INHA promoter polymorphisms are associated with premature ovarian failure

Candidate genes associated with reproductive traits in rabbits

In the era of scientific advances and genetic progress, opportunities in the livestock sector are constantly growing. The application of molecular-based methods and approaches in farm animal breeding would accelerate and improve the expected results. The current work aims to comprehensively review the most important causative mutations in candidate genes that affect prolificacy traits in rabbits. Rabbits are a source of excellent-tasting meat that is high in protein and low in fat. Their early maturity and intensive growth are highly valued all over the world. However, improving reproductive traits and prolificacy in rabbits could be very tricky with traditional selection. Therefore, traditional breeding programs need new methods based on contemporary discoveries in molecular biology and genetics because of the complexity of the selection process. The study and implementation of genetic markers related to production in rabbits will help to create populations with specific productive traits that will produce the desired results in an extremely short time. Many studies worldwide showed an association between different genes and productive traits in rabbits. The study of these polymorphisms and their effects could be useful for molecular-oriented breeding, particularly marker-assisted selection programs in rabbit breeding.

Identification of Novel Nucleotide Changes in INHBB Gene by Mutation Screening in Females with Ovarian Dysgenesis: A Case Report

Background:

Inhibin and activin regulate the follicle stimulating hormone level by their antagonistic actions and thus have been considered as strong candidate genes in the etiology of ovarian dysgenesis. In the present study, two cases of primary amenorrhea with poorly developed secondary sexual characteristics were reported. The purpose of the study was to identify mutations in candidate gene.

Case Presentation:

In this paper, clinical, genetic, biochemical, and molecular findings in female patients with primary amenorrhea were reported. Whole blood culture and G-banding for karyotyping, sequencing, and in silico analysis were performed following the standard protocol. Both cases were cytogenetically characterized as normal females with 46,XX, chromosome constitution. Hormonal assay revealed high level of follicle stimulating hormone and luteinizing hormone. DNA sequence analysis of inhibin identified two novel heterozygous missense mutations of c.975T>A and c.1156G>A which were translated into p.I310N and p.D386N, respectively. These identified positions were highly conserved across species during evolution. In silico prediction tools, intramolecular hydrogen bonding pattern and hydrophobicity analysis, revealed deleterious effect of p.I310N and neutral effect of p.D386N mutation.

Conclusion:

Our observation suggested that identified novel mutation in the first case might be the reason for ovarian dysgenesis and provides additional support to the previously reported genotype-phenotype correlations.

Rescuing lethal phenotypes induced by disruption of genes in mice: a review of novel strategies

Approximately 35 % of the mouse genes are indispensable for life, thus, global knock-out (KO) of those genes may result in embryonic or early postnatal lethality due to developmental abnormalities. Several KO mouse lines are valuable human disease models, but viable homozygous mutant mice are frequently required to mirror most symptoms of a human disease. The site-specific gene editing systems, the transcription activator-like effector nucleases (TALENs), Zinc-finger nucleases (ZFNs) and the clustered regularly interspaced short palindrome repeat-associated Cas9 nuclease (CRISPR/Cas9) made the generation of KO mice more efficient than before, but the homozygous lethality is still an undesired side-effect in case of many genes. The literature search was conducted using PubMed and Web of Science databases until June 30th, 2020. The following terms were combined to find relevant studies: "lethality", "mice", "knock-out", "deficient", "embryonic", "perinatal", "rescue". Additional manual search was also performed to find the related human diseases in the Online Mendelian Inheritance in Man (OMIM) database and to check the citations of the selected studies for rescuing methods. In this review, the possible solutions for rescuing human disease-relevant homozygous KO mice lethal phenotypes were summarized.

Association of polymorphism c.-124G>A and c.-16 C>T in the promoter region of human INHA gene with altered sperm parameters; A pilot study

OBJECTIVE

The objective of this was to demonstrate the association of Inhibin α (INHα) c.-124G>A and INHα-c.-16 C>T polymorphisms with altered sperm parameters in a selected male population of Karachi, Pakistan.

STUDY DESIGN & SETTINGS

In this pilot study, male subjects were stratified on the basis of the WHO criteria for altered sperm parameters; 83 (cases-altered sperm parameters) and 30 (controls-normal sperm parameters) subjects were included for analysis of INHα-c.124G>A polymorphism and 88 (cases) and 38 (controls) were analysed for INHα -c-16 C>T polymorphism. Genotyping of INHα-c.-124G>A and INHα-c.-16 C>T was performed by PCR-RFLP, genotype distribution in Hardy-Weinberg equilibrium was evaluated by binary logistic regression model.

