG4 was not altered in zygotes from affected individuals or in HeLa cells, the interaction between BTG4 and CNOT7 was abolished. In vivo studies further demonstrated that the process of maternal mRNA decay was disrupted in the zygotes of the affected individuals, which provides a mechanistic explanation for the phenotype of ZCF. Thus, we provide evidence that ZCF is a Mendelian phenotype resulting from mutations in BTG4. These findings contribute to our understanding of the role of BTG4 in human early embryonic development and provide a genetic marker for female infertility.

Novel homozygous variant of CCIN causes male infertility owing to the abnormal sperm head with a nuclear subsidence phenotype.

(A) Characteristics of spermatozoa in asthenoteratozoospermia affected man. (B) Pedigree and Sanger sequencing analysis of the family. (C) The effect of the missense variant in the CCIN gene.

Biallelic variants in IQCN cause sperm flagellar assembly defects and male infertility.

STUDY QUESTION: What is the effect of defects in the manchette protein IQ motif-containing N (IQCN) on sperm flagellar assembly? SUMMARY ANSWER: Deficiency in IQCN causes sperm flagellar assembly defects and male infertility. WHAT IS KNOWN ALREADY: The manchette is a transient structure that is involved in the shaping of the human spermatid nucleus and protein transport within flagella. Our group recently reported that the manchette protein IQCN is essential for fertilization. Variants in IQCN lead to total fertilization failure and defective acrosome structure phenotypes. However, the function of IQCN in sperm flagellar assembly is still unknown. STUDY DESIGN, SIZE, DURATION: Fifty men with infertility were recruited from a university-affiliated center from January 2014 to October 2022. PARTICIPANTS/MATERIALS, SETTING, METHODS: Genomic DNA was extracted from the peripheral blood samples of all 50 individuals for whole-exome sequencing. The ultrastructure of the spermatozoa was assessed by transmission electron microscopy. Computer-assisted sperm analysis (CASA) was used to test the parameters of curvilinear velocity (VCL), straight-line velocity (VSL), and average path velocity (VAP). An Iqcn knockout (Iqcn-/-) mouse model was generated by CRISPR-Cas9 technology to evaluate sperm motility and the ultrastructure of the flagellum. Hyperactivation and sperm fertilizing ability were assessed in a mouse model. Immunoprecipitation followed by liquid chromatography-mass spectrometry was used to detect IQCN-binding proteins. Immunofluorescence was used to validate the localization of IQCN-binding proteins. MAIN RESULTS AND THE ROLE OF CHANCE: Biallelic variants in IQCN (c.3913A>T and c.3040A>G; c.2453_2454del) were identified in our cohort of infertile men. The sperm from the affected individuals showed an irregular '9 + 2' structure of the flagellum, which resulted in abnormal CASA parameters. Similar phenotypes were observed in Iqcn-/- male mice. VSL, VCL, and VAP in the sperm of Iqcn-/- male mice were significantly lower than those in Iqcn+/+ male mice. Partial peripheral doublet microtubules (DMTs) and outer dense fibers (ODFs) were absent, or a chaotic arrangement of DMTs was observed in the principal piece and end piece of the sperm flagellum. Hyperactivation and IVF ability were impaired in Iqcn-/- male mice. In addition, we investigated the causes of motility defects and identified IQCN-binding proteins including CDC42 and the intraflagellar transport protein families that regulate flagellar assembly during spermiogenesis. LIMITATIONS, REASONS FOR CAUTION: More cases are needed to demonstrate the relation between IQCN variants and phenotypes. WIDER IMPLICATIONS OF THE FINDINGS: Our findings expand the genetic and phenotypic spectrum of IQCN variants in causing male infertility, providing a genetic marker for sperm motility deficiency and male infertility. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by the National Natural Science Foundation of China (81974230 and 82202053), the Changsha Municipal Natural Science Foundation (kq2202072), the Hunan Provincial Natural Science Foundation (2022JJ40658), and the Scientific Research Foundation of Reproductive and Genetic Hospital of CITIC-Xiangya (YNXM-202114 and YNXM-202201). No conflicts of interest were declared. TRIAL REGISTRATION NUMBER: N/A.

Biallelic variants in KCTD19 associated with male factor infertility and oligoasthenoteratozoospermia.

