Genetic evidence of ‘genuine’ empty follicle syndrome: a novel effective mutation in the LHCGR gene and review of the literature

Exome sequencing in genuine empty follicle syndrome: Novel candidate genes

OBJECTIVE(S)

Empty follicle syndrome (EFS) is a condition in which no oocytes are retrieved in an IVF cycle despite apparently normal follicular development and meticulous follicular aspiration following ovulation induction. The EFS is called genuine (gEFS) when the trigger administration is correct. The existence of gEFS is a subject of controversy, and it is quite rare with an undetermined etiology. Genetic defects in specific genes have been demonstrated to be responsible for this condition in some patients. Our objective was to identify novel genetic variants associated with gEFS.

STUDY DESIGN

We conducted a prospective observational study including 1,689 egg donors from July 2017 to February 2023. WES were performed in patients suffering gEFS.

RESULTS

Only 7 patients (0.41 %) exhibited gEFS after two ovarian stimulation cycles and we subsequently performed whole exome sequencing (WES) on these patients. Following stringent filtering, we identified 6 variants in 5 affected patients as pathogenic in new candidate genes which have not been previously associated with gEFS before, but which are involved in important biological processes related to folliculogenesis. These genetic variants included c.603_618del in HMMR, c.1025_1028del in LMNB1, c.1091-1G > A in TDG, c.607C > T in HABP2, c.100 + 2 T > C in HAPLN1 and c.3592_3593del in JAG2.

CONCLUSION

As a conclusion, we identified new candidate genes related to gEFS that expand the mutational spectrum of genes related to gEFS.This study show that WES might be an efficient tool to identify the genetic etiology of gEFS and provide further understanding of the pathogenic mechanism of gEFS.

Expanding the phenotypic spectrum of LHCGR signal peptide insertion variant: novel clinical and allelic findings causing Leydig cell hypoplasia type II

PURPOSE

Leydig cell hypoplasia (LCH) type II is a rare disease with only a few cases reported. Patients presented with hypospadias, micropenis, undescended testes, or infertility. In this study, we report a new patient with compound heterozygous variants in the LHCGR gene and LCH type II phenotype.

METHODS

Whole exome sequencing (WES) was performed followed by Sanger sequencing to confirm the detected variants in the patient and his parents.

RESULTS

A novel missense variant (p.Phe444Cys) was identified in a highly conserved site and is verified to be in trans with the signal peptide's 33-bases insertion variant.

CONCLUSION

Our research provides a more comprehensive clinical and genetic spectrum of Leydig cell hypoplasia type II. It highlighted the importance of WES in the diagnosis of this uncommon genetic disorder as well as the expansion of the genotype of LCH type II.

Case report: A novel homozygous variant in ZP3 is associated with human empty follicle syndrome

Empty follicle syndrome (EFS) is a rare condition in female infertility. It is characterized by the inability to retrieve oocytes from visibly large, normally developing follicles in the ovaries, despite ovarian stimulation. The genetic factors contributing to this syndrome remain unclear. This study focused on patients who underwent three consecutive ovarian stimulation procedures for oocyte retrieval but experienced unsuccessful outcomes, despite the presence of observable large follicles. Ultrasound examinations were conducted to assess follicular development during each procedure. In order to investigate potential genetic causes, we performed whole exome sequencing on peripheral blood samples from the patient. Interestingly, we identified that this patient carries a homozygous mutation in the ZP3 genes. Within the ZP3 gene, we identified a homozygous variant [NM_001110354.2, c.176T>A (p.L59H)] specifically located in the zona pellucida (ZP) domain. Further analysis, including bioinformatics methods and protein structure modeling, was carried out to investigate the conservation of the ZP3L59H variant across different species. This homozygous variant exhibited a high degree of conservation across various species. Importantly, the homozygous ZP3L59H variant was associated with the occurrence of empty follicle syndrome in affected female patients. The homozygous ZP3L59H variant represents a newly discovered genetic locus implicated in the development of human empty follicle syndrome. Our findings contribute to a deeper understanding of the role of zona pellucida-related genes in infertility and provide valuable insights for the genetic diagnosis of female infertility.

Whole exome sequencing identifies a novel homozygous missense mutation of LHCGR gene in primary infertile women with empty follicle syndrome

AIM

The genetic basis of empty follicle syndrome (EFS) is largely unknown, and the aim of this study was to investigate the genetic causes of EFS in primary infertile women.

METHODS

Four affected women diagnosed with anovulation were recruited, and whole exome sequencing (WES) was requested for the genetic diagnosis of the cases. One hundred healthy controls were verified by Sanger sequencing.

RESULTS

A novel homozygous variant of the LHCGR gene (NM_000233:c.1847C>A) was revealed in one affected individual by WES. Trios analysis of the mutation revealed an autosomal recessive pattern. This LHCGR variant was absent in 100 healthy controls and predicted to be highly damaging to the function of LHCGR.

CONCLUSIONS

The novel variant extends the mutational spectrum of the LHCGR gene associated with female sterility, which promotes the prognostic value of testing for LHCGR mutations in infertile women with EFS.

Post-trigger luteinizing hormone concentration to positively predict oocyte yield in the antagonist protocol and its association with genetic variants of LHCGR

BACKGROUND

The concentration of human chorionic gonadotropin (hCG)/ luteinizing hormone (LH) after triggering is generally accepted as a predictor of the normal ovarian response to the trigger, but few studies have explored the distribution model of concentration and its impact on oocyte yield. Genetic variations in LHCGR, known as a receptor for hCG and LH, also play a role in oocyte maturation and retrieval. The objective of the study was to investigate the impact of concentrations of hCG/LH after triggering on oocyte yield and its association with genetic variants of LHCGR.

METHODS

A retrospective cohort study including 372 antagonist IVF cycles, in which 205 received the recombinant hCG trigger and 167 received the gonadotropin-releasing hormone agonist (GnRH-a) trigger, was conducted. The post-trigger concentrations of hCG/LH and the LHCGR N312S (rs2293275) genotype were evaluated in patients to analyse the impact of these factors on oocyte yield.

