CSB-PGBD3 Mutations Cause Premature Ovarian Failure

MicroRNA-379-5p is associate with biochemical premature ovarian insufficiency through PARP1 and XRCC6

Premature ovarian insufficiency (POI) imposes great challenges on women’s fertility and lifelong health. POI is highly heterogeneous and encompasses occult, biochemical, and overt stages. MicroRNAs (miRNAs) are negative regulators of gene expression, whose roles in physiology and diseases like cancers and neurological disorders have been recognized, but little is known about the miRNAs profile and functional relevance in biochemical POI (bPOI). In this study, the expression of miRNAs and mRNAs in granulosa cells (GCs) of bPOI women was determined by two microarrays, respectively. MiR-379-5p, PARP1, and XRCC6 were differentially expressed in GCs of bPOI as revealed by microarrays. Subsequently, functional studies demonstrated that miR-379-5p overexpression inhibited granulosa cell proliferation and attenuated DNA repair efficiency. Furthermore, both PARP1 and XRCC6 showed lower levels in GCs from patients with bPOI and were identified as executives of miR-379-5p. Therefore, our data first uncovered potentially pathogenic miR-379-5p and two novel targets PARP1 and XRCC6 in bPOI, which corroborated the significance of DNA repair for POI, and brought up an epigenetic explanation for the disease.

A homozygous donor splice-site mutation in the meiotic gene MSH4 causes primary ovarian insufficiency

Premature ovarian insufficiency (POI) is a frequent pathology that affects women under 40 years of age, characterized by an early cessation of menses and high FSH levels. Despite recent progresses in molecular diagnosis, the etiology of POI remains idiopathic in most cases. Whole-exome sequencing of members of a Colombian family affected by POI allowed us to identify a novel homozygous donor splice-site mutation in the meiotic gene MSH4 (MutS Homolog 4). The variant followed a strict mendelian segregation within the family and was absent in a cohort of 135 women over 50 years of age without history of infertility, from the same geographical region as the affected family. Exon trapping experiments showed that the splice-site mutation induced skipping of exon 17. At the protein level, the mutation p.Ile743_Lys785del is predicted to lead to the ablation of the highly conserved Walker B motif of the ATP-binding domain, thus inactivating MSH4. Our study describes the first MSH4 mutation associated with POI and increases the number of meiotic/DNA repair genes formally implicated as being responsible for this condition.

The molecular complexity of primary ovarian insufficiency aetiology and the use of massively parallel sequencing

Primary ovarian insufficiency (POI) is a frequently occurring pathology, leading to infertility. Genetic anomalies have been described in POI and mutations in numerous genes have been definitively related to the pathogenesis of the disease. Some studies based on next generation sequencing (NGS) have been successfully undertaken as they have led to identify new mutations associated with POI aetiology. The purpose of this review is to present the most relevant molecules involved in diverse complex pathways, which may contribute towards POI. The main genes participating in bipotential gonad formation, sex determination, meiosis, folliculogenesis and ovulation are described to enable understanding how they may be considered putative candidates involved in POI. Considerations regarding NGS technical aspects such as design and data interpretation are mentioned. Successful NGS initiatives used for POI studying and future challenges are also discussed.

A novel homozygous mutation in the FSHR gene is causative for primary ovarian insufficiency

OBJECTIVE

To identify the potential FSHR mutation in a Chinese woman with primary ovarian insufficiency (POI).

DESIGN

Genetic and functional studies.

SETTING

University-based reproductive medicine center.

PATIENT(S)

A POI patient, her family members, and another 192 control women with regular menstruation.

INTERVENTION(S)

Ovarian biopsy was performed in the patient. Sanger sequencing was carried out for the patient, her sister, and parents. The novel variant identified was further confirmed with the use of control subjects.

MAIN OUTCOME MEASURE(S)

Sanger sequencing and genotype analysis to identify the potential variant of the FSHR gene; hematoxylin and eosin staining of the ovarian section to observe the follicular development; Western blotting and immunofluorescence to detect FSH receptor (FSHR) expression; and cyclic adenosine monophosphate (cAMP) assay to monitor FSH-induced signaling.

RESULT(S)

Histologic examination of the ovaries in the patient revealed follicular development up to the early antral stage. Mutational screening and genotype analysis of the FSHR gene identified a novel homozygous mutation c.175C>T (p.R59X) in exon 2, which was inherited in the autosomal recessive mode from her heterozygous parents but was absent in her sister and the 192 control women. Functional studies demonstrated that in vitro the nonsense mutation caused the loss of full-length FSHR expression and that p.R59X mutant showed no response to FSH stimulation in the cAMP level.

CONCLUSION(S)

The mutation p.R59X in FSHR is causative for POI by means of arresting folliculogenesis.

Primary ovarian insufficiency in classic galactosemia: current understanding and future research opportunities

Classic galactosemia is an inborn error of the metabolism with devastating consequences. Newborn screening has been successful in markedly reducing the acute neonatal symptoms from this disorder. The dramatic response to dietary treatment is one of the major success stories of newborn screening. However, as children with galactosemia achieve adulthood, they face long-term complications. A majority of women with classic galactosemia develop primary ovarian insufficiency and resulting morbidity. The underlying pathophysiology of this complication is not clear. This review focuses on the reproductive issues seen in girls and women with classic galactosemia. Literature on the effects of classic galactosemia on the female reproductive system was reviewed by an extensive Pubmed search (publications from January 1975 to January 2017) using the keywords: galactosemia, ovarian function/dysfunction, primary ovarian insufficiency/failure, FSH, oxidative stress, fertility preservation. In addition, articles cited in the search articles and literature known to the authors was also included in the review. Our understanding of the role of galactose metabolism in the ovary is limited and the pathogenic mechanisms involved in causing primary ovarian insufficiency are unclear. The relative rarity of galactosemia makes it difficult to accumulate data to determine factors defining timing of ovarian dysfunction or treatment/fertility preservation options for this group of women. In this review, we present reproductive challenges faced by women with classic galactosemia, highlight the gaps in our understanding of mechanisms leading to primary ovarian insufficiency in this population, discuss new advances in fertility preservation options, and recommend collaboration between reproductive medicine and metabolic specialists to improve fertility in these women.

