Homozygous missense variant in MEIOSIN causes premature ovarian insufficiency.

STUDY QUESTION: Are variants of genes involved in meiosis initiation responsible for premature ovarian insufficiency (POI)? SUMMARY ANSWER: A MEIOSIN variant participates in the pathogenesis of human POI by impairing meiosis due to insufficient transcriptional activation of essential meiotic genes. WHAT IS KNOWN ALREADY: Meiosis is the key event for the establishment of the ovarian reserve, and several gene defects impairing meiotic homologous recombination have been found to contribute to the pathogenesis of POI. Although STRA8 and MEIOISN variants have been found to associate with POI in a recent study, the condition of other meiosis initiation genes is unknown and direct evidence of variants participating in the pathogenesis of POI is still lacking. STUDY DESIGN, SIZE, DURATION: This was a retrospective genetic study. An in-house whole exome sequencing (WES) database of 1030 idiopathic POI patients was screened for variations of meiosis initiation genes. PARTICIPANTS/MATERIALS, SETTING, METHODS: Homozygous or compound heterozygous variations of genes involved in meiosis initiation were screened in the in-house WES database. The pathogenicity of the variation was verified by in vitro experiments, including protein structure prediction and dual-luciferase reporter assay. The effect of the variant on ovarian function and meiosis was demonstrated through histological analyses in a point mutation mouse model. MAIN RESULTS AND THE ROLE OF CHANCE: One homozygous variant in MEIOSIN (c.1735C>T, p.R579W) and one in STRA8 (c.258 + 1G>A), which initiates meiosis via the retinoic acid-dependent pathway, were identified in a patient with idiopathic POI respectively. The STRA8 variation has been reported in the recently published work. For the MEIOSIN variation, the dual-luciferase reporter assay revealed that the variant adversely affected the transcriptional function of MEIOSIN in upregulating meiotic genes. Furthermore, knock-in mice with the homologous mutation confirmed that the variation impacted the meiotic prophase I program and accelerated oocyte depletion. Moreover, the variant p.R579W localizing in the high-mobility group (HMG) box domain disrupted the nuclear localization of the MEIOSIN protein but was dispensable for the cell-cycle switch of oocytes, suggesting a unique role of the MEIOSIN HMG box domain in meiosis initiation. LIMITATIONS, REASONS FOR CAUTION: Further studies are needed to explore the role of other meiosis initiation genes in the pathogenesis of POI. WIDER IMPLICATIONS OF THE FINDINGS: The MEIOSIN variant was verified to cause POI by impaired transcriptional regulation of meiotic genes and was inherited by a recessive mode. The function of HMG box domain in MEIOSIN protein was also expanded by this study. Although causative variations in meiotic initiation genes are rare in POI, our study confirmed the pathogenicity of a MEIOSIN variant and elucidated another mechanism of human infertility. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by the National Key Research & Developmental Program of China (2022YFC2703800, 2022YFC2703000), National Natural Science Foundation for Distinguished Young Scholars (82125014), National Natural Science Foundation of China (32070847, 32170867, 82071609), Basic Science Center Program of NSFC (31988101), Natural Science Foundation of Shandong Province for Grand Basic Projects (ZR2021ZD33), Natural Science Foundation of Shandong Province for Excellent Young Scholars (ZR2022YQ69), Taishan Scholars Program for Young Experts of Shandong Province (tsqn202211371), and Qilu Young Scholars Program of Shandong University. The authors declare no conflict of interest. TRIAL REGISTRATION NUMBER: N/A.

TP63 gain-of-function mutations cause premature ovarian insufficiency by inducing oocyte apoptosis.

