Controversial role of inhibin α-subunit gene in the aetiology of premature ovarian failure

NR5A1/SF-1 Collaborates with Inhibin α and the Androgen Receptor

Steroidogenic factor 1 (SF-1) is a nuclear receptor that regulates steroidogenesis and reproductive development. NR5A1/SF-1 variants are associated with a broad spectrum of phenotypes across individuals with disorders of sex development (DSDs). Oligogenic inheritance has been suggested as an explanation. SF-1 interacts with numerous partners. Here, we investigated a constellation of gene variants identified in a 46,XY severely undervirilized individual carrying an ACMG-categorized 'pathogenic' NR5A1/SF-1 variant in comparison to the healthy carrier father. Candidate genes were revealed by whole exome sequencing, and pathogenicity was predicted by different in silico tools. We found variants in NR1H2 and INHA associated with steroidogenesis, sex development, and reproduction. The identified variants were tested in cell models. Novel SF-1 and NR1H2 binding sites in the AR and INHA gene promoters were found. Transactivation studies showed that wild-type NR5A1/SF-1 regulates INHA and AR gene expression, while the NR5A1/SF-1 variant had decreased transcriptional activity. NR1H2 was found to regulate AR gene transcription; however, the NR1H2 variant showed normal activity. This study expands the NR5A1/SF-1 network of interacting partners, while not solving the exact interplay of different variants that might be involved in revealing the observed DSD phenotype. It also illustrates that understanding complex genetics in DSDs is challenging.

Association of Polymorphisms in FSHR, ESR1, and BMP15 with Primary Ovarian Insufficiency and Meta-Analysis

Primary ovarian insufficiency (POI) can lead to menstrual disturbance, resulting in ovarian dysfunction before age 40. Prevalence of POI is usually less than 1%; however, ethnicity or population characteristics may affect prevalence. POI is a heterogeneous disease that results from abnormalities in immunological and hormonal factors. Genetic factors can also contribute to POI. Here, we examine FSHR, ESR1, and BMP15 polymorphisms in patients with POI, and controls. We examined a hormonal gene that is important for pregnancy, follicle-stimulating hormone receptor (FSHR), as well as estrogen receptor 1 (ESR1), and associated it with FSHR expression, ovulation rate, and bone morphogenetic protein 15 (BMP15). We examined 139 Korean patients under age 40 with POI, and 350 Korean control participants without POI. Genotyping was performed by a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and TaqMan assays. Each identified genotype was subjected to statistical analysis to determine the odds ratios (ORs) and 95% confidence intervals (CIs). In combination genotype analyses, FSHR rs6165 A > G combined with ESR1 rs9340799 A > G, AG/GG (OR: 5.693; 95% CI: 1.088-29.792), as well as FSHR rs6166 A > G combined with ESR1 rs9340799 C > T, AG/GG (OR: 5.940; 95% CI: 1.134-31.131), were significantly associated with POI prevalence. Furthermore, an FSHR rs6165 A > G and BMP rs17003221 C > T, AG/CC combination was associated with POI prevalence (OR: 1.874; 95% CI: (1.059-3.316; p-value: 0.031)). In meta-analysis, FSHR rs6165 AA vs. AG + GG is associated with POI (p = 0.0013), and ESR1 rs2234693 AA vs. AG + GG is also associated with POI (p = 0.0101). Here, we compared the genotypes of FSHR, ESR1, and BMP15 in patients with POI, and controls. We found significant differences in genotype combinations between polymorphisms in FSHR and other genes. Through meta-analysis, we found that ESR1 rs9340799 and rs2234693 are associated with POI prevalence, and that BMP15 rs17003221 increases POI risk. These findings help to improve POI diagnosis in Korean women.