STUDY QUESTION: Can whole-exome sequencing (WES) reveal new genetic factors responsible for male infertility characterized by oligozoospermia? SUMMARY ANSWER: We identified biallelic missense variants in the Potassium Channel Tetramerization Domain Containing 19 gene (KCTD19) and confirmed it to be a novel pathogenic gene for male infertility. WHAT IS KNOWN ALREADY: KCTD19 is a key transcriptional regulator that plays an indispensable role in male fertility by regulating meiotic progression. Kctd19 gene-disrupted male mice exhibit infertility due to meiotic arrest. STUDY DESIGN, SIZE, DURATION: We recruited a cohort of 536 individuals with idiopathic oligozoospermia from 2014 to 2022 and focused on five infertile males from three unrelated families. Semen analysis data and ICSI outcomes were collected. WES and homozygosity mapping were performed to identify potential pathogenic variants. The pathogenicity of the identified variants was investigated in silico and in vitro. PARTICIPANTS/MATERIALS, SETTING, METHODS: Male patients diagnosed with primary infertility were recruited from the Reproductive and Genetic Hospital of CITIC-Xiangya. Genomic DNA extracted from affected individuals was used for WES and Sanger sequencing. Sperm phenotype, sperm nuclear maturity, chromosome aneuploidy, and sperm ultrastructure were assessed using hematoxylin and eosin staining and toluidine blue staining, FISH and transmission electron microscopy. The functional effects of the identified variants in HEK293T cells were investigated via western blotting and immunofluorescence. MAIN RESULTS AND THE ROLE OF CHANCE: We identified three homozygous missense variants (NM_001100915, c.G628A:p.E210K, c.C893T:p.P298L, and c.G2309A:p.G770D) in KCTD19 in five infertile males from three unrelated families. Abnormal morphology of the sperm heads with immature nuclei and/or nuclear aneuploidy were frequently observed in individuals with biallelic KCTD19 variants, and ICSI was unable to rescue these deficiencies. These variants reduced the abundance of KCTD19 due to increased ubiquitination and impaired its nuclear colocalization with its functional partner, zinc finger protein 541 (ZFP541), in HEK293T cells. LIMITATIONS, REASONS FOR CAUTION: The exact pathogenic mechanism remains unclear, and warrants further studies using knock-in mice that mimic the missense mutations found in individuals with biallelic KCTD19 variants. WIDER IMPLICATIONS OF THE FINDINGS: Our study is the first to report a likely causal relationship between KCTD19 deficiency and male infertility, confirming the critical role of KCTD19 in human reproduction. Additionally, this study provided evidence for the poor ICSI clinical outcomes in individuals with biallelic KCTD19 variants, which may guide clinical treatment strategies. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by the National Key Research and Developmental Program of China (2022YFC2702604 to Y.-Q.T.), the National Natural Science Foundation of China (81971447 and 82171608 to Y.-Q.T., 82101961 to C.T.), a key grant from the Prevention and Treatment of Birth Defects from Hunan Province (2019SK1012 to Y.-Q.T.), a Hunan Provincial Grant for Innovative Province Construction (2019SK4012), and the China Postdoctoral Science Foundation (2022M721124 to W.W.). The authors declare no conflicts of interest. TRIAL REGISTRATION NUMBER: N/A.

Histological endometrial dating: a reliable tool for personalized frozen-thawed embryo transfer in patients with repeated implantation failure in natural cycles.

OBJECTIVE: To evaluate the clinical availability and stability of histological endometrial dating as a tool for personalized frozen-thawed embryo transfer (pFET) in patients with repeated implantation failure (RIF) in natural cycles. METHODS: A total of 1245 RIF patients were recruited to the present study. All of the patients received an endometrial dating evaluation on day 7 post-ovulation (PO + 7) to guide their first pFET. The second and third pFETs were executed according to histological examination (again employing biopsy) or by reference to previous results. Subsequent pregnancy outcomes for all of the cycles were ultimately tracked. RESULTS: The out-of-phase rate for RIF patients was 32.4% (404/1245) and the expected dating rate (the probability of the expected endometrial dating aligning with repeat biopsy) for endometrial dating reevaluation was as high as 94.3% (50/53). The clinical pregnancy rates of first, second, and third pFETs were 65.3%, 50.0%, and 44.4%, respectively; and the cumulative clinical pregnancy rate attained 74.9% after three transfers. Endometrial dating reevaluations met expectations with more than a 2-year duration in three cases and elicited favorable clinical outcomes. CONCLUSION: We validated the relatively high stability of the histological endometrial dating platform-including the out-of-phase rate and the expected dating rate of reevaluation in patients with RIF-by expanding the sample size. The pFET, based on histological endometrial dating, was of acceptable clinical value and was worthy of promotion in patients with unexplained RIF.

Biallelic variants in ZFP36L2 cause female infertility characterised by recurrent preimplantation embryo arrest.

BACKGROUND: Recurrent preimplantation embryo developmental arrest (RPEA) is the most common cause of assisted reproductive technology treatment failure associated with identified genetic abnormalities. Variants in known maternal genes can only account for 20%-30% of these cases. The underlying genetic causes for the other affected individuals remain unknown. METHODS: Whole exome sequencing was performed for 100 independent infertile females that experienced RPEA. Functional characterisations of the identified candidate disease-causative variants were validated by Sanger sequencing, bioinformatics and in vitro functional analyses, and single-cell RNA sequencing of zygotes. RESULTS: Biallelic variants in ZFP36L2 were associated with RPEA and the recurrent variant (p.Ser308_Ser310del) prevented maternal mRNA decay in zygotes and HeLa cells. CONCLUSION: These findings emphasise the relevance of the relationship between maternal mRNA decay and human preimplantation embryo development and highlight a novel gene potentially responsible for RPEA, which may facilitate genetic diagnoses.