The transcription factor p63 guards genome integrity in the female germline, and its mutations have been reported in patients with premature ovarian insufficiency (POI). However, the precise contribution of the TP63 gene to the pathogenesis of POI needs to be further determined. Here, in 1,030 Chinese patients with POI, we identified 6 heterozygous mutations of the TP63 gene that impaired the C-terminal transactivation-inhibitory domain (TID) of the TAp63α protein and resulted in tetramer formation and constitutive activation of the mutant proteins. The mutant proteins induced cell apoptosis by increasing the expression of apoptosis-inducing factors in vitro. We next introduced a premature stop codon and selectively deleted the TID of TAp63α in mice and observed rapid depletion of the p63+/ΔTID mouse oocytes through apoptosis after birth. Finally, to further verify the pathogenicity of the mutation p.R647C in the TID that was present in 3 patients, we generated p63+/R647C mice and also found accelerated oocyte loss, but to a lesser degree than in the p63+/ΔTID mice. Together, these findings show that TID-related variants causing constitutive activation of TAp63α lead to POI by inducing oocyte apoptosis, which will facilitate the genetic diagnosis of POI in patients and provide a potential therapeutic target for extending female fertility.

Next-generation sequencing of 500 POI patients identified novel responsible monogenic and oligogenic variants.

BACKGROUND: Premature ovarian insufficiency refers to the loss of ovarian function before 40 years of age. The etiology is heterogeneous, and genetic factors account for 20-25% of cases. However, how to transform genetic findings to clinical molecular diagnose remains a challenge. To identify potential causative variations for POI, a next generation sequencing panel with 28 known causative genes of POI was designed, and a large cohort of 500 Chinese Han patients was screened directly. Pathogenic evaluation of the identified variants and the phenotype analysis were performed according to monogenic or oligogenic variants. RESULTS: A total of 14.4% (72/500) of the patients carried 61 pathogenic or likely pathogenic variants in 19 of the genes in the panel. Interestingly, 58 variants (95.1%, 58/61) were firstly identified in patients with POI. FOXL2 harbored the highest occurrence frequency (3.2%, 16/500), among whom presented with isolated ovarian insufficiency instead of blepharophimosis-ptosis-epicanthus inversus syndrome. Moreover, luciferase reporter assay confirmed variant p.R349G, which account for 2.6% of POI cases, impaired the transcriptional repressive effect of FOXL2 on CYP17A1. The novel compound heterozygous variants in NOBOX and MSH4 were confirmed by pedigree haplotype analysis, and digenic heterozygous variants in MSH4 and MSH5 were firstly identified. Furthermore, nine patients (1.8%, 9/500) with digenic or multigenic pathogenic variants presented with delayed menarche, early onset of POI and high prevalence of primary amenorrhea compared with those with monogenic variation(s). CONCLUSIONS: The genetic architecture of POI has been enriched through the targeted gene panel in a large cohort of patients with POI. Specific variants in pleiotropic genes may result in isolated POI rather than syndromic POI, whereas oligogenic defects might have cumulative deleterious effects on the severity of POI phenotype.

Landscape of pathogenic mutations in premature ovarian insufficiency.

Premature ovarian insufficiency (POI) is a major cause of female infertility due to early loss of ovarian function. POI is a heterogeneous condition, and its molecular etiology is unclear. To identify genetic variants associated with POI, here we performed whole-exome sequencing in a cohort of 1,030 patients with POI. We detected 195 pathogenic/likely pathogenic variants in 59 known POI-causative genes, accounting for 193 (18.7%) cases. Association analyses comparing the POI cohort with a control cohort of 5,000 individuals without POI identified 20 further POI-associated genes with a significantly higher burden of loss-of-function variants. Functional annotations of these novel 20 genes indicated their involvement in ovarian development and function, including gonadogenesis (LGR4 and PRDM1), meiosis (CPEB1, KASH5, MCMDC2, MEIOSIN, NUP43, RFWD3, SHOC1, SLX4 and STRA8) and folliculogenesis and ovulation (ALOX12, BMP6, H1-8, HMMR, HSD17B1, MST1R, PPM1B, ZAR1 and ZP3). Cumulatively, pathogenic and likely pathogenic variants in known POI-causative and novel POI-associated genes contributed to 242 (23.5%) cases. Further genotype-phenotype correlation analyses indicated that genetic contribution was higher in cases with primary amenorrhea compared to that in cases with secondary amenorrhea. This study expands understanding of the genetic landscape underlying POI and presents insights that have the potential to improve the utility of diagnostic genetic screenings.