Methylation and mutation of the inhibin‑α gene in human melanoma cells and regulation of PTEN expression and AKT/PI3K signaling by a demethylating agent

Inhibin suppresses the pituitary secretion of follicle‑stimulating hormone and has been reported to act as a tumor suppressor gene in the gonad in mice. Epigenetic modifications, mutations, changes in the loss of heterozygosity (LOH) of the inhibin‑α gene and regulation of gene expression in response to a demethylating agent [5‑aza‑2'‑deoxycytidine (5‑Aza‑dC)] in human melanoma cells were assessed. In addition, the association between a mutation in the 5'‑untranslated region (5'‑UTR) of the inhibin‑α subunit and the expression of phosphatidylinositol 3,4,5‑trisphosphate‑dependent Rac exchanger 2 (PREX2) and phosphatase and tensin homolog (PTEN) as well as AKT/PI3K signaling was determined. The methylation status of the CpG sites of the inhibin‑α promoter was analyzed by methylation‑specific PCR in bisulfite‑treated DNA. Cell viability was counted using the trypan blue assay, mRNA expression was examined via reverse transcription‑quantitative PCR, and protein expression was examined via western blot analysis. The inhibin‑α promoter was hypermethylated in G361, SK‑MEL‑3, SK‑MEL‑24 and SK‑MEL‑28 cells and moderately methylated in SK‑MEL‑5 cells. Inhibin‑α gene mutations were observed in the 5'‑UTR exon 1 of G361, SK‑MEL‑5, SK‑MEL‑24 and SK‑MEL‑28 cells as well as in exon 2 of SK‑MEL‑3 cells. Allelic imbalance, including LOH, in the inhibin‑α gene was detected in human melanoma cells. Treatment with 5‑Aza‑dC increased inhibin‑α mRNA and protein levels, inhibited cell proliferation, and delayed the doubling times of surviving melanoma cells. In 5‑Aza‑dC‑treated cells, PREX2 protein expression was slightly increased in G361 and SK‑MEL‑24 cells and decreased in SK‑MEL3, SK‑MEL‑5 and SK‑MEL‑28 cells. However, the protein expression of PTEN was decreased in melanoma cells. In addition, AKT and PI3K protein phosphorylation levels increased in all melanoma cells, except of G361 cells, demonstrating decreased PI3K protein phosphorylation. These data provided evidence that methylation, mutation and LOH are observed in the inhibin α‑subunit gene and gene locus in human melanoma cells. Furthermore, the demethylating agent reactivated inhibin‑α gene expression and regulated PREX2 expression. AKT/PI3K signaling increased as PTEN expression decreased. In addition, mutations in the tumor suppressor inhibin‑α, PTEN and p53 genes were not associated with transcriptional silencing, gene expression and cell growth as analyzed through experiments and literature reviews. These data demonstrated that methylation and mutations were associated with the inhibin‑α gene in human melanoma cells and indicated the regulation of PTEN expression and AKT/PI3K signaling by a demethylating agent.

Variations in the inhibin gene in Kashmiri women with primary ovarian insufficiency

Inhibin is a glycoprotein produced by granulosa cells and its main function is the negative feedback control of follicle stimulating hormone (FSH) which has an important role in folliculogenesis. Mutation in the INHα gene leading to decreased bioactive inhibin has been associated with primary ovarian insufficiency (POI). The aim of this study was to investigate the role of variations in the INHα gene in increasing the susceptibility to POI in Kashmiri women. INHα c.769G > A mutation was analysed in 100 POI cases and 100 controls using PCR-RFLP and agarose gel electrophoresis. The INHα c.769G > A mutation was found in 10% of POI cases with 8% having heterozygous mutation and 2% having a homozygous mutation. The frequency of mutation in healthy controls was zero. Statistically, a very significant association was found between INHα c.769G > A mutation and the occurrence of POI (p = 0.0015). Moreover, the mutation was also significantly associated with high levels of FSH in POI patients (p < 0.0001). Given the significant association of INHα c.769G > A mutation with the increased FSH levels and POI in Kashmiri population, we suggest this mutation can be used to identify POI variants for screening of women susceptible to POI before the disease onset and can further facilitate putative therapy for such patients.

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.