RESULTS

The oocyte retrieval rate (ORR) increased significantly among the low-, medium- and high-hCG-concentration groups (0.91 ± 0.25, 0.99 ± 0.23 and 1.08 ± 0.19, P < 0.001) and among the low-, medium- and high-LH-concentration groups (0.80 ± 0.29, 0.95 ± 0.21 and 1.07 ± 0.19, P < 0.001). The Pearson correlation coefficient between the post-trigger hCG concentration and ORR was 0.242 (P < 0.001), and that between the LH concentration and ORR was 0.454 (P < 0.001). After adjustment for confounding factors, high post-trigger LH concentrations remained associated with the significantly higher ORRs (adjusted R2 = 0.541, P < 0.001). Patients with the AG genotype of LHCGR N312S were more likely to have low post-trigger LH concentrations (46.10 IU/L versus 60.91 IU/L, P < 0.001) and a significantly lower ORR (0.85 versus 0.96, P = 0.042) than patients with the GG genotype after the GnRH-a trigger.

CONCLUSIONS

The post-trigger LH concentration can positively predict oocyte yield in antagonist IVF cycles, and patients with the AG genotype of LHCGR rs2293275 could have a suboptimal oocyte yield using the GnRH-a trigger.

Risk factors for low oocyte retrieval in patients with polycystic ovarian syndrome undergoing in vitro fertilization

BACKGROUND

The number of oocytes retrieved does not always coincide with the number of follicles aspirated in in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) treatment. Patients with high expectation of retrieval sometimes obtain few oocytes, which may be induced by improper operation or therapeutic factors. The purpose of this study was to evaluate the distribution data of oocyte retrieval rate (ORR) and to explore the risk factors for low ORR in patients with polycystic ovary syndrome (PCOS) undergoing IVF/ICSI.

METHODS

A total of 2478 patients with PCOS undergoing IVF/ICSI were involved in this retrospective case-control study from March 2016 to October 2021. The oocyte retrieval rate was calculated as the ratio of the number of obtained oocytes to the number of follicles (≥ 12 mm) on the trigger day. Patients were divided into a low ORR and a normal ORR group with the boundary of one standard deviation from the mean value of ORR. The patient characteristics, treatment protocols, serum hormone levels, and embryonic and pregnancy outcomes were analyzed.

RESULTS

The ORR exhibited a non-normal distribution, with a median of 0.818. The incidence of complete empty follicle syndrome was 0.12% (3/2478). The proportion of patients in the low ORR group who received the progestin-primed protocol was significantly higher than that in the normal ORR group (30.30% vs. 17.69%). A logistic regression analysis showed that the serum estradiol level/follicle (≥ 12 mm) ratio (OR: 0.600 (0.545-0.661)) and progesterone level (OR: 0.783 (0.720-0.853)) on the trigger day were significant factors in the development of a low ORR, with optimal cutoff values of 172.85 pg/ml and 0.83 ng/ml, respectively, as determined by receiver operating curve. Fewer high-quality embryos (2 vs. 5) and more cycles with no available embryos (5.42% vs. 0.43%) were found in the low ORR group.

CONCLUSIONS

For patients with PCOS, low estradiol levels/follicles (≥ 12 mm) and progesterone levels on the trigger day and the use of the progestin-primed protocol could be risk factors for low ORR, which leads to a limited number of embryos and more cycle cancellations.

A ZP1 gene mutation in a patient with empty follicle syndrome: A case report and literature review

Genuine empty follicle syndrome (gEFS) is a rare cause of female infertility; it is defined as the presence of cumulus-oocyte complexes (COCs) in follicular fluid but the absence of oocytes after denudation in an in vitro fertilization (IVF) programme. Mutations in one of the four genes encoding zona pellucida (ZP) proteins have been implicated in gEFS. The objectives of the present study were to explore the molecular basis of idiopathic infertility in a 35-year-old woman with gEFS (observed after four ovarian retrievals), compare her phenotype and genotype with those of other patients described in the literature, and discuss therapeutic approaches that could be adopted by reproductive health centres in this situation. Sequencing of the ZP genes revealed a new homozygous missense variant in ZP1: c.1097G > A;p.(Arg366Gln). The variant is located in the ZP-N domain, which is essential for ZP protein polymerization. An immunohistochemical assessment of an ovarian biopsy confirmed the absence of ZP1 protein. The novel variant appears to prevent ZP assembly, which would explain the absence of normal oocytes after denudation in our patient (and despite the retrieval of COCs). ZP gene sequencing should be considered for patients with a phenotype suggestive of gEFS. An etiological genetic diagnosis enables appropriate genetic counselling and a switch to an IVF programme (with a suitable denudation technique) or an oocyte donation programme.

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 rare cause of primary amenorrhea: LHCGR gene mutations

INTRODUCTION

The luteinizing hormone/choriogonadotropin receptor (LHCGR) plays a critical role in sexual differentiation and reproductive functions in men and women. Inactivating mutations in this gene lead to Leydig cell hypoplasia (LCH), and cause disorders of sex development (DSD) in patients with 46,XY. In this study, it was aimed to discuss the clinical, laboratory and molecular genetic analysis results of nine patients with 46,XY karyotype who had mutations in the LHCGR gene.

MATERIALS AND METHODS

The ages, complaints, anthropometric measurements and hormonal results (follicle stimulating hormone (FSH), luteinizing hormone (LH), testosterone) of the patients at the time of admission were recorded retrospectively from their medical records. The mutations in the LHCGR gene were investigated using the Sanger sequencing method.

FINDINGS

In this study, LHCGR gene mutations were detected in a total of nine patients as a result of the analysis of the index patients presenting with primary amenorrhea from four different families and the examination of the families. In the first three families with no consanguinity between, the same mutation was detected in seven patients in total (Homozygous c.161 + 4A > G). A different mutation was detected in the fourth family (Homozygous p.A483D c.1448C > A).

CONCLUSION

In this study, nine patients with karyotype 46,XY, most of whom presented with the complaint of delayed puberty/primary amenorrhea, were diagnosed with LCH. Especially in patients, in whom the elevation of LH is pronounced and there is no testosterone synthesis, LCH should be considered.