RESULTS

For the c.-124G>A polymorphism in INHα gene, frequency of the three major genotypes in controls was: GG: 80.0%, GA: 20.0% and AA: 0% and in cases was: GG: 59.0%, GA: 30.2% and AA: 10.8%. The GG genotype was significantly associated with male infertility (P < .045, OR = 2.776, 95% CI = 1.025-7.513) while the GA genotype was not significantly associated with infertility (P < .290 OR = 0.580, 95% CI = 0.211-1.593). Frequency of mutant AA genotype was 10.8% in cases (altered sperm parameters) and absent (0%) in normal sperm parameter (controls). The frequencies of three major genotypes CC, CT and TT did not show any significant difference between cases and controls (P > .05).

CONCLUSION

The results from our study exhibited a significant association of c.-124G>A polymorphism in the INHα gene promoter region with male infertility in the Pakistani population. A significant association of c.-16 C>T polymorphism with male infertility, however, was not observed. Further large-scale studies should be conducted to confirm this association.

Polymorphisms of four candidate genes and their correlations with growth traits in blue fox (Alopex lagopus)

To improve the accuracy and genetic progress of blue fox breeding, the relationships between genetic polymorphisms and growth and reproductive traits of the blue fox were investigated. MC4R, MC3R, INHA and INHBA were selected as candidate genes for molecular evolution and statistical analyses. Single-factor variance analyses showed that the MC4R (g.267C > T, g.423C > T, and g.731C > A) and MC3R (g.677C > T) genotypes had significant impacts on body weight, chest circumference, abdominal perimeter and body mass index (BMI) (P < 0.05) in blue fox. The MC4R and MC3R combined genotypes had significant effects on the body weight and abdominal circumference. The different genotypes of INHA g.75G > A had significant effects on female fecundity, whereas the different genotypes of INHBA g.404G > T and g.467G > T and the INHA and INHBA combined genotypes had significant effects on male fecundity. The proteins encoded by the open reading frames (ORFs) of different polymorphic loci were predicted and analysed. The aims of this study were to identify genetic markers related to growth and reproduction in the blue fox and to provide an efficient, economical and accurate theoretical approach for auxiliary fox breeding.

Analysis of Expression and Single Nucleotide Polymorphisms of INHA Gene Associated with Reproductive Traits in Chickens

Inhibin α (INHA) is a candidate gene controlling ovulation in poultry. As the functional center of inhibin, INHA is a molecular marker associated with egg-laying performance. The objective of the current study was to analyze the expression differences of INHA in reproductive system and single nucleotide polymorphisms (SNPs) associations with reproductive traits in chickens. A total of 260 LuHua chickens (barred-feather chicken) were adopted. Twelve SNPs were detected in INHA gene. Among the exonic SNPs, three (g. 22177991A>G, g. 22178249G>C, and g. 22178414G>A) were missense mutations, resulting in the amino acid substitutions Val→Ala, Ala→Gly, and Ala→Gly, respectively. Four SNPs in the 3＇ untranslated region of INHA were predicted to either disturb or create microRNA-target interactions. Five SNPs (g. 22176870T>C, g. 22177100T>C, g. 22177149T>C, g. 22177991A>G, and g. 22178975G>A) were significantly associated with the number of eggs at 300 d of age (EN) (P < 0.05). Birds carrying GA genotype exhibited more EN than those with AA genotype (P < 0.01). In addition, quantitative real-time PCR revealed that INHA is mainly expressed in follicles on d 300 in chickens. Firstly, INHA expression increased and then decreased. The highest INHA mRNA abundance was found in the fifth largest preovulatory follicle (F5) (P < 0.01). In the prehierarchical follicles, INHA mRNA expression increased dramatically in small yellow follicles (SYF) (P < 0.01). Western blotting analysis showed that the INHA protein expression profile in the follicle was similar to its mRNA counterpart with greater expression in F5 and SYF follicles and lowest expression in F1 follicles (P < 0.05). These results suggest that INHA is a potential candidate gene improving reproductive traits in chickens.

How polymorphic markers contribute to genetic diseases in different populations? The study of inhibin A for premature ovarian insufficiency

OBJECTIVE

To verify the incidence of the G679A mutation in exon 2 of the gene inhibin alpha (INHA), in women with secondary amenorrhea and diagnosis of premature ovarian insufficiency, and in controls.

METHODS

A 5mL sample of peripheral blood was collected from all study participants in an EDTA tube and was used for DNA extraction. For the patient group, 5mL of blood were also collected in a tube containing heparin for karyotype, and 5mL were collected in a dry tube for follicle stimulant hormone dosage. All patient and control samples were initially submitted to analysis of the G679A variant in exon 2 of the INHA gene by PCR-RFLP technique. Samples from patients with premature ovarian insufficiency after PCR-RFLP were submitted to Sanger sequencing of the encoding exons 2 and 3. Sequencing was performed on ABI 3500 GeneticAnalyzer equipment and the results were evaluated by SeqA and Variant Reporter software.