Distribution of FMR1 and FMR2 Repeats in Argentinean Patients with Primary Ovarian Insufficiency

The premutation state of FMR1 (Fragile X Mental Retardation 1) has been associated with primary ovarian insufficiency (POI), and is the most common known genetic cause for 46,XX patients. Nevertheless, very few studies have analyzed its frequency in Latin American populations. Additionally, a relationship between alleles carrying a cryptic microdeletion in the 5’UTR of FMR2 and the onset of POI has only been studied in one population. Our aim was to analyze the incidence of FMR1 premutations and putative microdeletions in exon 1 of FMR2 in a cohort of Argentinean women with POI. We studied 133 patients and 84 controls. Fluorescent PCR was performed, and the FMR2 exon 1 was further sequenced in samples presenting less than 11 repeats. We found the frequency of FMR1 premutations to be 6.7% and 2.9% for familial and sporadic patients, respectively. Among controls, 1/84 women presented a premutation. In addition, although we did not find microdeletions in FMR2, we observed a change (T >C) adjacent to the repeats in two sisters with POI. Given the repetitive nature of the sequence involved, we could not ascertain whether this represents a single nucleotide polymorphism (SNP) or a deletion. Therefore, a relationship between FMR2 and POI could not be established for our population.

Inhibin-α gene mutations and mRNA levels in human lymphoid and myeloid leukemia cells

The inhibin-α gene was identified as a tumor suppressor gene in the gonads and adrenal glands by functional studies using knockout mice. Methylation of CpG sites within the regulatory regions of tumor suppressor gene is frequently associated with their transcriptional silencing. We investigated epigenetic modifications, changes in loss of heterozygosity (LOH), and mutation of the inhibin-α gene, and regulation of transcriptional expression in response to inhibitors of DNA methylation (5-aza-2'-deoxycytidine, 5-AzaC) in human lymphoid (Jurkat, Molt-4, Raji, and IM-9) and myeloid (HL-60, Kasumi-1, and K562) leukemia cells. The inhibin-α promoter was hypermethylated in lymphoid (Molt-4 and Raji) and myeloid (HL-60 and Kasumi-1) leukemia cells. Inhibin-α gene mutations differed significantly between lymphoid (heterozygote) and myeloid (homozygote) leukemia cells. LOH in the inhibin-α gene was detected in lymphoid and myeloid leukemia cells, with the exception of Jurkat cells. Treatment with 5-AzaC, a demethylating agent, resulted in increased inhibin-α mRNA and protein levels in most of the cell lines. Also, 5-AzaC treatment inhibited cell proliferation and induced apoptosis. Taken together, our results reveal that the inhibin-α gene is transcriptionally silenced in human leukemia cells and that reactivation is suppressed by a demethylating agent. In addition, mutations in, and expression levels of, the inhibin-α gene differed between human lymphoid and myeloid leukemia cells.

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.

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.

Transcriptional silencing of the inhibin-α gene in human gastric carcinoma cells

Although inhibin was first identified as a hormone regulating pituitary FSH secretion, it was later recognized to act as a tumor suppressor in the gonad and adrenal glands. Recently, the alpha subunit of this dimeric hormone (inhibin‑α) was reported to be involved in prostate tumorigenesis. To identify additional roles outside the reproductive axis, we investigated inhibin‑α gene activity and subsequent cell fate in human gastric cancer cells. The results were as follows: all the gastric cancer cells had at least one of a set of abnormalities including hypermethylation of the promoter, mutation of the 5'‑UTR or allelic imbalance including LOH in the inhibin‑α gene. Hypermethylation of the promoter and mutation of the 5'‑UTR in inhibin‑α were observed in SNU‑1, SNU‑5 and SNU‑484 cells. LOH was observed in AGS, KATO III, SNU‑5, SNU‑484 and SNU‑668 cells. Treatment with 5‑AzaC, a demethylating agent, induced demethylation of the inhibin‑α promoter in the SNU‑1, SNU‑5 and SNU‑484 cell lines, with the CpG5 site being strongly influenced by 5‑AzaC. In addition, inhibin‑α mRNA and protein were maintained at low levels in most of the gastric cancer cell lines. These low levels of mRNA and protein expression could be increased in most lines by treatment with 5‑AzaC. These increased inhibin‑α expression levels seemed to be closely associated with apoptosis and suppression of cell growth. Taken together, our results reveal that the inhibin‑α gene is transcriptionally silenced in human gastric cancer cells, and that reactivation of the gene suppresses their growth characteristics. This suggests that inhibin‑α may have a more general tumor suppressor activity outside the reproductive axis.