Oocyte maturation abnormalities - A systematic review of the evidence and mechanisms in a rare but difficult to manage fertility pheneomina

A small proportion of infertile women experience repeated oocyte maturation abnormalities (OMAS). OMAS include degenerated and dysmorphic oocytes, empty follicle syndrome, oocyte maturation arrest (OMA), resistant ovary syndrome and maturation defects due to primary ovarian insufficiency. Genetic factors play an important role in OMAS but still need specifications. This review documents the spectrum of OMAS and to evaluate the multiple subtypes classified as OMAS. In this review, readers will be able to understand the oocyte maturation mechanism, gene expression and their regulation that lead to different subtypes of OMAs, and it will discuss the animal and human studies related to OMAS and lastly the treatment options for OMAs. Literature searches using PubMed, MEDLINE, Embase, National Institute for Health and Care Excellence were performed to identify articles written in English focusing on Oocyte Maturation Abnormalities by looking for the following relevant keywords. A search was made with the specified keywords and included books and documents, clinical trials, animal studies, human studies, meta-analysis, randomized controlled trials, reviews, systematic reviews and options written in english. The search detected 3,953 sources published from 1961 to 2021. After title and abstract screening for study type, duplicates and relevancy, 2,914 studies were excluded. The remaining 1,039 records were assessed for eligibility by full-text reading and 886 records were then excluded. Two hundred and twenty seven full-text articles and 0 book chapters from the database were selected for inclusion. Overall, 227 articles, one unpublished and one abstract paper were included in this final review. In this review study, OMAS were classified and extensively evaluatedand possible treatment options under the light of current information, present literature and ongoing studies. Either genetic studies or in vitro maturation studies that will be handled in the future will lead more informations to be reached and may make it possible to obtain pregnancies.

Genetic variants of gonadotrophins and their receptors: Impact on the diagnosis and management of the infertile patient

This narrative review is concerned with genetic variants of the genes encoding gonadotrophin subunits and their receptors, as well as their implications into the diagnosis and treatment of infertility. We first review briefly the basics of molecular biology and biochemistry of gonadotrophin and gonadotrophin receptor structure and function, then describe the phenotypic effects of polymorphisms and mutations of these genes, followed by diagnostic aspects. We will then summarise the information that inactivating gonadotrophin receptor mutations have provided about the controversial topic of extragonadal gonadotrophin action. Finally, we will close with the current and future therapeutic approaches on patients with gonadotrophin and their receptor mutations.

A novel gene mutation in ZP3 loop region identified in patients with empty follicle syndrome

The zona pellucida (ZP) is an extracellular matrix surrounding mammalian oocytes. It is composed of three to four glycoproteins, ZP1-ZP4. ZP3 is essential for sperm binding and zona matrix formation. Here, we identified a novel heterozygous mutation (NM_001110354.2:c.502_504delGAG) of ZP3, occurring in a pair of sisters with empty follicle syndrome (EFS). A mouse model with the same mutation was established using the CRISPR/Cas9 gene-editing system. As in the above family, F₀ -, F₁ -, and F₂ -generation female mice with the mutation were all infertile. Further analysis using the Chinese hamster ovary cells (CHO-K1) also showed that this mutation weakens the strength of binding between ZP3 and ZP2, which hinders the assembly of ZP and results in unstable ZP formation. Immunohistochemical analysis using ovarian serial sections in both humans and mice demonstrated that the ZP of preantral follicles was thinner than normal control, or even absent. Our study presents a new gene mutation that leads to EFS, providing new evidence and support for the genetic diagnosis of infertile individuals with similar phenotypes. Our results also show that the loop of ZP3 is not only a linker between two amphiphilic helices but may play a critical role in specifying the correct heterodimerization partner.

Case Report: A Novel Heterozygous ZP3 Deletion Associated With Empty Follicle Syndrome and Abnormal Follicular Development

Background: Empty follicle syndrome (EFS) is defined as the complete failure to retrieve oocytes after ovarian stimulation. Although several mutations in ZP1, ZP2, ZP3, and LHCGR have been identified as genetic causes of EFS, its pathogenesis is still not well-understood.

Methods: Whole-exome sequencing (WES) was employed to identify the candidate pathogenic mutations, which were then verified by Sanger sequencing. A study in CHO-K1 cells was performed to analyze the effect of the mutation on protein expression. Additionally, immunohistochemistry (IHC) staining was used to examine follicular development and zona pellucida (ZP) assembly in the ovary of an EFS patient.

Results: A novel heterozygous deletion in ZP3 (c.565_579del[p.Thr189_Gly193del]) was identified in the EFS patient. It was inherited dominantly and resulted in significant degradation of the ZP3 protein. Oocytes with degenerated cytoplasm and abnormal ZP assembly were observed in follicles up to the secondary stage, and many empty follicle-like structures were present.

Conclusion: We identified a novel ZP3 mutation that expands the mutational spectrum associated with human EFS. We also showed the abnormal follicular development and ZP assembly of the EFS patient with the heterozygous ZP3 mutation, which provides new insights into the pathogenesis of EFS.

LHCGR and ALMS1 defects likely cooperate in the development of polycystic ovary syndrome indicated by double-mutant mice

Polycystic ovary syndrome (PCOS) is a heterogeneous disorder with evidence of polygenetic components, and obesity may be a risk factor for hyperandrogenism. Previous studies have shown that LHCGR is enriched in the ovary and LHCGR deficiency causes infertility without typical PCOS phenotypes. ALMS1 is implicated in obesity and hyperandrogenism, the common phenotypes among PCOS patients. Through whole-exome sequencing of 22 PCOS families and targeted candidate gene sequencing of additional 65 sporadic PCOS patients, we identified potential causative mutations in LHCGR and ALMS1 in a sibling-pair PCOS family and three sporadic PCOS patients. The expression of LHCGR^L638P in granulosa-like tumor cell line (KGN) cells promoted cyclic adenosine monophosphate production and granulosa cell proliferation, indicating that LHCGR^L638P is an activating mutation. Lhcgr^L642P/L642P mice showed an irregular estrous cycle, reduced follicles with dynamic folliculogenesis, and increased testosterone (T), estradiol (E2), and dehydroepiandrosterone. Lhcgr^+/L642PAlms1^+/PB mice displayed increased T and E2 but decreased late secondary and preovulatory follicles. We showed that activating mutation of LHCGR likely plays important roles in the pathophysiology of PCOS involving abnormal reproductive physiology, whereas ALMS1 deficiency may promote anovulatory infertility via elevated androgens, suggesting that the disturbed LHCGR and ALMS1 cooperatively induce PCOS phenotypes, characterized as anovulation and hyperandrogenemia frequently observed in PCOS patients with obesity.