RESULTS

Samples of 70 women with premature ovarian insufficiency and 97 fertile controls were evaluated. The G769A variant was found in only one patient in the Premature Ovarian Insufficiency Group and in no control, and it appears to be rare in Brazilian patients with premature ovarian insufficiency. This polymorphism was previously associated to premature ovarian insufficiency in several populations worldwide.

CONCLUSION

There is genetic heterogeneity regarding the INHA gene in different populations, and among the causes of premature ovarian insufficiency.

Genetics of the ovarian reserve

Primordial follicles or non-growing follicles (NGFs) are the functional unit of reproduction, each comprising a single germ cell surrounded by supporting somatic cells. NGFs constitute the ovarian reserve (OR), prerequisite for germ cell ovulation and the continuation of the species. The dynamics of the reserve is determined by the number of NGFs formed and their complex subsequent fates. During the reproductive lifespan, the OR progressively diminishes due to follicle atresia as well as recruitment, maturation, and ovulation. The depletion of the OR is the major determining driver of menopause, which ensues when the number of primordial follicles falls below a threshold of ∼1,000. Therefore, genes and processes involved in follicle dynamics are particularly important to understand the process of menopause, both in the typical reproductive lifespan and in conditions like primary ovarian insufficiency, defined as menopause before age 40. Genes and their variants that affect the timing of menopause thereby provide candidates for diagnosis of and intervention in problems of reproductive lifespan. We review the current knowledge of processes and genes involved in the development of the OR and in the dynamics of ovarian follicles.

Genetics of primary ovarian insufficiency: new developments and opportunities

BACKGROUND

Primary ovarian insufficiency (POI) is characterized by marked heterogeneity, but with a significant genetic contribution. Identifying exact causative genes has been challenging, with many discoveries not replicated. It is timely to take stock of the field, outlining the progress made, framing the controversies and anticipating future directions in elucidating the genetics of POI.

METHODS

A search for original articles published up to May 2015 was performed using PubMed and Google Scholar, identifying studies on the genetic etiology of POI. Studies were included if chromosomal analysis, candidate gene screening and a genome-wide study were conducted. Articles identified were restricted to English language full-text papers.

RESULTS

Chromosomal abnormalities have long been recognized as a frequent cause of POI, with a currently estimated prevalence of 10-13%. Using the traditional karyotype methodology, monosomy X, mosaicism, X chromosome deletions and rearrangements, X-autosome translocations, and isochromosomes have been detected. Based on candidate gene studies, single gene perturbations unequivocally having a deleterious effect in at least one population include Bone morphogenetic protein 15 (BMP15), Progesterone receptor membrane component 1 (PGRMC1), and Fragile X mental retardation 1 (FMR1) premutation on the X chromosome; Growth differentiation factor 9 (GDF9), Folliculogenesis specific bHLH transcription factor (FIGLA), Newborn ovary homeobox gene (NOBOX), Nuclear receptor subfamily 5, group A, member 1 (NR5A1) and Nanos homolog 3 (NANOS3) seem likely as well, but mostly being found in no more than 1-2% of a single population studied. Whole genome approaches have utilized genome-wide association studies (GWAS) to reveal loci not predicted on the basis of a candidate gene, but it remains difficult to locate causative genes and susceptible loci were not always replicated. Cytogenomic methods (array CGH) have identified other regions of interest but studies have not shown consistent results, the resolution of arrays has varied and replication is uncommon. Whole-exome sequencing in non-syndromic POI kindreds has only recently begun, revealing mutations in the Stromal antigen 3 (STAG3), Synaptonemal complex central element 1 (SYCE1), minichromosome maintenance complex component 8 and 9 (MCM8, MCM9) and ATP-dependent DNA helicase homolog (HFM1) genes. Given the slow progress in candidate-gene analysis and relatively small sample sizes available for GWAS, family-based whole exome and whole genome sequencing appear to be the most promising approaches for detecting potential genes responsible for POI.

CONCLUSION

Taken together, the cytogenetic, cytogenomic (array CGH) and exome sequencing approaches have revealed a genetic causation in ∼20-25% of POI cases. Uncovering the remainder of the causative genes will be facilitated not only by whole genome approaches involving larger cohorts in multiple populations but also incorporating environmental exposures and exploring signaling pathways in intragenic and intergenic regions that point to perturbations in regulatory genes and networks.