LAMC1 gene is associated with premature ovarian failure

OBJECTIVES

Common variations with modest effect in complex and polygenic disease such as premature ovarian failure (POF) can be detected by a genome wide association study. We performed a genome wide association study to identify predisposing genes associated with an increased risk of POF.

STUDY DESIGN

In stage I, genome wide association study was performed using 24 POF patients and 24 matched controls. A strongly associated region was re-tested to confirm the association with POF in stage II using 98 patients and 218 matched controls.

RESULTS

In the stage I, we found a strongly associated region that was located on chromosome 1q31 and encoded the laminin gamma 1 (LAMC1) gene. All 22 single nucleotide polymorphisms (SNPs) in the LAMC1 formed a linkage disequilibrium block and two haplotypes were significantly associated with POF. In the stage II, 14 SNPs, the majority of which were SNPs located in coding region and tagging SNPs, were genotyped. Distributions of 9 SNPs of them including one nonsynonymous SNP (rs20558) and one haplotype (HT1, C-C-T-G-C-C-A-T-T-C) were significantly higher in POF patients than in control group (86.6% and 74.5%, respectively, OR=2.209, CI: 1.139-4.284, P=0.017).

CONCLUSIONS

We showed for the first time that LAMC1 is significantly associated with POF, and specifically, possession of at least one HT1 was associated with susceptibility to POF. This result means that HT1 may co-exist with causative variant for susceptibility to POF in linkage disequilibrium and that the LAMC1 may be involved in POF pathogenesis.

Relationship between inhibin-α gene polymorphisms and premature ovarian failure in Korean women

OBJECTIVE

The aim of this study was to determine the relationship between inhibin-α (INHα) gene polymorphisms and the prevalence of premature ovarian failure (POF) in Korean women.

METHODS

The INHα -124A/G, -16C/T, 679G/A, and 769G/A polymorphisms were analyzed in 52 women with POF and 55 normal healthy women using polymerase chain reaction-restriction enzyme fragment length polymorphism analysis.

RESULTS

The 679G/A and 769G/A polymorphisms were not observed. The frequencies of the C allele of the INHα -16C/T polymorphism and the G allele of the INHα -124A/G polymorphism were significantly lower in the women with POF than in the normal control women. The frequencies of the CG haplotype allele of these INHα -16C/T and -124A/G gene polymorphisms were also significantly lower in the women with POF than in the control women.

CONCLUSIONS

The INHα -16C/T and -124A/G polymorphisms are genetic factors associated with the prevalence of POF in Korean women.

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.

Chromosomal abnormalities in women with premature ovarian failure

Premature ovarian failure is a complex disorder that results in the early loss of ovarian function; however this disease must be separated from early menopause because these patients can sporadically ovulate and in literature are described pregnancies. The aetiology and the patho-physiology of premature ovarian failure are still matter of debate, but is commonly accepted that genetic factors play an important role. This review is aimed to present an overview of known inherited factor implied in the pathogenesis of this disorder to help physician in the counselling of affected pregnant women.

Mutational analysis of inhibin alpha gene revealed three novel variations in Indian women with premature ovarian failure

OBJECTIVE

To determine the prevalence of inhibin alpha gene variants in Indian women with premature ovarian failure.

DESIGN

Mutational analysis of DNA from patients and control subjects.

SETTING

Clinical genetics and molecular cytogenetic laboratory.

PATIENTS(S)

One hundred 46,XX women with premature ovarian failure and 50 healthy control subjects <40 years old.

INTERVENTION(S)

Blood samples were collected.

MAIN OUTCOME MEASURE(S)

Extraction of DNA from blood samples, amplification of inhibin alpha gene, restriction fragment length polymorphism (RFLP), and direct DNA sequencing.

RESULT(S)

The RFLP analysis revealed a 769G-->A missense inhibin alpha mutation. There were three inhibin alpha gene sequence variants that resulted in a change from 734 C-->A/Ala 245 Asp, 755 C-->A/Pro 252 His, and 777 C-->A/His 259 Gln by DNA sequencing.

CONCLUSION(S)

Variants in the inhibin alpha gene are strongly associated with premature ovarian failure in Indian patients.

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.

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.

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.

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.