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.

Novel mutations in ZP1: Expanding the mutational spectrum associated with empty follicle syndrome in infertile women

Empty follicle syndrome (EFS) is a serious and complex reproductive complication for infertile women suffering from the recurrent failure of oocyte retrieval in an in vitro fertilization procedure, and its pathogenesis remains obscure. Increasing evidence highlights the genetic basis of EFS occurrence. In this study, we identified two novel missense mutations (c.1127G > A, p.C376Y and c.325C > T, p.R109C), two novel frameshift mutations (c.800_801delAG, p.E267Gfs*80 and c.1815_1825delGGTCCTTTTGC, p.V606Afs*42), one novel nonsense mutation (c.199G > T, p.E67Ter), and three reported mutations (c.769C > T, p.Q257Ter; c.1430 + 1G > T, p.C478Ter and c.1169_1176delTTTTCCCA, p.I390Tfs*16) in five unrelated probands, showing similar EFS manifestations, which expands the mutational spectrum of individuals with autosomal recessive ZP1. Current research will provide a better understanding of the biological functions of ZP1, and some insight into the determination of ZP1 variation as an additional rule for assessing the EFS disease.

Effect of luteinizing hormone concentration on transcriptome and subcellular organelle phenotype of ovarian granulosa cells

RESEARCH QUESTION

Granulosa cells (GCs) surrounding oocytes are crucial for follicular growth, oocyte development, ovulation, and luteinization under the dynamic co-stimulation of follicle stimulating hormone (FSH) and luteinizing hormone (LH). This study aimed to investigate the effect of LH levels on GCs in preovulatory follicles under gonadotropin releasing hormone antagonist-based ovarian stimulation. In vitro experiments were also conducted to study the direct effect of LH on GCs.

METHODS

Twelve infertile women were divided into low (L), medium (M), and high (H) LH groups according to their serum LH levels during ovarian stimulation. RNA-sequencing (RNA-seq) was conducted to examine the transcriptome profiles of GCs obtained from the above patients during the oocyte retrieval. The activity of mitochondrial dehydrogenase was measured under the stimulation of recombinant LH (rLH) concentration gradient combined with recombinant FSH. The ultrastructures of subcellular organelles were observed.

RESULTS

Bioinformatic analyses showed that compared with the M group, molecule and pathway changes in the L group and in the H group were similar. In cultured GCs, both insufficient and excessive rLH impaired the activity of mitochondrial dehydrogenase. With the medium rLH concentration, numerous cell connections and abundant mitochondria and liposomes were observed. Compared with the medium concentration, GCs showed smaller and rounder mitochondria, more autophagosomes, and massive organelles damages with excessive rLH, and swollen, circular, or forked mitochondria were observed with inadequate rLH.

CONCLUSIONS

RNA-seq provided a novel spectrum of transcriptome characteristics of GCs potentially affected by serum LH levels during ovarian stimulation. In vitro, rLH could directly affect GCs at the subcellular level.

The critical role of ZP genes in female infertility characterized by empty follicle syndrome and oocyte degeneration

OBJECTIVE

To identify the major causative gene(s) of genuine empty follicle syndrome (GEFS) characterized by oocyte degeneration.

DESIGN

Genetic and functional studies.

SETTING

University-based reproductive medicine center.

PATIENT(S)

Thirty-five unrelated women with GEFS and oocyte degeneration.

INTERVENTION(S)

Whole-exome sequencing (WES) and targeted Sanger sequencing.

MAIN OUTCOME MEASURE(S)

Variants predicted by software and the functional effects of variants assessed via Western blot and immunofluorescence in Chinese hamster ovary (CHO) cells.

RESULT(S)

We identified zona pellucida (ZP) gene variants in 18 individuals, which included 20 variants in the ZP1 gene, two variants in the ZP2 gene, and one previously reported recurrent variant in the ZP3 gene. The women carrying ZP variants constituted 51.43% of the GEFS cohort. The ZP1 variants were inherited in an autosomal recessive pattern; the ZP2 and ZP3 variants were inherited in an autosomal dominant pattern. All variants were predicted to be deleterious. Studies in CHO cells suggested that most ZP1 variants led to increased intracytoplasmic protein and some variants influenced the intracellular transportation of other ZP proteins. Variant p.R642Q of ZP2 caused the secretion of ZP2 protein with an increased molecular weight, suggesting altered protein modification. Variant p.I619N of ZP2 resulted in increased ZP2 protein in cell lysate and decreased ZP2 protein in culture medium. These results showed that ZP variants might block the intracellular transportation and secretion of ZP proteins and disrupt the zona pellucida.

CONCLUSION(S)

We identified novel variants of ZP genes in more than half the cohort with GEFS and oocyte degeneration. Variants of ZP genes caused protein intracellular sequestration and failure to assemble the ZP filaments, resulting in EFS and female infertility. Our findings not only reveal the critical roles of ZP genes but also pave the way for the efficient genetic diagnosis of females with GEFS and oocyte degeneration.

A novel mutation in ZP3 causes empty follicle syndrome and abnormal zona pellucida formation

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.

ZP1 mutations are associated with empty follicle syndrome: evidence for the existence of an intact oocyte and a zona pellucida in follicles up to the early antral stage. A case report

Empty follicle syndrome (EFS) is the complete failure to retrieve oocytes after ovarian stimulation. Although LHCGR and ZP3 were identified as causative genes, it is still unclear what happens to these patients' oocytes, and the pathogenesis of EFS remains obscure. Here, we identified six novel ZP1 mutations associated with EFS and female infertility that was inherited recessively in five unrelated families. Studies in CHO-K1 cells showed that these mutations resulted in either degradation or truncation of ZP1 protein. Immunohistochemistry using ovarian serial sections demonstrated that all preantral follicles had normal architecture, but with a thin ZP, lacking ZP1, surrounding the growing oocytes. The antral follicles were also defective in normal cumulus-oocyte complex organisation, leading us to speculate that the lack of ZP1 might lead to oocyte degeneration or increased fragility of the oocyte during follicular puncture, ultimately resulting in EFS. To our knowledge, this is the first study that presents morphological evidence showing normal preantral folliculogenesis with abnormal ZP assembly in EFS patients. Our data provides a better understanding of the biological functions of ZP1 in human ZP assembly and folliculogenesis and gives new insights into the pathogenesis of EFS and possible therapeutic developments.