Murine Inhibin α-Subunit Haploinsufficiency Causes Transient Abnormalities in Prepubertal Testis Development Followed by Adult Testicular Decline

Activin production and signaling must be strictly regulated for normal testis development and function. Inhibins are potent activin inhibitors; mice lacking the inhibin-α gene (Inha-/- mice) cannot make inhibin and consequently have highly elevated activin and FSH serum concentrations and excessive activin signaling, resulting in somatic gonadal tumors and infertility. Dose-dependent effects of activin in testicular biology have been widely reported; hence, we hypothesized that male mice lacking one copy of the Inha gene would produce less inhibin and have an abnormal reproductive phenotype. To test this, we compared hormone concentrations, testis development, and sperm production in Inha+/+ and Inha+/- mice. Serum and testicular inhibin-α concentrations in adult Inha+/- mice were approximately 33% lower than wild type, whereas activin A, activin B, FSH, LH, and T were normal. Sixteen-day-old Inha+/- mice had a mixed phenotype, with tubules containing extensive germ cell depletion juxtaposed to tubules with advanced Sertoli and germ cell development. This abnormal phenotype resolved by day 28. By 8 weeks, Inha+/- testes were 11% larger than wild type and supported 44% greater daily sperm production. By 26 weeks of age, Inha+/- testes had distinct abnormalities. Although still fertile, Inha+/- mice had a 27% reduction in spermatogenic efficiency, a greater proportion of S-phase Sertoli cells and lower Leydig cell CYP11A1 expression. This study is the first to identify an intratesticular role for inhibin/inhibin-α subunit, demonstrating that a threshold level of this protein is required for normal testis development and to sustain adult somatic testicular cell function.

Association of inhibin α gene promoter polymorphisms with risk of idiopathic primary ovarian insufficiency in Korean women

OBJECTIVE

The aim of this study was to investigate whether two polymorphisms in the promoter region of inhibin alpha (INHA) are associated with risk of idiopathic primary ovarian insufficiency (POI) in Korean women, which is a controversial topic.

STUDY DESIGN

We genotyped the INHA polymorphisms c.-16C>T (rs35118453) and c.-124A>G (rs11893842) of 136 POI patients and 225 controls in Korean women by polymerase chain reaction and restriction fragment length polymorphism analysis. We then compared differences in genotype and allele frequencies (AF) of the polymorphisms between the two groups to determine odds ratios (OR) and 95% confidence intervals (CI) as measures of the strength of association between genotype and POI.

RESULTS

There were no significant differences in genotype or AF of the polymorphisms between the POI patients and controls. Haplotype analysis revealed that the T-G haplotype of the two variant alleles was more frequent in POI patients than in the controls (OR=1.630, 95% CI=1.081-2.457). Combination genotype analysis showed that the CT+TT/GG genotype frequency was higher in POI patients than in the controls (OR=2.414, 95% CI=1.190-4.895).

CONCLUSIONS

We provide evidence to suggest that when the two variant alleles are combined, the c.-16C>T and c.-124A>G polymorphisms are associated with increased POI risk in Korean women. We postulate that interactions between the INHA polymorphisms may affect POI risk.

Genomic markers of ovarian reserve

Ovarian reserve and its utilization, over a reproductive life span, are determined by genetic, epigenetic, and environmental factors. The establishment of the primordial follicle pool and the rate of primordial follicle activation have been under intense study to determine genetic factors that affect reproductive lifespan. Much has been learned from transgenic animal models about the developmental origins of the primordial follicle pool and mechanisms that lead to primordial follicle activation, folliculogenesis, and the maturation of a single oocyte with each menstrual cycle. Recent genome-wide association studies on the age of human menopause have identified approximately 20 loci, and shown the importance of factors involved in double-strand break repair and immunology. Studies to date from animal models and humans show that many genes determine ovarian aging, and that there is no single dominant allele yet responsible for depletion of the ovarian reserve. Personalized genomic approaches will need to take into account the high degree of genetic heterogeneity, family pedigree, and functional data of the genes critical at various stages of ovarian development to predict women's reproductive life span.

Mutations in inhibin and activin genes associated with human disease

Inhibins and activins are members of the transforming growth factor (TGFβ) superfamily, that includes the TGFβs, inhibins and activins, bone morphogenetic proteins (BMPs) and growth and differentiation factors (GDFs). The family members are expressed throughout the human body, and are involved in the regulation of a range of important functions. The precise regulation of the TGFβ pathways is critical, and mutations of individual molecules or even minor alterations of signalling will have a significant affect on function, that may lead to development of disease or predisposition to the development of disease. The inhibins and activins regulate aspects of the male and female reproductive system, therefore, it is not surprising that most of the diseases associated with abnormalities of the inhibin and activin genes are focused on reproductive disorders and reproductive cancers. In this review, I highlight the role of genetic variants in the development of conditions such as premature ovarian failure, pre-eclampsia, and various reproductive cancers. Given the recent advances in human genetic research, such as genome wide association studies and next generation sequencing, it is likely that inhibins and activins will be shown to play more important roles in a range of human genetic diseases in the future.