Pathogenic variants in TSC2 might cause premature ovarian insufficiency through activated mTOR induced hyperactivation of primordial follicles.

OBJECTIVE: To investigate the role of tuberous sclerosis complex (TSC) genes, including TSC1 and TSC2, in the pathogenesis of human premature ovarian insufficiency (POI). DESIGN: Genetic and functional study. SETTING: University-based reproductive medical center. PATIENT(S): Six patients from a cohort of 1,030 cases with idiopathic POI. INTERVENTION(S): Variants in TSC1 and TSC2 were screened through the largest in-house database of whole exome sequencing performed in 1,030 patients with idiopathic POI. The pathogenic effects of the variants were further verified by functional studies. MAIN OUTCOME MEASURE(S): TSC1 or TSC2 variant and functional characteristics. RESULT(S): Five pathogenic heterozygous variants in TSC2 were identified in 6 patients with POI. Functional studies showed these variants impaired the repressive effect of TSC2 on mammalian target of rapamycin (mTOR) pathway by disrupting the formation of TSC complex or its GTPase-activating protein activity. Furthermore, in vitro ovarian culture assay showed that TSC2 p.R98Q led to hyperactivation of mTOR pathway thereby triggering primordial follicle activation. CONCLUSION(S): The present study identified pathogenic variants of TSC2 in patients with POI, firstly suggested defective TSC/mTOR pathway mediated hyperactivation of primordial follicle participating in the pathogenesis of POI, giving insights into new targets of genetic counseling and clinical prevention for POI. Considering the pivotal role of TSC2 variants in diagnosis of TSC syndrome, the present study also highlighted the importance of history collection and long-term follow-up for the TSC2 variants carriers.

Homozygous Variant in KASH5 Causes Premature Ovarian Insufficiency by Disordered Meiotic Homologous Pairing.

CONTEXT: Premature ovarian insufficiency (POI) affects 1% to 3.7% of women at reproductive age, and its etiology is heterogeneous. The linker of nucleoskeleton and cytoskeleton (LINC) complex, consisting of KASH5 and SUN1, plays an indispensable role in meiotic homolog pairing, determining the ovarian reserve. However, their roles in the pathogenesis of POI are unknown. OBJECTIVE: To investigate the role of KASH5 variation in the pathogenesis of POI. DESIGN: Whole-exome sequencing was performed in a pedigree with 2 POI patients. The pathogenicity of identified variant was illustrated by in vitro functional studies, and its effect on ovarian function and meiosis was confirmed by histological analysis and oocyte spreads with Kash5 C-terminal deleted mice model. RESULTS: A homozygous splicing site variant in KASH5 (c.747G > A) was identified. In vitro studies found the variant disturbed the nuclear membrane localization of KASH5 and its binding with SUN1. Moreover, the Kash5 C-terminal deleted mice revealed defective meiotic homolog pairing and accelerated depletion of oocytes. CONCLUSIONS: The splicing site variant in KASH5 is responsible for POI due to defective meiotic homolog pairing and accelerated depletion of oocytes. Our study is the first to report disorganized LINC complex participating in POI pathogenesis, potentially suggesting the essential roles of meiotic telomere attachment and dynein-driven proteins for chromosome movement in ovarian function maintenance.

Autophagy regulates differentiation of ovarian granulosa cells through degradation of WT1.