Predicting suboptimal oocyte yield following GnRH agonist trigger by measuring serum LH at the start of ovarian stimulation

STUDY QUESTION

Are the LH levels at the start of ovarian stimulation predictive of suboptimal oocyte yield from GnRH agonist triggering in GnRH antagonist down-regulated cycles?

SUMMARY ANSWER

LH levels at the start of ovarian stimulation are an independent predictor of suboptimal oocyte yield following a GnRH agonist trigger.

WHAT IS KNOWN ALREADY

A GnRH agonist ovulation trigger may result in an inadequate oocyte yield in a small subset of patients. This failure can range from empty follicle syndrome to the retrieval of much fewer oocytes than expected. Suboptimal response to a GnRH agonist trigger has been defined as the presence of circulating LH levels <15 IU/l 12 h after triggering. It has been shown that patients with immeasurable LH levels on trigger day have an up to 25% risk of suboptimal response.

STUDY DESIGN, SIZE, DURATION

In this retrospective cohort study, all patients (n = 3334) who received GnRH agonist triggering (using Triptoreline 0.2 mg) for final oocyte maturation undergoing a GnRH antagonist cycle in our centre from 2011 to 2017 were included. The primary outcome of the study was oocyte yield, defined as the ratio between the total number of collected oocytes and the number of follicles with a mean diameter >10 mm prior to GnRH agonist trigger.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The endocrine profile of all patients was studied at initiation as well as at the end of ovarian stimulation. In order to evaluate whether LH levels, not only at the end but also at the start, of ovarian stimulation predicted oocyte yield, we performed multivariable regression analysis adjusting for the following confounding factors: female age, body mass index, oral contraceptives before treatment, basal and trigger day estradiol levels, starting FSH levels, use of highly purified human menopausal gonadotrophin and total gonadotropin dose. Suboptimal response to GnRH agonist trigger was defined as <10th percentile of oocyte yield.

MAIN RESULTS AND THE ROLE OF CHANCE

The average age was 31.9 years, and the mean oocyte yield was 89%. The suboptimal response to GnRH agonist trigger cut-off (<10th percentile) was 45%, which was exhibited by 340 patients. Following confounder adjustment, multivariable regression analysis showed that LH levels at the initiation of ovarian stimulation remained an independent predictor of suboptimal response even in the multivariable model (adjusted OR 0.920, 95% CI 0.871-0.971). Patients with immeasurable LH levels at the start of stimulation (<0.1 IU/l) had a 45.2% risk of suboptimal response, while the risk decreased with increasing basal LH levels; baseline circulating LH <0.5 IU/L, <2 IU/L and <5 IU/L were associated with a 39.1%, 25.2% and 13.6% risk, respectively.

LIMITATIONS, REASONS FOR CAUTION

The main limitation of the study is its retrospective design.

WIDER IMPLICATIONS OF THE FINDINGS

This is the largest study of GnRH agonist trigger cycles only, since most of the previous research on the predictive value of basal LH levels was performed in dual trigger cycles. LH values should be measured prior to start of ovarian stimulation. In cases where they are immeasurable, suboptimal response to GnRH agonist trigger can be anticipated, and an individualized approach is warranted.

STUDY FUNDING/COMPETING INTEREST(S)

There was no funding and no competing interests.

TRIAL REGISTRATION NUMBER

Not applicable.

Novel mutations in LHCGR (luteinizing hormone/choriogonadotropin receptor): expanding the spectrum of mutations responsible for human empty follicle syndrome

PURPOSE

To screen novel mutations in LHCGR responsible for empty follicle syndrome and explore the pathological mechanism of mutations.

METHODS

Four affected individuals diagnosed with infertility-associated anovulation or oligo-ovulation from three independent families were recruited. Sanger sequencing was used to identify the LHCGR mutations in affected individuals. Western blot was performed to evaluate the effects of mutations on LHCGR protein levels. Immunofluorescence was done to explore the effects of mutations on LHCGR subcellular localization. The ATP levels were measured to infer the functional effects of the mutations on LHCGR.

RESULTS

In the present study, three novel biallelic mutations in LHCGR were identified in four affected individuals from three independent families with empty follicle syndrome or oligo-ovulation. All biallelic mutations were inherited from the proband of their parents. The western blot showed that the identified mutations decreased LHCGR protein level and altered the glycosylation pattern. The immunofluorescence showed an ectopic subcellular localization of LHCGR in cultured HeLa cells. Besides, the mutations in LHCGR also reduced the cellular ATP consumption.

CONCLUSION

These findings confirm previous studies and expand the mutational spectrum of LHCGR, which will provide genetic diagnostic marker for patients with empty follicle syndrome.

Novel biallelic loss-of-function variants in ZP1 identified in an infertile female with empty follicle syndrome

PURPOSE

Empty follicle syndrome (EFS) refers to the inability to obtain mature oocytes after appropriate ovarian stimulation during the process of in vitro fertilization (IVF). However, the specific cause and mechanism of action underlying EFS remain to be further explored. Herein we aimed to investigate the clinical and genetic characteristics of EFS.

METHODS

After data were collected in an infertile family, we performed whole-exome sequencing (WES) on the patient and confirmed the pathogenic mutations through Sanger sequencing. Western immunoblotting, immunofluorescence staining, and minigene assay were further used to investigate the negative effects of these mutations.

