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Background: Early embryonic arrest and fragmentation (EEAF) is a common cause of female infertility, but the genetic causes remain to be largely unknown. CIP2A encodes the cellular inhibitor of PP2A, playing a crucial role in mitosis and mouse oocyte meiosis., Methods: Exome sequencing and Sanger sequencing were performed to identify candidate causative genes in patients with EEAF. The pathogenicity of the CIP2A variant was assessed and confirmed in cultured cell lines and human oocytes through Western blotting, semi-quantitative RT-PCR, TUNEL staining, and fluorescence localization analysis., Findings: We identified CIP2A (c.1510C > T, p.L504F) as a novel disease-causing gene in human EEAF from a consanguineous family. L504 is highly conserved throughout evolution. The CIP2A variant (c.1510C > T, p.L504F) reduced the expression level of the mutant CIP2A protein, leading to the abnormal aggregation of mutant CIP2A protein and cell apoptosis. Abnormal aggregation of CIP2A protein and chromosomal dispersion occurred in the patient's oocytes and early embryos. We further replicated the patient phenotype by knockdown CIP2A in human oocytes. Additionally, CIP2A deficiency resulted in decreased levels of phosphorylated ERK1/2., Interpretation: We first found that the CIP2A loss-of-function variant associate with female infertility characterized by EEAF. Our findings suggest the uniqueness and importance of CIP2A gene in human oocyte and early embryo development., Funding: This work was supported by National Key Research and Development Program of China (2023YFC2706302), the National Natural Science Foundation of China (81000079, 81170165, and 81870959), the HUST Academic Frontier Youth Team (2016QYTD02), and the Key Research of Huazhong University of Science and Technology, Tongji Hospital (2022A20)., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

ZP1 is a critical glycoprotein in the formation of the zona pellucida. It plays an indispensable role in the maturation of oocytes. To identify the causative gene of empty follicle syndrome (EFS) in a patient from a consanguineous family, whole-exome sequencing was performed in the proband. We identified a novel homozygous nonsense mutation c.1260C > G (p. Tyr420X) in the ZP1 gene from two primary infertile patients. Western blot showed that Y420X mutation in ZP1 gene produced a truncated protein. However, the mutation had no significant effect on subcellular localization of the mutant protein. Our findings confirmed the important role of the ZP1 gene in human female reproduction, enriched the mutation spectrums of ZP1 gene, and expanded its applications in the clinical and molecular diagnoses of EFS., (© 2022. Society for Reproductive Investigation.)

Zona pellucida (ZP) which is an extracellular matrix consisting of ZP1, ZP2, ZP3, and ZP4 plays a vital role in oocyte maturity, early embryonic development, and fertilization process. Any alterations of structure or function may lead to the abnormal formation of ZP and female infertility. Two novel heterozygous mutations c.1859G > A (p.Cys620Tyr) and c.1421 T > C (p.Leu474Pro) in ZP2 gene were recognized in three patients from two unrelated families with abnormal ZP and female infertility in this study. The expression constructs carrying wild-type ZP2 gene, c.1859G > A (p.Cys620Tyr) mutant ZP2 gene, and c.1421 T > C (p.Leu474Pro) mutant ZP2 gene were transfected into CHO cells respectively. There was a remarkable decrease in the expression of p.Cys620Tyr mutant protein with western blot. In addition, secretion of p.Leu474Pro mutant protein in the culture medium reduced markedly compared with that of wild-type ZP2 protein. Furthermore, co-immunoprecipitation showed that the p.Leu474Pro mutation affected the interaction between ZP2 and ZP3. Prediction of three-dimensional (3D) structure of the proteins showed that p.Cys620Tyr mutation altered the disulfide bond of ZP2 protein and may affect its function. These findings extend the ranges of mutations of ZP2 gene. Meanwhile, it will be helpful to the precise diagnosis of abnormal ZP., (© 2022. Society for Reproductive Investigation.)

Purpose: The aim of this study was to identify the disease-causing mutations found in three infertile female patients who were diagnosed with abnormal zona pellucida (ZP) and empty follicle syndrome (EFS)., Methods: We performed whole-exome sequencing and Sanger sequencing to identify and verify the disease-causing mutations. Additionally, we performed Western blotting and mini-gene splicing assay to assess the effects of the mutations., Results: We identified two novel compound heterozygous mutations in the ZP2 gene, a patient with an abnormal ZP carrying a novel compound heterozygous mutation (c.1695-2A>G and c.1831G>T, p.V611F) and a patient with EFS carrying a novel compound heterozygous mutation (c.1695-2A>G and c.1924 C>T, p.R642*). Furthermore, we identified a patient with typical abnormal ZP carrying a novel heterozygous mutation (c.400G>T, p.A134S) in the ZP3 gene. The splice site mutation (c.1695-2A>G) can cause abnormal pre-mRNA splicing that inserts an extra sequence of 61 bp in the mRNA of ZP2, and the missense mutation (c.1831G>T) can cause a decrease of ZP2 protein in HEK293 cells., Conclusion: We identified three novel mutations in the ZP2 gene and the ZP3 gene in three Chinese female patients with infertility. Our study expands the spectrum of ZP gene mutations and phenotypes and thus is beneficial in the genetic diagnosis of infertility in females., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Tubulin beta 8 class VIII (TUBB8) is a special β-tubulin isotype that mainly expressed in primate oocytes and early embryos and identified as the disease-causing gene of human oocyte maturation arrest. To identify the disease-causing genes in 2 patients with female infertility due to large polar body oocyte or fertilization failure, whole-exome sequencing was performed on the patients and available family members. We identified a novel heterozygous missense mutation c.817C>G (p.L273V) and a recently reported heterozygous missense mutation c.608A>G (p.D203G) in TUBB8 from two patients, respectively. We found oocyte with a large polar body in the patient who carried the p.D203G mutation in TUBB8. Bioinformatics analysis showed that these two mutations are harmful. The results of western blot and RT-PCR experiments showed that the D203G mutation caused a significant decrease in the expression of TUBB8, and immunostaining showed that the TUBB8 mutation caused abnormal microtubule morphology. These findings suggest that TUBB8 mutations resulted in oocyte with a large polar body and fertilization failure in patients., (© 2021. Society for Reproductive Investigation.)