Ovarian granulosa cells (GCs) proliferate and differentiate along with follicular growth, and this is indispensable for oocyte development and female fertility. Although the role of macroautophagy/autophagy in ovarian function has been reported, its contribution to the regulation of GC characteristics remains elusive. The siRNA-mediated knockdown of two key autophagy-related genes ATG5 and BECN1 and the autophagy inhibitor chloroquine were used to interfere with autophagy in GCs. Inhibition of autophagy both genetically and pharmacologically resulted in decreased expression of genes associated with GC differentiation, including CYP19A1/Aromatase and FSHR, as well as in reduced estradiol synthesis. Mechanistically, when autophagy was disrupted, the transcription factor WT1 accumulated in GCs due to its insufficient degradation by the autophagic pathway, and this inhibited GC differentiation. Finally, decreased expression of several autophagy-related genes, as well as reduced LC3-II:LC3-I and elevated SQSTM1/p62 protein levels, which are indications of decreased autophagy, were detected in GCs from biochemical premature ovarian insufficiency patients. In summary, our study reveals that autophagy regulates the differentiation of ovarian GCs by degrading WT1 and that insufficient autophagy might be involved in ovarian dysfunction.Abbreviations: ATG: autophagy related; bPOI: biochemical premature ovarian insufficiency; CHX: cycloheximide; Co-IP: co-immunoprecipitation; CQ: chloroquine; E2: estradiol; FSH: follicle stimulating hormone; FSHR: follicle stimulating hormone receptor; GC: granulosa cell; LIR: LC3-interacting region; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; POI: premature ovarian insufficiency; RAP: rapamycin; siRNA: small interfering RNA; WT1: WT1 transcription factor.

Variations of C14ORF39 and SYCE1 Identified in Idiopathic Premature Ovarian Insufficiency and Nonobstructive Azoospermia.

CONTEXT: Premature ovarian insufficiency (POI) and nonobstructive azoospermia (NOA) are the most severe diseases causing irreversible infertility in females and males, respectively. The contribution of synaptonemal complex (SC) gene variations in the pathogenesis of sporadic patients with POI and NOA has not been systematically illustrated. OBJECTIVE: To investigate the role of SC genes in the pathogenesis of sporadic POI and NOA. DESIGN: Genetic and functional study. SETTING: University-based reproductive medicine center. PATIENT(S): A total of 1030 patients with sporadic POI and 400 patients with sporadic NOA. INTERVENTION(S): The variations of SC genes were filtered in the in-house database of whole exome sequencing performed in 1030 patients with sporadic POI and 400 patients with sporadic NOA. The pathogenic or likely pathogenic variations following recessive inheritance mode were selected according to American College of Medical Genetics and Genomics (ACMG) guidelines and confirmed by Sanger sequencing. The pathogenic effects of the variations were verified by functional studies. MAIN OUTCOME MEASURE(S): ACMG classification and functional characteristics. RESULT(S): Two homozygous variations of C14ORF39 and 2 recessive variations of SYCE1 were first identified in sporadic patients with POI and NOA, respectively. Functional studies showed the C14ORF39 variations significantly accelerated the protein degradation and the variations in SYCE1 disrupted its interaction with SYCP1 or C14ORF39, both of which affected SC assembly and meiosis. CONCLUSION(S): Our study identified novel pathogenic variations of C14ORF39 and SYCE1 in sporadic patients with POI or NOA, highlighting the essential role of SC genes in the maintenance of ovarian and testicular function.

Pathogenic variants of meiotic double strand break (DSB) formation genes PRDM9 and ANKRD31 in premature ovarian insufficiency.

PURPOSE: The etiology of premature ovarian insufficiency (POI) is heterogeneous, and genetic factors account for 20-25% of the patients. The primordial follicle pool is determined by the meiosis process, which is initiated by programmed DNA double strand breaks (DSB) and homologous recombination. The objective of the study is to explore the role of DSB formation genes in POI pathogenesis. METHODS: Variants in DSB formation genes were analyzed from a database of exome sequencing in 1,030 patients with POI. The pathogenic effects of the potentially causative variants were verified by further functional studies. RESULTS: Three pathogenic heterozygous variants in PRDM9 and two in ANKRD31 were identified in seven patients. Functional studies showed the variants in PRDM9 impaired its methyltransferase activity, and the ANKRD31 variations disturbed its interaction with another DSB formation factor REC114 by haploinsufficiency effect, indicating the pathogenic effects of the two genes on ovarian function were dosage dependent. CONCLUSION: Our study identified pathogenic variants of PRDM9 and ANKRD31 in POI patients, shedding new light on the contribution of meiotic DSB formation genes in ovarian development, further expanding the genetic architecture of POI.

TMEM150B is dispensable for oocyte maturation and female fertility in mouse.