RESULTS

Absence of oocytes was observed over 2 cycles of IVF in the patient, and we evaluated the novel compound heterozygous mutations c.2T>A (p. M1K) and c.1112+1G>T of the zona pellucida glycoprotein 1 gene (ZP1, MIM# 195000) by WES. For the family under study, EFS was classified as an autosomal recessive inheritance pattern. The results of western blotting and immunofluorescence staining analyses confirmed that the missense mutation of c.2T>A [p. M1K] resulted in almost missing protein production. Additionally, using a minigene assay, we demonstrated the deleterious effect on the ZP1 gene of the splice site mutation c.1112+1G>T, which caused truncation of ZP1 protein.

CONCLUSIONS

The compound heterozygous mutations of ZP1 gene identified in this study by genetic and functional experiments constituted a novel genetic cause of EFS, and further study will expand its use in the clinical and molecular diagnoses of EFS.

A novel homozygous nonsense ZP1 variant causes human female infertility associated with empty follicle syndrome (EFS)

Background

Empty follicle syndrome (EFS) is a rare but severe condition in which no oocyte is recovered in female patients undergoing in vitro fertilization (IVF) after sufficient ovarian response to hormonal trigger. Accumulating evidence highlights the genetic basis of EFS occurrence.

Methods

In this study, we report a patient with primary infertility showing the characteristics of EFS from a consanguineous family. Under the treatment of assisted reproductive technique (ART), no oocyte was retrieved following the aspiration of mature follicles. Through whole‐exome sequencing (WES), we discovered a novel recessively transmitted mutation in ZP1 (c.769 C>T, p. Q257*).

Results

In vitro Co‐immunoprecipitation assays showed that mutant ZP1 protein failed to interact with either ZP2 or ZP3, which explains the degenerated oocytes in the patient with EFS.

Conclusion

Together, our data further expand the spectrum of ZP1 mutations that are associated with human EFS and thus provide novel insight into the diagnosis of EFS patients.

Autonomic nervous system and inflammation interaction in endometriosis-associated pain

Endometriosis is a chronic inflammatory disease. Pain is the most common symptom in endometriosis. Endometriosis-associated pain is caused by inflammation, and is related to aberrant innervation. Although the specific mechanism between endometriosis-associated pain and the interaction of aberrant innervation and inflammation remains unclear, many studies have confirmed certain correlations between them. In addition, we found that some chronic inflammatory autoimmune diseases (AIDs) such as inflammatory bowel disease (IBD) and rheumatoid arthritis (RA) share similar characteristics: the changes in dysregulation of inflammatory factors as well as the function and innervation of the autonomic nervous system (ANS). The mechanisms underlying the interaction between the ANS and inflammation have provided new advances among these disorders. Therefore, the purpose of this review is to compare the changes in inflammation and ANS in endometriosis, IBD, and RA; and to explore the role and possible mechanism of sympathetic and parasympathetic nerves in endometriosis-associated inflammation by referring to IBD and RA studies to provide some reference for further endometriosis research and treatment.

Pregnancy and Live Birth In Women With Pathogenic LHCGR Variants Using Their Own Oocytes

CONTEXT

The LH/chorionic gonadotropin receptor (LHCGR) is mainly expressed in gonads and plays important roles in estradiol production, ovulation, and luteal formation. Women with pathogenic LHCGR variants suffer from infertility, and successful fertility treatments for such women have never been reported.

OBJECTIVE

The purpose of this study was to determine whether women with pathogenic LHCGR variants can achieve successful pregnancies through in vitro fertilization.

DESIGN

Three women with LH resistance and infertility and their parents underwent exome sequencing. The biochemical characteristics and functional effects of LHCGR mutation were assessed in transfected human embryonic kidney -293T cells and primary granulosa cells.

RESULTS

All affected women harbored pathogenic LHCGR variants. The LHCGR variants lacked cell surface localization and signal transduction abilities in vitro and in vivo. After dual triggering and prolonging the interval between triggering and oocyte pick-up, all three patients achieved oocytes and high-quality embryos. After frozen embryo transfer, one woman successfully birthed twins, and one woman successfully birthed a live boy. Apart from difficulties in oocyte retrieval, no obvious abnormalities in fertilization or during embryo development and pregnancy were identified in these patients.

CONCLUSIONS

This study is, to our knowledge, the first to report successful assisted reproductive treatment of women with pathogenic LHCGR variants using their own oocytes. Our results supported that defects in LHCGR disrupted ovulation but had no effect on fertilization and embryo development.

Discovery of BAY-298 and BAY-899: Tetrahydro-1,6-naphthyridine-Based, Potent, and Selective Antagonists of the Luteinizing Hormone Receptor Which Reduce Sex Hormone Levels in Vivo

The human luteinizing hormone receptor (hLH-R) is a member of the glycoprotein hormone family of G-protein-coupled receptors (GPCRs), activated by luteinizing hormone (hLH) and essentially involved in the regulation of sex hormone production. Thus, hLH-R represents a valid target for the treatment of sex hormone-dependent cancers and diseases (polycystic ovary syndrome, uterine fibroids, endometriosis) as well as contraception. Screening of the Bayer compound library led to the discovery of tetrahydrothienopyridine derivatives as novel, small-molecule (SMOL) hLH-R inhibitors and to the development of BAY-298, the first nanomolar hLH-R antagonist reducing sex hormone levels in vivo. Further optimization of physicochemical, pharmacokinetic, and safety parameters led to the identification of BAY-899 with an improved in vitro profile and proven efficacy in vivo. BAY-298 and BAY-899 serve as valuable tool compounds to study hLH-R signaling in vitro and to interfere with the production of sex hormones in vivo.

CD4+/CD8+ mucosa-associated invariant T cells foster the development of endometriosis: a pilot study

BACKGROUND

Immune dysregulation is one of the mechanisms to promote endometriosis (EMS). Various T cell subpopulations have been reported to play different roles in the development of EMS. The mucosa-associated invariant T cell (MAIT) is an important T cell subset in the pathogenesis of various autoimmune diseases. Evidence has indicated that there are three functionally distinct MAIT subsets: CD4+, CD8+ and CD4/CD8-/- (double negative, DN) MAIT cells. Till now, the associations between endometriosis and MAIT have not been studied. Our research investigates different MAIT subpopulations in peripheral blood (PB) and peritoneal fluid (PF) from EMS patients.