Mutations in MSH5 in primary ovarian insufficiency

Primary ovarian insufficiency (POI) is a genetically heterogeneous disorder that occurs in familial or sporadic fashion. Through whole exome sequencing in a Chinese pedigree with POI, we identified a novel homozygous missense mutation (ENST00000375755: c.1459G > T, p.D487Y) in the MSH5 gene in two sisters with POI. The homologous mutation in mice resulted in atrophic ovaries without oocytes, and in vitro functional study revealed that mutant MSH5 impaired DNA homologous recombination repair. From sanger sequencing of MSH5 in 200 sporadic POI patients, we identified three heterozygous mutations (ENST00000375755: c.1057C > A, p.L353M; c.1459G > T, p.D487Y and c.2107 A > G, p.I703V). Considering the heterozygous p.D487Y carrier in the POI pedigree was fertile, the causality of the three heterozygous mutations in POI need more evidence. Our studies confirmed that perturbation of genes involved in DNA damage repair could lead to non-syndromic POI. The underlying mechanism-inability to repair DNA damage-will receive increasing attention with respect to POI.

A potential functional association between mutant BMPR2 and primary ovarian insufficiency

Primary ovarian insufficiency (POI) affects ~1% of women in the general population. Despite numerous attempts at identifying POI genetic aetiology, coding mutations in only a few genes have been functionally related to POI pathogenesis. It has been suggested that mutant BMPR2 might contribute towards the phenotype. Several BMP15 (a BMPR2 ligand) coding mutations in human species have been related to POI pathogenesis. The BMPR2 p.Ser987Phe mutation, previously identified in a woman with POI, might therefore lead to cellular dysfunction contributing to the phenotype. To explore such an assumption, the present study assessed potential pathogenic subcellular localization/aggregation patterns associated with the p.Ser987Phe mutant form of BMPR2 in a relevant model for studying ovarian function. A significant increase in protein-like aggregation patterns was identified at the endoplasmic reticulum (ER) which permitted us to establish, for the first time, a potential functional association between mutant BMPR2 and POI aetiology. Since BMPR2 mutant forms were previously related to idiopathic pulmonary arterial hypertension, BMPR2 mutations may be related to an as-yet-to-be described syndromic form of POI involving pulmonary dysfunction. Additional assays are necessary to confirm that BMPR2 abnormal subcellular patterns are composed by aggregates.

ABBREVIATIONS

POI: primary ovarian insufficiency; ER: endoplasmic reticulum; NGS: next generation sequencing.

Genetics of primary ovarian insufficiency

Primary ovarian insufficiency (POI) is characterized by a loss of ovarian function before the age of 40 and account for one major cause of female infertility. POI relevance is continuously growing because of the increasing number of women desiring conception beyond 30 years of age, when POI prevalence is >1%. POI is highly heterogeneous and can present with ovarian dysgenesis and primary amenorrhea, or with secondary amenorrhea, and it can be associated with other congenital or acquired abnormalities. In most cases POI remains classified as idiopathic. However, the age of menopause is an inheritable trait and POI has a strong genetic component. This is confirmed by the existence of several candidate genes, experimental and natural models. The variable expressivity of POI defect may indicate that, this disease may frequently be considered as a multifactorial or oligogenic defect. The most common genetic contributors to POI are the X chromosome-linked defects. Here, we review the principal X-linked and autosomal genes involved in syndromic and non-syndromic forms of POI with the expectation that this list will soon be upgraded, thus allowing the possibility to predict the risk of an early age at menopause in families with POI.

Premature Ovarian Insufficiency: New Perspectives on Genetic Cause and Phenotypic Spectrum

Premature ovarian insufficiency (POI) is one form of female infertility, defined by loss of ovarian activity before the age of 40 and characterized by amenorrhea (primary or secondary) with raised gonadotropins and low estradiol. POI affects up to one in 100 females, including one in 1000 before the age of 30. Substantial evidence suggests a genetic basis for POI; however, the majority of cases remain unexplained, indicating that genes likely to be associated with this condition are yet to be discovered. This review discusses the current knowledge of the genetic basis of POI. We highlight genes typically known to cause syndromic POI that can be responsible for isolated POI. The role of mouse models in understanding POI pathogenesis is discussed, and a thorough list of candidate POI genes is provided. Identifying a genetic basis for POI has multiple advantages, such as enabling the identification of presymptomatic family members who can be offered counseling and cryopreservation of eggs before depletion, enabling personalized treatment based on the cause of an individual's condition, and providing better understanding of disease mechanisms that ultimately aid the development of improved treatments.

Variation analysis of EXO1 gene in Chinese patients with premature ovarian failure

Exonuclease 1 (EXO1) is required for both DNA repair and meiosis. Inactivation of EXO1 gene in mice leads to infertility. This study aimed to investigate whether variants in the EXO1 gene contribute to human premature ovarian failure (POF). The coding region of EXO1 was sequenced in 186 Han Chinese patients with non-syndromic POF. No plausible mutation was detected. The results suggest that mutations in the coding region of EXO1 may not be responsible for POF in Han Chinese women.