Premature ovarian insufficiency (POI) refers to severe decline of ovary function in females which usually leads to infertility. It has been reported that the TMEM150B gene is mostly associated with age at natural menopause, early menopause and POI, but its role in female reproduction remains unknown. In this study, we found Tmem150b was highly expressed in mouse oocytes, but its deletion had no obvious effect on meiotic maturation of oocytes indicated by first polar body emission and spindle morphology. There were also no obvious differences in follicle development and corpus luteum formation between knockout and wild type mice. Finally, knockout of Tmem150b did not affect female fertility and sexual hormone levels. In summary, our results suggest that TMEM150B is not essential for female fertility in mice.

Rare deleterious BUB1B variants induce premature ovarian insufficiency and early menopause.

Losing of ovarian functions prior to natural menopause age causes female infertility and early menopause. Premature ovarian insufficiency (POI) is defined as the loss of ovarian activity before 40 years of age. Known genetic causes account for 25-30% of POI cases, demonstrating the high genetic heterogeneity of POI and the necessity for further genetic explorations. Here we conducted genetic analyses using whole-exome sequencing in a Chinese non-syndromic POI family with the affected mother and at least four affected daughters. Intriguingly, a rare missense variant of BUB1B c.273A>T (p.Gln91His) was shared by all the cases in this family. Furthermore, our replication study using targeted sequencing revealed a novel stop-gain variant of BUB1B c.1509T>A (p.Cys503*) in one of 200 sporadic POI cases. Both heterozygous BUB1B variants were evaluated to be deleterious by multiple in silico tools. BUB1B encodes BUBR1, a crucial spindle assembly checkpoint component involved in cell division. BUBR1 insufficiency may induce vulnerability to oxidative stress. Therefore, we generated a mouse model with a loss-of-function mutant of Bub1b, and also employed D-galactose-induced aging assays for functional investigations. Notably, Bub1b+/- female mice presented late-onset subfertility, and they were more sensitive to oxidative stress than wild-type female controls, mimicking the clinical phenotypes of POI cases affected by deleterious BUB1B variants. Our findings in human cases and mouse models consistently suggest, for the first time, that heterozygous deleterious variants of BUB1B are involved in late-onset POI and related disorders.

FANCL gene mutations in premature ovarian insufficiency.

The Fanconi anemia (FA) pathway is mainly involved in DNA interstrand crosslinks (ICLs) repair in the genome. Several FA genes, including FANCD1/BRCA2, FANCM, and FANCU/XRCC2, have been identified as causative genes for premature ovary insufficiency (POI). Fanconi anemia group L protein (FANCL) cooperates with FANCT/UBE2T to ubiquitinate the FANCI-D2 dimer, which is a crucial event in the process of ICLs repair. Fancl-knockout mice phenocopy human POI, but the role of FANCL mutations in POI pathogenesis has not been confirmed. In the present work, potentially pathogenic mutations in the FANCL gene were screened in 200 Chinese patients with idiopathic POI and in 200 matched controls. Two novel heterozygous frameshift mutations, c.1048_1051delGTCT (p.Gln350Valfs*18) and c.739dupA (p.Met247Asnfs*4), were identified in the FANCL gene in POI patients but not in controls. Wild-type FANCL protein was predominantly localized in the nuclei, while both mutant FANCL proteins were retained in the cytoplasm. In addition, the FANCL variants exhibited impaired ubiquitin-ligase activity and compromised DNA repair ability after mitomycin C treatment. Furthermore, the FANCL variants were deleterious and might be associated with haploinsufficiency. Our results show that FANCL mutations are potentially causative for POI by disrupting DNA damage repair processes.

Impact of Thyroid Autoimmunity on Ovarian Reserve, Pregnancy Outcomes, and Offspring Health in Euthyroid Women Following In Vitro Fertilization/Intracytoplasmic Sperm Injection.