METHODS

Thirty-two EMS patients and eighteen controls were included. PB and PF were collected. Tests of cytokines in plasma and PF were performed by ELISA kit. Characterisations of MAIT were done by flow cytometry. MAIT cells have been defined as CD3 + CD161 + Vα7.2+ cells. Based on CD4 and CD8 expression, they were divided into CD8⁺MAIT, CD4⁺MAIT and DN MAIT.

RESULTS

Enrichments of MAIT cells, especially CD4 and CD8 MAIT subsets were found. Moreover, CD8 MAIT cells had a high activation in the EMS group. EMS patients produced higher level of IL-8/12/17 as compared to these from controls. On the contrary, control patients exhibited an impressive upregulation of DN MAIT cells, however, these DN MAIT cells from controls showed a higher expression of PD-1. Lastly, we performed the relevance analysis, and discovered that the accumulation of PB MAIT cells positively correlated with an elevated level of serum CA125 production in EMS group.

CONCLUSION

These results suggest that different MAIT subsets play distinct roles in the progression of endometriosis.

Compound heterozygous ZP1 mutations cause empty follicle syndrome in infertile sisters

Empty follicle syndrome (EFS) is a condition in which no oocyte is retrieved from mature follicles after proper ovarian stimulation in an in vitro fertilization procedure. Genetic evidence accumulates for the etiology of recurrent EFS without pharmacological or iatrogenic problems. In this study, we present two infertile sisters in a family with EFS after three cycles of standard ovarian stimulation with human chorionic gonadotrophin and/or gonadotropin-releasing hormone agonist therapy. Via whole-exome sequencing and cosegregation test, we identified compound heterozygous mutations in the gene of ZP1 in both of the infertile sisters. Coimmunoprecipitation tests and homology modeling analysis confirmed that both mutated ZP1 disrupt the formation of oocyte zona pellucida by interrupting the interaction among ZP1, ZP2, and ZP3. We thus propose that the specific mutations in ZP1 gene render a causality for the intractable EFS.

Gonadotropins and their receptors: coevolution, genetic variants, receptor imaging, and functional antagonists

Gonadotropins belong to the family of dimeric glycoprotein hormones and regulate gonadal physiology mediated by G protein-coupled, seven-transmembrane receptors. These glycoprotein hormones are widely used in the clinic to promote ovarian follicle development and for treating some cases of male infertility. We traced the coevolution of dimeric gonadotropin hormones and their receptors, together with thyrotropin and its receptor. We updated recent findings on human genetic variants of these genes and their association with dizygotic twining, polycystic ovarian syndrome, primary ovarian insufficiency, male-limited precocious puberty, and infertility. In addition to the known physiological roles of gonadotropin-receptor signaling in gonadal tissues, we also discussed emerging understanding of extragonadal functions of gonadotropins in bones and adipose tissues, together with recent advances in in vivo imaging of gonadotropin receptors in live animals. Recent development of gonadotropin receptor agonists and antagonists were summarized with an emphasis on the development of functional antagonists for FSH receptors to alleviate osteoporosis and obesity associated with menopause.

Novel homozygous nonsense mutations in LHCGR lead to empty follicle syndrome and 46, XY disorder of sex development

Empty follicle syndrome (EFS) is a disorder associated with female infertility and presents as a complete failure to retrieve oocytes during ART cycles despite normal follicle development and careful aspiration. To date, only two EFS cases have been reported with homozygous missense mutations in the luteinizing hormone/chorionic gonadotropin receptor (LHCGR) gene, and both cases showed normal estradiol (E2) production during ovulation induction. The molecular genetic mechanisms of EFS remain unknown. Herein, we report two novel homozygous inactivating LHCGR mutations, c.736 C>T (p.Q246*) and c.846dupT (p.R283*), in two female EFS patients from unrelated consanguineous families. The probands had impaired E2 production during the ART process, which differs from previously reported EFS cases. The inactivating mutations not only led to EFS in the two female probands, but also resulted in 46, XY disorder of sex development (46, XY DSD) in their male siblings. As far as we know, this is the first report of LHCGR mutations leading to both EFS and 46, XY DSD within the same pedigree. Our findings provide researchers and clinicians with a better understanding of phenotype-genotype correlations between EFS and 46, XY DSD and the LHCGR gene.

Novel mutation in the ZP1 gene and clinical implications

PURPOSE

Empty follicle syndrome (EFS) is a complex reproductive disorder characterized by the repeated failure to aspirate oocytes from mature ovarian follicles during in vitro fertilization (IVF). In addition to some cases caused by iatrogenic problems and known genetic factors, there are still many unexplained aspects of EFS. Here, we aimed to assess the clinical and genetic characteristics of two EFS patients.

METHODS

We have characterized two primary infertility patients with EFS in a nonconsanguineous family from China. Both the patients presented similar clinical phenotypes, that is a few granulosa cells but no oocytes could be retrieved during repeated cycles with normal follicular development, E2 levels, and bioavailable hCG plasma levels. Abnormal oocytes were obtained once or twice between multiple IVF cycles. We performed Sanger sequencing of the LHCGR and ZP1~ZP4 genes in the patients, and further bioinformatics analysis was performed to identify pathogenic elements in the genes.

RESULTS

A novel mutation, c.181C>T (p.Arg61Cys), and a known mutation, c.1169_1176delTTTTCCCA (p.Ile390Thrfs*16), in the ZP1 gene were both identified in patient 2, but no mutations were identified in patient 1. The novel mutation inherited from her mother was absent in the control cohort and the ExAc database. The arginine residue is conserved at this position, and its replacement by cysteine was predicted to be deleterious. In another allele, a paternal frameshift mutation was predicted to introduce premature stop codons, resulting in the deletion of 234 amino acids from the C-terminus of the ZP1 protein.

CONCLUSIONS

Our findings presented compound heterozygous mutations in ZP1 associated with EFS and abnormal oocytes and provided further new evidence for the genetic basis of EFS and support for the genetic diagnosis of infertile individuals.

Empty Follicle Syndrome: A Challenge to Physician

Background:

Empty follicle syndrome (EFS) is a condition in which no oocytes are retrieved from normally growing ovarian follicles after ovarian stimulation. It is a rare and frustrating condition of obscure etiology.

Objective:

The objective of this study was to estimate the incidence of EFS and study factors related to it.