Purpose: To identify disease-causing genes involved in female infertility., Methods: Whole-exome sequencing and Sanger DNA sequencing were used to identify the mutations in disease-causing genes. We performed subcellular protein localization, western immunoblotting analysis, and co-immunoprecipitation analysis to evaluate the effects of the mutation., Results: We investigated 17 families with female infertility. Whole-exome and Sanger DNA sequencing were used to characterize the disease gene in the patients, and we identified a novel heterozygous mutation (p.Ser173Cys, c.518C > G) in the ZP3 gene in a patient with empty follicle syndrome. When we performed co-immunoprecipitation analysis, we found that the S173C mutation affected interactions between ZP3 and ZP2., Conclusions: We identified a novel mutation in the ZP3 gene in a Chinese family with female infertility. Our findings thus expand the mutational and phenotypical spectrum of the ZP3 gene, and they will be helpful in precisely diagnosing this aspect of female infertility.

Purpose: Mutations in the zona pellucida glycoprotein genes have been reported to be associated with empty follicle syndrome (EFS) and abnormal zona pellucida (ZP). In this study, we performed genetic analysis in the patients with female infertility due to abnormal zona pellucida and empty follicle syndrome to identify the disease-causing gene mutations in these patients., Methods: We characterized three patients from two independent families who had suffered from empty follicle syndrome or abnormal zona pellucida. Whole exome sequencing and Sanger sequencing were used to identify the mutations in the families. Western blot was used to check the expression of wild type and mutant disease genes., Results: We identified two novel mutations in these patients, including a novel compound heterozygous mutation (c.507delC, p. His170fs; c.239 G>A, p. Cys80Tyr and c.241 T>C, p. Tyr81His) in ZP1 gene and a compound mutation in ZP2 gene (c.860_861delTG, p.Val287fs and c.1924 C>T, p.Arg642Ter). Expression of the mutant ZP1 protein (p. Cys80Tyr and p. Tyr81His) is significantly decreased compared with the wild-type ZP1. Other three mutations produce truncated proteins., Conclusions: Our findings expand the mutational spectrum of ZP1 and ZP2 genes associated with EFS and abnormal oocytes and provide new support for the genetic diagnosis of female infertility.

Purpose: To identify the disease gene in 40 patients with female infertility due to oocyte maturation arrest., Methods: Genomic DNA was extracted from peripheral blood of 40 patients and their family members. Whole-exome sequencing was performed on the patients, and the PATL2 mutations were identified and confirmed by Sanger sequencing. Harmfulness of the mutations was analyzed by SIFT, Polyphen-2, Mutation Taster, and M-CAP software, and we used western immunoblotting analysis to check the effect of mutations on PATL2 protein expression in vitro., Results: Two novel missense mutations c.1528C>A (p.Pro510Thr) and c.1376C>A (p.Ser459Tyr) in PATL2 were identified in three patients (7.5%) from two consanguineous families in our cohort. We found that mutations in PATL2 resulted in variable oocyte phenotypes, including GV arrest, MI arrest, and morphologic abnormalities. Western immunoblotting analysis showed that the expression levels of the two novel mutant PATL2 proteins decreased significantly., Conclusions: We identified two novel PATL2 mutations that caused oocyte maturation arrest and abnormal morphology, and variable phenotypes in patients.

Purpose: To identify the disease-causing gene in a family with female infertility and fertilization failure., Methods: Whole-exome sequencing and Sanger sequencing were used to identify the disease-causing gene in a female with infertility and fertilization failure. Subcellular localization and western blot analysis were used to check the effect of mutations., Results: We identified novel compound heterozygous mutations c.598C>T (p.Arg200Ter) and c.1319G>C (p.Trp440Ser) in WEE2 gene in a female with infertility and fertilization failure. The p.Arg200Ter mutant WEE2 gene produce truncated protein and mainly located in the nucleus, the same as the wild protein, while the p.Trp440Ser mutant WEE2 proteins are located in the nucleus and cytoplasm and the expression level of p.Trp440Ser mutant WEE2 protein is reduced significantly compared with that of wild-type WEE2., Conclusions: We discovered novel compound heterozygous mutations c.598C>T (p.Arg200Ter) and c.1319G>C (p.Trp440Ser) in WEE2 gene in a female whose oocytes could not form pronucleus after intracytoplasmic sperm injection (ICSI). Moreover, mutations in WEE2 gene affect the normal function of WEE2 proteins and cause fertilization failure.