Background: Thyroid autoimmunity (TAI) is the most frequent autoimmune disease among reproductive-aged women. It has been related to premature ovarian insufficiency, but the mechanisms remain elusive, and its association with ovarian reserve in euthyroid women is debatable. Moreover, the impact of TAI on assisted reproduction is controversial: especially for women with diminished ovarian reserve (DOR), few studies are available. Therefore, the present study was aimed to look for an association between TAI and DOR, and to evaluate the effect of TAI on pregnancy outcomes and offspring health following assisted reproductive technology stratified by ovarian reserve. Methods: A total of 6213 euthyroid women from the Reproductive Hospital Affiliated to Shandong University between 2012 and 2017 were retrospectively included. The prevalence of DOR in women with negative or positive TAI was calculated, and pregnancy and neonatal outcomes after in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) cycles were compared between the TAI-positive and TAI-negative groups both in women with DOR and in those with normal ovarian reserve (NOR). Longitudinal growth parameters and temperament type of the offspring were also observed in the TAI-positive and TAI-negative groups. Results: The prevalence of DOR in women with positive TAI and those with negative TAI was not significantly different (4.09% vs. 2.96%, p = 0.053), even after stratifying patients by age. In women with DOR, the live birth rate, pregnancy loss rate, neonatal complication rate, and offspring outcomes between the TAI-positive and TAI-negative groups were comparable (p > 0.05). In women with NOR, a higher rate of live births (44.94% vs. 40.34%, p = 0.027) and a higher prevalence of congenital anomalies (4.68% vs. 2.14%, p = 0.005) were observed in the TAI-positive group. Conclusions: TAI had no impact on ovarian reserve in euthyroid women and had no association with IVF/ICSI outcomes in women with DOR. Although an increased incidence of congenital anomalies in the TAI-positive group was observed in women with NOR, an association between neonatal anomalies and TAI cannot be demonstrated. Large cohort studies to evaluate the effects of TAI on offspring health are warranted, and further experimental studies are required to explore the underlying mechanisms.

A novel FOXL2 mutation in two infertile patients with blepharophimosis-ptosis-epicanthus inversus syndrome.

BACKGROUND: Blepharophimosis-ptosis-epicanthus inversus syndrome (BPES) is a rare, autosomal dominant disease. There are two clinical types of BPES: type I patients have eyelid abnormalities accompanied by infertility in affected females, while type II patients only display eyelid malformations. Previous studies have reported that the forkhead box L2 (FOXL2) gene mutations cause BPES. PURPOSE: To identify plausible FOXL2 mutation in a Chinese family with BPES and infertility METHODS: Mutational screening of FOXL2 was performed in the affected members and 223 controls. Functional characterization of the novel mutation identified was carried out in vitro by luciferase reporter assay and subcellular localization experiment. RESULTS: A novel heterozygous mutation c.188 T > A (p.I63N) in FOXL2 was identified in two BPES patients in this family. The mutation abolished the transcriptional repression of FOXL2 on the promoters of CYP19A1 and CCND2 genes, as shown by luciferase reporter assays. However, no dominant-negative effect was observed for the mutation, and it did not impact FOXL2 protein nuclear localization and distribution. CONCLUSIONS: The mutation c.188 T > A (p.I63N) in FOXL2 might be causative for BPES and infertility in this family and further amplified the spectrum of FOXL2 mutations.

Correction: Wdr62 is involved in female meiotic initiation via activating JNK signaling and associated with POI in humans.

[This corrects the article DOI: 10.1371/journal.pgen.1007463.].

Palmitic acid causes insulin resistance in granulosa cells via activation of JNK.

Obesity is a worldwide health problem with rising incidence and results in reproductive difficulties. Elevated saturated free fatty acids (FFAs) in obesity can cause insulin resistance (IR) in peripheral tissues. The high intra-follicular saturated FFAs may also account for IR in ovarian granulosa cells (GCs). In the present study, we investigated the relationship between saturated FFAs and IR in GCs by the use of palmitic acid (PA). We demonstrated that the glucose uptake in cultured GCs and lactate accumulation in the culture medium were stimulated by insulin, but the effects of insulin were attenuated by PA treatment. Besides, insulin-induced phosphorylation of Akt was reduced by PA in a dose- and time-dependent manner. Furthermore, PA increased phosphorylation of JNK and JNK blockage rescued the phosphorylation of Akt which was downregulated by PA. These findings highlighted the negative effect of PA on GCs metabolism and may partially account for the obesity-related reproductive disorders.