Design:

This was a retrospective study.

Setting:

This study was conducted in hospital-based research center.

Methods:

In 1968 in vitro fertilization cycles from January 2010 to August 2016 were studied. Agonist, antagonist, and miniflare protocols were used for the stimulation.

Results:

The incidence of EFS is 2.38% (47/1968 cycles). Antagonist protocol group (76.59%, n = 36) had highest incidence of EFS (6.69%). Literature on EFS depicts decreased ovarian reserve (DOR) as the main cause, but only 4.25% of patients had DOR in our study. Interestingly, polycystic ovary syndrome and unexplained infertility were found in 31.9% of the cases. Serum anti-Müllerian hormone (AMH) levels (mean ± standard deviation [SD]) were 4.47 ± 3.54 ng/ml, and antral follicle count (AFC) was 15.30 ± 8.07 (mean ± SD) emphasizing that diminished ovarian reserve is not the main factor for EFS. All patients (n = 95) who underwent ovum pickup on day when any patient had EFS were taken as control. Patients with EFS were compared with controls. A statistically significant difference was not observed in serum AMH (P = 0.38) and AFC (P = 0.52).

Conclusion:

EFS is an uncommon event. Antagonist cycles have higher chances of empty follicle at ovum pickup. Looking at the profile of patients in this study, we conclude that EFS is not a manifestation of DOR.

Characterization of human peritoneal monocyte/macrophage subsets in homeostasis: Phenotype, GATA6, phagocytic/oxidative activities and cytokines expression

Peritoneal macrophages play a critical role in the control of infectious and inflammatory diseases. Although recent progress on murine peritoneal macrophages has revealed multiple aspects on their origin and mechanisms involved in their maintenance in this compartment, little is known on the characteristics of human peritoneal macrophages in homeostasis. Here, we have studied by flow cytometry several features of human peritoneal macrophages obtained from the peritoneal cavity of healthy women. Three peritoneal monocyte/macrophage subsets were established on the basis of CD14/CD16 expression (CD14⁺⁺CD16⁻, CD14⁺⁺CD16⁺ and CD14^highCD16^high), and analysis of CD11b, CD11c, CD40, CD62L, CD64, CD80, CD86, CD116, CD119, CD206, HLA-DR and Slan was carried out in each subpopulation. Intracellular expression of GATA6 and cytokines (pro-inflammatory IL-6 and TNF-α, anti-inflammatory IL-10) as well as their phagocytic/oxidative activities were also analyzed, in an attempt to identify genuine resident peritoneal macrophages. Results showed that human peritoneal macrophages are heterogeneous regarding their phenotype, cell complexity and functional abilities. A direct relationship of CD14/CD16 expression, intracellular content of GATA6, and activation/maturation markers like CD206 and HLA-DR, support that the CD14^highCD16^high subset represents the mature phenotype of steady-state human resident peritoneal macrophages. Furthermore, increased expression of CD14/CD16 is also related to the phagocytic activity.

Recent developments in genetics and medically assisted reproduction: from research to clinical applications

Two leading European professional societies, the European Society of Human Genetics and the European Society for Human Reproduction and Embryology, have worked together since 2004 to evaluate the impact of fast research advances at the interface of assisted reproduction and genetics, including their application into clinical practice. In September 2016, the expert panel met for the third time. The topics discussed highlighted important issues covering the impacts of expanded carrier screening, direct-to-consumer genetic testing, voiding of the presumed anonymity of gamete donors by advanced genetic testing, advances in the research of genetic causes underlying male and female infertility, utilisation of massively parallel sequencing in preimplantation genetic testing and non-invasive prenatal screening, mitochondrial replacement in human oocytes, and additionally, issues related to cross-generational epigenetic inheritance following IVF and germline genome editing. The resulting paper represents a consensus of both professional societies involved.

Recent developments in genetics and medically-assisted reproduction: from research to clinical applications†‡

Two leading European professional societies, the European Society of Human Genetics and the European Society for Human Reproduction and Embryology, have worked together since 2004 to evaluate the impact of fast research advances at the interface of assisted reproduction and genetics, including their application into clinical practice. In September 2016, the expert panel met for the third time. The topics discussed highlighted important issues covering the impacts of expanded carrier screening, direct-to-consumer genetic testing, voiding of the presumed anonymity of gamete donors by advanced genetic testing, advances in the research of genetic causes underlying male and female infertility, utilisation of massively-parallel sequencing in preimplantation genetic testing and non-invasive prenatal screening, mitochondrial replacement in human oocytes, and additionally, issues related to cross-generational epigenetic inheritance following IVF and germline genome editing. The resulting paper represents a consensus of both professional societies involved.

A Recurrent Missense Mutation in ZP3 Causes Empty Follicle Syndrome and Female Infertility

Empty follicle syndrome (EFS) is defined as the failure to aspirate oocytes from mature ovarian follicles during in vitro fertilization. Except for some cases caused by pharmacological or iatrogenic problems, the etiology of EFS remains enigmatic. In the present study, we describe a large family with a dominant inheritance pattern of female infertility characterized by recurrent EFS. Genome-wide linkage analyses and whole-exome sequencing revealed a paternally transmitted heterozygous missense mutation of c.400 G>A (p.Ala134Thr) in zona pellucida glycoprotein 3 (ZP3). The same mutation was identified in an unrelated EFS pedigree. Haplotype analysis revealed that the disease allele of these two families came from different origins. Furthermore, in a cohort of 21 cases of EFS, two were also found to have the ZP3 c.400 G>A mutation. Immunofluorescence and histological analysis indicated that the oocytes of the EFS female had degenerated and lacked the zona pellucida (ZP). ZP3 is a major component of the ZP filament. When mutant ZP3 was co-expressed with wild-type ZP3, the interaction between wild-type ZP3 and ZP2 was markedly decreased as a result of the binding of wild-type ZP3 and mutant ZP3, via dominant negative inhibition. As a result, the assembly of ZP was impeded and the communication between cumulus cells and the oocyte was prevented, resulting in oocyte degeneration. These results identified a genetic basis for EFS and oocyte degeneration and, moreover, might pave the way for genetic diagnosis of infertile females with this phenotype.