Exploring polymorphisms and their effects on reproductive traits of the INHA and INHβA genes in three goat breeds

In this study, we report the analysis of INHA and INHβA gene polymorphisms in 786 goats of three breeds: Xinong Saanen (SN), Guanzhong (GZ) and Boer (BG). We identified three new allelic variants: P1-C80G and/126G (GenBank accession no. HQ202573) in the three goat breeds and P2-C936T (GenBank accession no. HQ202572) in SN and GZ goat breeds. At P1 locus, AA, AB and BB genotypes were found in the three goat breeds. At P2 locus, CC and CT genotypes were found in SN and GZ goat breeds. After comparing genotype distribution within the three goat breeds, BG had conspicuous differences from SN and GZ (P < 0.001) at P2 locus. The SNP locus was in Hardy-Weinberg disequilibrium at P1 locus in the three goat breeds (P < 0.05). At P2 locus, the SNP locus was in Hardy-Weinberg disequilibrium in SN and GZ goat breeds (P < 0.05). Association of polymorphisms with litter size was done at P1 locus in the three goat breeds. The result showed that AA genotype had remarkable litter size at P1 locus in the three goat breeds (P < 0.05). Therefore, these results suggest that INHA gene is a strong candidate gene that affects litter size in goats.

Genetic defects of ovarian TGF-β-like factors and premature ovarian failure

Premature ovarian failure (POF) is an ovarian defect characterized by the premature depletion of ovarian follicles; POF affects approximately 1-2% of women under the age of 40 yr, thus representing one major cause of female infertility. POF relevance is continuously growing because women tend to conceive always more frequently beyond 30 yr. Frequently, POF is the end-stage of an occult process [primary ovarian insufficiency (POI)]. POI is a heterogeneous disease caused by a variety of mechanisms. Though the underlying cause remains unexplained in the majority of cases, several data indicate that POI has a strong genetic component. These data include the existence of several causal genetic defects in human, experimental, and natural models, as well as the frequent familiarity. The candidate genes are numerous, but POF remains unexplained in most of the cases. Several recent evidences have driven the attention of researchers on the possible involvement of various elements belonging to the transforming growth factor β family, which includes bone morphogenetic proteins, growth/differentiation factors, and inhibins. These peptides are produced by either the oocyte or granulosa cells to constitute a complex paracrine network within the ovarian follicle. Here, we review the studies reporting the genetic alterations of these factors in human and animal defects of ovarian folliculogenesis which support the fundamental roles played by these signals in ovarian morphogenesis and function.

Genetic aspects of premature ovarian failure: a literature review

BACKGROUND

The diagnosis of premature ovarian failure (POF) is based on the finding of amenorrhea before the age of 40 years associated with follicle-stimulating hormone levels in the menopausal range. It is a heterogeneous disorder affecting approximately 1% of women <40 years, 1:10,000 women by age 20 years and 1:1,000 women by age 30 years. POF is generally characterized by low levels of gonadal hormones (estrogens and inhibins) and high levels of gonadotropins (LH and FSH) (hypergonadotropic amenorrhea).

METHODS

Review of significant articles regarding genetic causes that are associated with POF.

RESULTS

Heterogeneity of POF is reflected by a variety of possible causes, including autoimmunity, toxics, drugs, as well as genetic defects. Changes at a single autosomal locus and many X-linked loci have been implicated in women with POF. X chromosome abnormalities (e.g., Turner syndrome) represent the major cause of primary amenorrhea associated with ovarian dysgenesis. Many genes have been involved in POF development, among them BMP15, FMR1, FMR2, LHR, FSHR, INHA, FOXL2, FOXO3, ERα, SF1, ERβ and CYP19A1 genes.

CONCLUSION

Despite the description of several candidate genes, the cause of POF remains undetermined in the vast majority of cases.

Analysis of cyclin-dependent kinase inhibitor 1B mutation in Han Chinese women with premature ovarian failure

The gene for cyclin-dependent kinase inhibitor 1B (CDKN1B; also known as P27(KIP1) and P27) encodes a cyclin-dependent kinase inhibitor and controls ovarian development in mice. In p27-deficient (p27(-/-)) mice, the overactivated follicular pool in ovaries was largely depleted, causing premature ovarian failure. The goal of this research was to investigate whether there are nucleotide changes in the CDKN1B gene of Han Chinese women with premature ovarian failure, as compared with control volunteers using candidate gene sequencing. No novel variations were found in exons encoding for CDKN1B. So the mutations in CDKN1B are not common with premature ovarian failure in Han Chinese women.

Inhibin and premature ovarian failure

BACKGROUND

Elucidation of the causes of premature ovarian failure (POF) is difficult due to the heterogeneity of the condition. Inhibin is a potential candidate gene for POF based on its dual actions on FSH secretion by the pituitary and gametogenesis in the gonads. A missense mutation in the inhibin alpha subunit gene (INHA G769A) is associated with POF in several populations. However, there is phenotypic heterogeneity in INHA G769A mutation carriers.