Variation analysis of theTMEM150B gene in Chinese women with premature ovarian insufficiency.

RESEARCH QUESTION: The TMEM150B gene, which promotes cell survival under stress conditions by modulating autophagy, is closely associated with age at natural menopause, early menopause and premature ovarian insufficiency (POI) in European women. However, whether gene variants of TMEM150B contribute to the pathogenesis of POI needs to be determined. DESIGN: A case-control genetic study in 408 Han Chinese women with non-syndromic POI, in which all exons and exon-intron boundaries of the TMEM150B gene were screened by Sanger sequencing; the results were analysed by statistics and bioinformatics. RESULTS: Two novel variants located in the 3' untranslated region of the TMEM150B gene were identified, but bioinformation analyses showed that neither was potentially disease-causing. Six known single-nucleotide polymorphisms (SNP) were found, and they were not potentially causative for POI. The intronic SNP rs11668344 was also detected in the POI patients; no significant differences were found in either genotype or allele frequencies compared with the control population. CONCLUSION: The results suggest that the perturbations in the TMEM150B gene are not a common explanation for POI in Chinese women. The role of autophagy in the pathogenic mechanism of POI needs further exploration.

Molecular Genetics of Premature Ovarian Insufficiency.

Premature ovarian insufficiency (POI) is highly heterogeneous in genetic etiology. Yet identifying causative genes has been challenging with candidate gene approaches. Recent approaches using next generation sequencing (NGS), especially whole exome sequencing (WES), in large POI pedigrees have identified new causatives and proposed relevant candidates, mainly enriched in DNA damage repair, homologous recombination, and meiosis. In the near future, NGS or whole genome sequencing will help better define genes involved in intricate regulatory networks. The research into miRNA and age at menopause represents an emerging field that will help unveil the molecular mechanisms underlying pathogenesis of POI. Shedding light on the genetic architecture is important in interpreting pathogenesis of POI, and will facilitate risk prediction for POI.

Wdr62 is involved in female meiotic initiation via activating JNK signaling and associated with POI in humans.

Meiosis is a germ cell-specific division that is indispensable for the generation of haploid gametes. However, the regulatory mechanisms of meiotic initiation remain elusive. Here, we report that the Wdr62 (WD40-repeat protein 62) is involved in meiotic initiation as a permissive factor rather than an instructive factor. Knock-out of this gene in a mouse model resulted in female meiotic initiation defects. Further studies demonstrated that Wdr62 is required for RA-induced Stra8 expression via the activation of JNK signaling, and the defects in meiotic initiation from Wdr62-deficient female mice could be partially rescued by JNK1 overexpression in germ cells. More importantly, two novel mutations of the WDR62 gene were detected in patients with premature ovarian insufficiency (POI), and these mutations played dominant-negative roles in regulating Stra8 expression. Hence, this study revealed that Wdr62 is involved in female meiotic initiation via activating JNK signaling, which displays a novel mechanism for regulating meiotic initiation, and mutation of WDR62 is one of the potential etiologies of POI in humans.

Variation analysis of PUM1 gene in Chinese women with primary ovarian insufficiency.

Accumulating evidence has indicated that the genes involved in meiosis are highly correlated with ovarian function. Pumilio 1 (PUM1) is a RNA-binding protein which is involved in the meiotic process. It has been reported that the Pum1 knockout female mice displayed subfertility due to the decrease in primordial follicle pool. The aim of our study is to investigate whether variants of the PUM1 gene are responsible for primary ovarian insufficiency (POI) in Chinese women. We analyzed coding sequence and untranslated regions of the PUM1 gene in 196 Han Chinese women with non-syndromic POI and 192 controls. Seven novel variants were identified, but one of them was synonymous and six were intronic. Besides, seven known single-nucleotide polymorphisms (SNPs) were found, and there were no significant differences in genotype and allele frequencies of the SNPs between patients and controls. The results suggest that the variants in PUM1 may not contribute to POI in Han Chinese women.