Objective: To investigate the characteristics and outcomes of low prognosis patients defined by POSEIDON criteria undergoing IVF treatment. Design: Retrospective cohort analysis. Setting: An IVF clinic in a public hospital. Patients: 18,455 fresh aspirated IVF cycles with subsequently frozen embryo transfer from Jan 2014 to Jan 2017 in a single IVF clinic were included in the analysis. The low prognosis patients were categorized into 4 groups based on POSEIDON criteria: group 1: age < 35, antral follicle count (AFC) ≥ 5, number of oocytes retrieved ≤ 9 in the previous cycle; group 2: age ≥ 35, AFC≥5, number of oocytes retrieved ≤ 9 in the previous cycle; group 3: age < 35, AFC < 5; group 4: age ≥ 35, AFC < 5. The non-low prognosis patients: group 5: AFC ≥ 5, previous number of oocytes retrieved > 9 oocytes; group 6: AFC ≥ 5, no previous ovarian stimulation. Intervention(s): None. Main Outcome Measure: The primary outcome was cumulative live birth rate (CLBR). Result(s): Taking group 1 as reference, the CLBR from young women in group 3 (35.5%, OR 0.9, 95% CI 0.7–1.2) was slightly lower than that in group 1 (44.6%, p = 0.615). The CLBR in group 2 (24.5%, OR 0.6, 95% CI 0.4–0.8, p = 0.004) and group 4 (12.7%, OR 0.4, 95% CI 0.3–0.6, p < 0.001) was significant lower than that in group 1. In non-poor prognosis patients, the CLBR from young women in group 5 (53.5% OR 1.3 95% CI 0.9, 1.7, p = 0.111) was a slight higher than the reference group 1 while the highest CLBR was originated from the first IVF patients with good ovarian reserve in group 6 (66.9%, OR 2.0, 95% CI 1.6, 2.4). Conclusion(s): The CLBRs and implantation rates in the young women (group 3) with diminished ovarian reserve was similar in those young women (group 1), and was significantly higher than in advanced age women with a fair ovarian reserve (group 2). Though patients in group 2 had better ovarian reserve, more oocytes and more embryos, the pregnancy outcome was inferior to that of group 3 patients with poorer ovarian reserve, fewer oocytes and fewer embryos.

Can any new genetic factors responsible for early embryonic arrest in infertile patients be identified, together with the mechanism of pathogenic variants? We identified three homozygous variants in the F-box protein 43 gene (FBXO43) in infertile patients and studies on the effects of the variants in HEK293T cells and mouse oocytes provided evidence for a causal relation between FBXO43 and female infertility. FBXO43, an inhibitor of the anaphase-promoting complex/cyclosome, mediates Metaphase II arrest as a component of the cytostatic factor in oocytes. Both male and female Fbxo43 knockout mice are viable but sterile. FBXO43, therefore, appears to be an essential component of the mammalian cell-cycle machinery that regulates both male and female meiosis. Until now, only one article has reported a homozygous FBXO43 variant associated with teratozoospermia, but the causal relationship was not established with functional evidence. Whole-exome sequencing (WES) and homozygosity mapping were performed in 24 probands from consanguineous families who suffered from early embryonic arrest, and two different homozygous variants in FBXO43 were identified in two independent families. WES data from a further 950 infertile women with early embryonic arrest were screened for homozygous and compound heterozygous variants in FBXO43, and a third individual with an additional homozygous variant in FBXO43 was identified. The infertile patients presenting with early embryonic arrest were recruited from August 2016 to May 2020. The women diagnosed with primary infertility were recruited from the reproduction centers of local hospitals. Genomic DNA samples from the affected individuals, their family members, and healthy controls were extracted from peripheral blood. The FBXO43 variants were identified using WES, homozygosity mapping, in silico analysis, and variant screening. All of the variants were confirmed by Sanger sequencing, and the effects of the variants were investigated in human embryonic kidney (HEK) 293T cells by western blotting and in mouse oocytes by complementary RNA injection. We identified three homozygous variants in FBXO43 (NM_001029860.4)—namely, c.1490_1497dup (p.(Glu500Serfs*2)), c.1747C>T (p.(Gln583*)), and c.154delG (p.(Asp52Thrfs*30))—in three independent families. All of the homozygous variants reduced the protein level of FBXO43 and reduced the level of its downstream target Cyclin B1 in HEK293T cells. In addition, the variants reduced the ability of exogenous human FBXO43 to rescue the parthenogenetic activation phenotype in Fbxo43 knockdown mouse oocytes. Owing to the lack of in vivo data from the oocytes of patients, the exact molecular mechanism remains unknown and should be further investigated using knock out or knock in mice. Our study has identified three pathogenic variants in FBXO43 that are involved in human early embryonic arrest. These findings contribute to our understanding of the role of FBXO43 in human early embryonic development and provide a new genetic marker for female infertility. This work was supported by the National Key Research and Development Program of China (2018YFC1003800, 2017YFC1001500, and 2016YFC1000600), the National Natural Science Foundation of China (81725006, 81822019, 81771581, 81971450, 81971382, and 82001552), the project supported by the Shanghai Municipal Science and Technology Major Project (2017SHZDZX01), the Project of the Shanghai Municipal Science and Technology Commission (19JC1411001), the Natural Science Foundation of Shanghai (19ZR1444500), the Shuguang Program of the Shanghai Education Development Foundation and the Shanghai Municipal Education Commission (18SG03), the Foundation of the Shanghai Health and Family Planning Commission (20154Y0162), the Capacity Building Planning Program for Shanghai Women and Children’s Health Service, and the collaborative innovation center project construction for Shanghai Women and Children’s Health. None of the authors have any competing interests. N/A

Spindle bipolarization, the process of a microtubule mass transforming into a bipolar spindle, is a prerequisite for accurate chromosome segregation. In contrast to mitotic cells, the process and mechanism of spindle bipolarization in human oocytes remains unclear. Using high-resolution imaging in more than 1800 human oocytes, we revealed a typical state of multipolar intermediates that form during spindle bipolarization and elucidated the mechanism underlying this process. We found that the minor poles formed in multiple kinetochore clusters contribute to the generation of multipolar intermediates. We further determined the essential roles of HAUS6, KIF11, and KIF18A in spindle bipolarization and identified mutations in these genes in infertile patients characterized by oocyte or embryo defects. These results provide insights into the physiological and pathological mechanisms of spindle bipolarization in human oocytes.

Spermatozoon represents a very special cell type in human body, and glycosylation plays essential roles in its whole life including spermatogenesis, maturation, capacitation, sperm–egg recognition, and fertilization. In this study, by mapping the most comprehensive N-glycoproteome of human spermatozoa using our recently developed site-specific glycoproteomic approaches, we show that spermatozoa contain a number of distinctive glycoproteins, which are mainly involved in spermatogenesis, acrosome reaction and sperm:oocyte membrane binding, and fertilization. Heavy fucosylation is observed on 14 glycoproteins mostly located at extracellular and cell surface regions in spermatozoa but not in other tissues. Sialylation and Lewis epitopes are enriched in the biological process of immune response in spermatozoa, while bisected core structures and LacdiNAc structures are highly expressed in acrosome. These data deepen our knowledge about glycosylation in spermatozoa and lay the foundation for functional study of glycosylation and glycan structures in male infertility.