METHODS

Relevant studies were identified by searching PubMed and mutational frequencies combined for meta-analysis.

RESULTS

Meta-analysis of published studies revealed a risk difference of 0.04 (-0.030 to 0.11). The occurrence of asymptomatic carriers in populations suggests incomplete penetrance and/or a multi-genetic cause of POF. We propose that a decline in inhibin bioactivity caused by the mutation could increase FSH levels; and in a susceptible individual, the heightened sensitivity to gonadotrophins causes POF. Impaired paracrine effects of inhibin could impact folliculogenesis due to reduced antagonism of activin, bone morphogenetic protein 15 and growth differentiation factor 9. Functional studies of this mutation indicate normal production of dimeric inhibin A and B and impaired bioactivity of inhibin B.

CONCLUSIONS

The identification of an autosomal mutation in the inhibin alpha subunit gene that is significantly linked to POF in certain ethnic populations highlights the role of inhibin in the regulation of ovarian biology and fertility. Although the reduction of inhibin B bioactivity by the INHA G769A mutation is clearly not the only cause, evidence suggests that this change may serve as a susceptibility factor, increasing the likelihood of POF.

Genetically modified mouse models for premature ovarian failure (POF)

Premature ovarian failure (POF) is a complex disorder that affects approximately 1% of women. POF is characterized by the depletion of functional ovarian follicles before the age of 40 years, and clinically, patients may present with primary amenorrhea or secondary amenorrhea. Although some genes have been hypothesized to be candidates responsible for POF, the etiology of most of the cases is idiopathic, with the underlying causes still unidentified because of the heterogeneity of the disease. In this review, we consider some mutant mouse models that exhibit phenotypes which are comparable to human POF, and we suggest that the use of these mouse models may help us to gain a better understanding of the molecular mechanisms underlying POF in humans.

Systematic analysis, comparison, and integration of disease based human genetic association data and mouse genetic phenotypic information

Background

The genetic contributions to human common disorders and mouse genetic models of disease are complex and often overlapping. In common human diseases, unlike classical Mendelian disorders, genetic factors generally have small effect sizes, are multifactorial, and are highly pleiotropic. Likewise, mouse genetic models of disease often have pleiotropic and overlapping phenotypes. Moreover, phenotypic descriptions in the literature in both human and mouse are often poorly characterized and difficult to compare directly.

Methods

In this report, human genetic association results from the literature are summarized with regard to replication, disease phenotype, and gene specific results; and organized in the context of a systematic disease ontology. Similarly summarized mouse genetic disease models are organized within the Mammalian Phenotype ontology. Human and mouse disease and phenotype based gene sets are identified. These disease gene sets are then compared individually and in large groups through dendrogram analysis and hierarchical clustering analysis.

Results

Human disease and mouse phenotype gene sets are shown to group into disease and phenotypically relevant groups at both a coarse and fine level based on gene sharing.

Conclusion

This analysis provides a systematic and global perspective on the genetics of common human disease as compared to itself and in the context of mouse genetic models of disease.

Mutational analysis of SAL-Like 4 (SALL4) in Han Chinese women with premature ovarian failure

Pluripotency associated transcription factor, SAL-Like 4 (SALL4), might play an important role in conferring totipotency on oocytes. In the present study, we screened SALL4 coding regions for mutations in 100 Han Chinese women with non-syndromic ovarian failure and discovered two novel non-synonymous variants in the SALL4 gene: c.541G>A (p.Val181Met) and c.2449A>G. (p.Thr817Ala). The former variant was located in an evolutionary conserved region of SALL4 protein and might affect its function. This is the first report to suggest that SALL4 might be a potential candidate gene of premature ovarian failure.

A challenge to the menopause stereotype: young Australian women's reflections of 'being diagnosed' as menopausal

This paper reports on a qualitative study designed to examine (i) possible explanations for difficulties young Australian women (under 40 years) encountered in the process of gaining a diagnosis of premature menopause and (ii) to address issues underpinning this aspect of menopause. Drawing on hermeneutic phenomenology, face-to-face interviews were carried out with 35 women who consented to share their experiences of 'being diagnosed' with premature menopause. The participants responded to an advertisement in a newspaper article, a radio announcement or through a menopause support centre. While all participants were located in Australia, larger numbers were from the metropolitan areas of Sydney, New South Wales, and Perth, Western Australia. This research reports that the process of finding an explanation for the physical and emotional symptoms the women were experiencing was very complex. The findings varied regarding the psychological and physical symptoms experienced, described feelings, and reasons that led to a diagnosis of menopause. This paper suggests that the age of the women and the non-specific symptoms experienced by them contributed significantly to the delay and uncertainty surrounding the experience of being diagnosed with premature menopause. There was uncertainty of the origin of symptoms, which led the women to feel as though they were 'going insane' or that it was 'all in their heads'. This frequently led to symptoms of menopause being attributed (by health professionals) to a psychiatric basis and menopause being overlooked for varying lengths of time.

