Borderline form of empty follicle syndrome treated with a novel dual trigger method combined with delayed oocyte retrieval: A case report

Does dual trigger improve euploidy rate in normoresponder? A cross-sectional study

Background

With the introduction of the dual triggering-gonadotropin-releasing hormone (GnRH) analog and recombinant human chorionic gonadotropin (hCG) combination, women with a history of low mature oocyte proportion and empty follicle syndrome were shown to benefit from the dual trigger.

Objective

To investigate whether dual triggering of oocyte maturation with a GnRH agonist (GnRHa) combined with hCG can affect the euploidy rate and improve in vitro fertilization outcomes for normoresponder women.

Materials and Methods

In this cross-sectional study, 494 women who underwent controlled ovarian stimulation with hCG (n = 274) or dual triggering (hCG+GnRHa, n = 220) at Acibadem Maslak hospital, Assisted Reproductive Unit, from January 2019-2022 were enrolled in this study. Preimplantation genetic testing for aneuploidy was performed on all participants.

Results

Both groups had similar baseline and clinical characteristics. Of the 881 embryos biopsied, 312 (35.4%) were reported as euploid in the hCG trigger group; in the dual trigger group, 186 (29.8%) of 623 screening embryos were reported as euploid. The hCG group had a higher euploidy rate per biopsied embryo, although the difference was not statistically significant (31.4 ± 26.5 vs. 26.5 ± 33.3, p > 0.05).

Conclusion

In normoresponders, adding GnRHa for final follicular maturation to hCG did not improve the euploidy rate.

Can successful pregnancy be achieved and predicted from patients with identified ZP mutations? A literature review

BACKGROUND

In mammals, normal fertilization depends on the structural and functional integrity of the zona pellucida (ZP), which is an extracellular matrix surrounding oocytes. Mutations in ZP may affect oogenesis, fertilization and early embryonic development, which may cause female infertility.

METHODS

A PubMed literature search using the keywords 'zona pellucida', 'mutation' and 'variant' limited to humans was performed, with the last research on June 30, 2022. The mutation types, clinical phenotypes and pregnancy outcomes were summarized and analyzed. The naive Bayes classifier was used to predict clinical pregnancy outcomes for patients with ZP mutations.

RESULTS

A total of 29 publications were included in the final analysis. Sixty-nine mutations of the ZP genes were reported in 87 patients with different clinical phenotypes, including empty follicle syndrome (EFS), ZP-free oocytes (ZFO), ZP-thin oocytes (ZTO), degenerated and immature oocytes. The phenotypes of patients were influenced by the types and location of the mutations. The most common effects of ZP mutations are protein truncation and dysfunction. Three patients with ZP1 mutations, two with ZP2 mutations, and three with ZP4 mutations had successful pregnancies through Intracytoplasmic sperm injection (ICSI) from ZFO or ZTO. A prediction model of pregnancy outcome in patients with ZP mutation was constructed to assess the chance of pregnancy with the area under the curve (AUC) of 0.898. The normalized confusion matrix showed the true positive rate was 1.00 and the true negative rate was 0.38.

CONCLUSION

Phenotypes in patients with ZP mutations might be associated with mutation sites or the degree of protein dysfunction. Successful pregnancy outcomes could be achieved in some patients with identified ZP mutations. Clinical pregnancy prediction model based on ZP mutations and clinical characteristics will be helpful to precisely evaluate pregnancy chance and provide references and guidance for the clinical treatment of relevant patients.

A novel homozygous nonsense mutation in zona pellucida 1 (ZP1) causes human female empty follicle syndrome

PURPOSE

To identify a pathogenic gene mutation in a female infertility proband characterized by empty follicle syndrome (EFS) and explore the genetic cause of EFS.

METHODS

Whole exome sequencing (WES) was performed to identify the candidate pathogenic mutation. Sanger sequencing was used to validate the mutation in family members. The pathogenicity of the identified variant and its possible effects on the protein were evaluated with in silico tools. Immunofluorescence staining was used to study the possible mechanism of the mutation on affected oocyte.

RESULTS

We identified a family with a novel homozygous nonsense mutation in zona pellucida 1 (ZP1) (c.199G > T [p.Glu67Ter]). Based on bioinformatics analysis, the mutation was predicted to be pathogenic. This variant generates a premature stop codon in exon 2 at the 199th nucleotide, and was inferred to result in a truncated ZP1 protein of 67 amino acids at the ZP-N1 domain. An in vitro study showed that the oocyte of the EFS proband was degenerated and the zona pellucida was absent. Additionally, the mutant ZP1 proteins were localized in the cytoplasm of the degenerated oocyte but not at the surface.

CONCLUSIONS

The novel mutation in ZP1 is a genetic cause of female infertility characterized by EFS. Our finding expands the genetic spectrum for EFS and will help justify the EFS diagnosis in patients.