Investigating the association between inhibin alpha gene promoter polymorphisms and premature ovarian failure

OBJECTIVE

To determine whether variants in the promoter region of the inhibin alpha gene (INHA) are associated with premature ovarian failure (POF).

DESIGN

Mutational analysis of the INHA gene promoter in women with POF.

SETTING

Academic institution.

PATIENT(S)

Patients with POF (n = 194) and controls (n = 162) from New Zealand and Slovenia.

INTERVENTION(S)

Peripheral blood samples were screened for known polymorphisms in the INHA promoter (c.-16C-->T, c.-124A-->G, and an imperfect TG repeat at approximately -300 base pairs). Genotyping was performed by restriction fragment length polymorphism, forced restriction fragment length polymorphism, and nondenaturing high-performance liquid chromatography analysis.

MAIN OUTCOME MEASURE(S)

Genotypic status of INHA promoter polymorphisms.

RESULT(S)

Significant differences in INHA promoter allele frequencies were observed between POF patient populations and controls. Significant reductions in allele frequency were observed for the -16T allele (New Zealand POF) and -124G allele (total POF) and for INHA promoter haplotypes C (New Zealand POF) and D (Slovenian POF).

CONCLUSION(S)

We conclude that INHA promoter variants are associated with the development of POF.

Recent advances in the study of genes involved in non-syndromic premature ovarian failure

Premature ovarian failure (POF) is a common pathology leading to infertility affecting about 1% of women under 40 years old. In POF patients, the ovarian dysfunction is characterized by the lack of the ovarian response to close a negative feedback loop on the synthesis of pituitary gonadotropins. Although the majority of cases are considered as idiopathic, diverse aetiologies have been associated, including genetic factors. Up to now, the potential genetic causes of non-syndromic POF have been established mainly by genetic linkage analysis of familial cases or by the screening of mutations in candidate genes based on animal models. Here, we review recent advances in the study of candidate genes.

Genetic investigation of four meiotic genes in women with premature ovarian failure

OBJECTIVE

The goal of this study was to determine whether mutations of meiotic genes, such as disrupted meiotic cDNA (DMC1), MutS homolog (MSH4), MSH5, and S. cerevisiae homolog (SPO11), were associated with premature ovarian failure (POF).

DESIGN

Case-control study.

METHODS

Blood sampling, karyotype, hormonal dosage, ultrasound, and ovarian biopsy were carried out on most patients. However, the main outcome measure was the sequencing of genomic DNA from peripheral blood samples of 41 women with POF and 36 fertile women (controls).

RESULTS

A single heterozygous missense mutation, substitution of a cytosine residue with thymidine in exon 2 of MSH5, was found in two Caucasian women in whom POF developed at 18 and 36 years of age. This mutation resulted in replacement of a non-polar amino acid (proline) with a polar amino acid (serine) at position 29 (P29S). Neither 36 control women nor 39 other patients with POF possessed this genetic perturbation. Another POF patient of African origin showed a homozygous nucleotide change in the tenth of DMC1 gene that led to an alteration of the amino acid composition of the protein (M200V).

CONCLUSIONS

The symptoms of infertility observed in the DMC1 homozygote mutation carrier and in both patients with a heterozygous substitution in exon 2 of the MSH5 gene provide indirect evidence of the role of genes involved in meiotic recombination in the regulation of ovarian function. MSH5 and DMC1 mutations may be one explanation for POF, albeit uncommon.

Autoimmunity and premature ovarian failure

PURPOSE OF REVIEW

The different patterns of autoreactivity that may account for the premature infertility observed in patients with premature ovarian failure are described.

RECENT FINDINGS

Animal model studies have detailed fundamental immune dysregulatory patterns that induce ovarian failure in the context of global polyglandular involvement, as well as autoimmune mechanisms that induce ovarian failure in the context of targeted ovarian pathology. Recent studies on premature ovarian failure patients implicate the ubiquitously expressed glycolytic enzyme, alpha-enolase, as a potential antigenic target, particularly in those patients with polyglandular involvement; and the ovarian-specific maternal-effect protein, Mater, whose expression is essential for fertility.

SUMMARY

Several fundamentally distinct mechanisms may account for premature ovarian failure, including global immune dysregulation, particularly in patients with polyglandular autoimmunity. Premature ovarian failure may also be due to inflammatory autoimmunity targeted to ovarian-specific germline antigens (e.g., zona pellucida proteins or Mater) or differentiation/regulatory factors (e.g., inhibin-alpha). Moreover, the ovarian autoimmunity may be mediated by T cells (e.g., those targeting zona pellucida proteins) or B cells/antibodies (e.g., those targeting inhibin-alpha). Thus premature ovarian failure appears to be a complex disease entity with multiple underlying etiopathogenic contributions including the possibility of several distinctly different autoimmune mechanisms.

Analysis of LHX8 mutation in premature ovarian failure

The LHX8 (LIM homeobox 8) gene encodes a LIM homeodomain transcriptional regulator that is preferentially expressed in germ cells and critical for mammalian oogenesis. The authors investigated whether nucleotide changes were present in the LHX8 gene of Caucasian women with premature ovarian failure (POF), as compared with control women. When the authors sequenced 95 Caucasian women with POF, they discovered two novel single-nucleotide polymorphisms (SNPs) in intron 3 (c.769+10G>T) and 3' untranslated region (c.1787A>G) of the LHX8 gene. These polymorphisms also were found in controls (n = 94), at frequencies that were not statistically different from those in POF women. Mutations in the LHX8 exons are uncommon in Caucasian women with POF.

Branched chain alpha-keto acid dehydrogenase, E1-beta subunit gene is associated with premature ovarian failure

Genetic variants of the human branched chain alpha-keto acid dehydrogenase, E1-beta subunit (BCKDHB) gene were identified and they have been associated with premature ovarian failure (POF). Reconstructed haplotype from these variants was also associated with POF.

Mutation analysis of NANOS3 in 80 Chinese and 88 Caucasian women with premature ovarian failure

NANOS3 encodes an RNA-binding protein and has a conserved function in germ cell development. Our objective was to investigate whether mutations in NANOS3 were present in Chinese and Caucasian women with premature ovarian failure. A known synonymous single-nucleotide polymorphism (rs 2016163) in exon 1 was identified through sequencing 80 Chinese and 88 Caucasian women with premature ovarian failure. No additional single-nucleotide polymorphisms or mutations were found in exons encoding for NANOS3. Our findings suggest that mutations in NANOS3 exons are rare in both Chinese and Caucasian women with premature ovarian failure.

L’insuffisance ovarienne prématurée

Premature ovarian failure (POF) is defined by at least four months of amenorrhea with elevated gonadotropins (usually above 40 UI/L) detected on two occasions a few weeks apart, in a woman before the age of 40. It occurs in 1 out of 10,000 in women below the age of 20, 1/1,000 below 30 and 1% in women before the age of 40. In 80% of POF cases, the etiology is unknown, except for Turner syndrome. The different etiologies identified are 1) iatrogenic following chemotherapy and/or radiotherapy, 2) autoimmune, 3) viral, 4) genetic (RFSH, FOXL2, FRAXA, BMP15, GDF9, GALT, 17 hydroxylase...). Management of these patients includes hormone replacement therapy in order to avoid an increase in cardiovascular risk and osteoporosis related to hypoestrogenism. Infertility is common, as only 3 to 10% of the patients will have natural conception. When fertility is desired, women with POF should be oriented towards oocyte donation centers. Research is currently performed in order to identify new genes involved in POF.

Autoimmune targeted disruption of the pituitary-ovarian axis causes premature ovarian failure

Premature ovarian failure (POF) is characterized by amenorrhea and high serum levels of follicle-stimulating hormone (FSH). POF causes female infertility and represents a substantial women's health risk affecting 1% of women by age 40. Although ovarian autoimmunity has been associated with POF, the identity of ovarian Ags recognized is unknown. In this study, we show that autoimmune-targeted disruption of the pituitary-ovarian axis leads to POF. Immunization of SWXJ female mice with the p215-234 peptide derived from mouse inhibin-alpha activates CD4(+) T cells and induces experimental autoimmune oophoritis with a unique biphasic phenotype characterized by an early stage of enhanced fertility followed by a delayed stage of POF. Affected mice show high serum levels of inhibin-alpha-neutralizing Abs that prevent inhibin-mediated down-regulation of activin-induced pituitary FSH release. The loss of activin/FSH down-regulation leads to prolonged metestrus-diestrus, superovulation, increased numbers of mature follicles, increased offspring, accelerated depletion of primordial follicles, and ultimately premature infertility. Thus, inhibin-alpha-targeted experimental autoimmune oophoritis is initiated by CD4(+) Th1 T cells that stimulate B cells to produce inhibin-alpha-neutralizing Abs directly capable of mediating POF and transferring disease into naive recipients. Our inhibin-alpha autoimmune model of POF shows how premature infertility may develop in the context of elevated FSH levels thereby closely mimicking the hallmark features of human POF.

The genetic basis of premature ovarian failure

Premature ovarian failure (POF) is a common condition, affecting approximately 1:100 women. It is characterised by amenorrhea, hypoestrogenism, and elevated gonadotrophin levels in women under the age of 40. It is often an unexpected and distressing diagnosis, which coincides with infertility and menopausal symptoms. There is a well recognised genetic basis to the development of POF. Our laboratory has identified several candidate genes associated with POF.