[NR5A1 and ovarian failure]

In cases of familial primary ovarian insufficiency and disorders of gonadal development, consider NR5A1/SF-1 sequence variants

RESEARCH QUESTION

Primary ovarian insufficiency (POI) is defined as the early exhaustion of ovarian function, before the age of 40 years. Its origin is genetic in 20-25% of cases. In rare cases, sequence variants of the NR5A1/SF-1 gene may result in POI, or in various disorders of gonadal development (DGD) or adrenal insufficiency.

DESIGN

This study describes the cases of two families in which the association of DGD and POI enabled a diagnosis of NR5A1 deleterious variations. Their clinical, hormonal, ultrasound and genetic characteristics are reported.

RESULTS

The mothers of the affected children were 21 and 29 years when POI was diagnosed. Each nonetheless had two spontaneous pregnancies. The children have different phenotypes and different forms of DGD. None of the affected family members had adrenal insufficiency. A new sequence variant of the NR5A1 gene was identified in one family: p.Cys283Phe (c.848G>T), and the NR5A1 sequence variant c.86G>C was found in the other family.

CONCLUSION

Sequence variation of the NR5A1 gene is a possibility that must be considered when a woman with POI or a diminished ovarian reserve has a family member or child with DGD. If a variant is identified, genetic counselling is essential for the patient and his/her family.

Genetic Causes of Female Infertility

Nowadays, women's family planning intentions are postponed, and it is common that only later will the conditions be created for the woman to have children. Fortunately, in most cases, pregnancy is possible in this case, taking into account the increased genetic risk. However, this later childbirth may become impossible or significantly more difficult if we can detect sterility and infertility, and its genetic cause is revealed. Any procedure that can help to reduce the "aging" of society, the reproduction rate, must be treated as an important public health issue. It would be particularly important in cases where genetic causes can be detected in the background of female sterility and infertility. Endocrine causes, infections, immunological causes, psychic factors, stress, and weight problems may be among the causes of female infertility in addition to genetic causes and genetic developmental disorders. Infertility can also be caused by iatrogenic factors, previous interventions, and surgery. In this chapter we will discuss the diseases in which genetic factors play a role.

Array-CGH diagnosis in ovarian failure: identification of new molecular actors for ovarian physiology

Background

Ovarian failure (OF) is considered premature if it occurs before the age of 40.

This study investigates the genetic aetiology underlying OF in women under the age of 40 years.

Methods

We conducted an experimental prospective study performing all genome microarrays in 60 patients younger than 40 years presenting an OF revealed by a decrease of circulating Anti-Müllerian Hormone (AMH) and leading to an oocyte donation program.

Results

We identified nine significant copy number variations (CNVs) including candidate genes potentially implicated in reproductive function. These genes are principally involved in cell division and chromosome segregation (SYCE1, CLASP1, CENP-A, CDC16), in ciliary development and/or function (RSPH1, KIF24), are linked with known gonadal genes or expressed in female genital tract (CSMD1, SEMA6D, KIAA1324).

Conclusions

Our data strengthen the idea that microarrays should be used in combination with karyotype for aetiological assessment of patients with OF. This analysis may have a therapeutic impact as the identification of new molecular actors for gonadal development or ovarian physiology is useful for the prediction of an ovarian reserve decline and makes possible preventive fertility preservation.

[Ovarian failure: New treatments in perspective?]

The premature loss of ovarian function may have physical and psychological consequences. A better understanding of its mechanism is therefore needed. Because they are affecting the oocyte quality, the decline of the ovarian reserve and high maternal age are implicated in many defects leading to chromosomal defects, modifications of gene expression or alterations of the mitochondrial pattern of the oocyte. However, cellular therapies such as ovarian follicle activation or isolation of ovarian stem cells are promising treatments of ovarian failure.

Genetics of primary ovarian insufficiency: a review

Primary ovarian insufficiency is one of the main causes of female infertility owing to an abnormal ovarian reserve. Its relevance has increased in more recent years due to the fact that age of motherhood is being delayed in developed countries, with the risk of having either primary ovarian insufficiency or less chances of pregnancy when women consider the option of having their first baby. Several exogenous factors can lead to this event, such us viral infections, metabolomic dysfunction, autoimmune diseases, and environmental or iatrogenic factors, although in most cases the mechanism that leads to the disorder is unknown. Genetic factors represent the most commonly identified cause and the impact of sex chromosome abnormalities (e.g., Turner syndrome or X structural abnormalities), autosomal and X-linked mutations on the genesis of primary ovarian insufficiency has also been well described. Yet in most cases, the genetic origin remains unknown and there are multiple candidate genes. This review aims to collect all the genetic abnormalities and genes associated with syndromic and non syndromic primary ovarian insufficiency that have been published in the literature to date using the candidate-gene approach and a genome-wide analysis.

Analysis of the gene coding for steroidogenic factor 1 (SF1, NR5A1) in a cohort of 50 Egyptian patients with 46,XY disorders of sex development

OBJECTIVE

Steroidogenic factor 1 (SF1, NR5A1) is a key transcriptional regulator of genes involved in the hypothalamic-pituitary-gonadal axis. Recently, SF1 mutations were found to be a frequent cause of 46,XY disorders of sex development (DSD) in humans. We investigate the frequency of NR5A1 mutations in an Egyptian cohort of XY DSD.

DESIGN

Clinical assessment, endocrine evaluation and genetic analysis of 50 Egyptian XY DSD patients (without adrenal insufficiency) with a wide phenotypic spectrum.

METHODS

Molecular analysis of NR5A1 gene by direct sequencing followed by in vitro functional analysis of the two novel missense mutations detected.

RESULTS

Three novel heterozygous mutations of the coding region in patients with hypospadias were detected. p.Glu121AlafsX25 results in severely truncated protein, p.Arg62Cys lies in DNA-binding zinc finger, whereas p.Ala154Thr lies in the hinge region of SF1 protein. Transactivation assays using reporter constructs carrying promoters of anti-Müllerian hormone (AMH), CYP11A1 and TESCO core enhancer of Sox9 showed that p.Ala154Thr and p.Arg62Cys mutations result in aberrant biological activity of NR5A1. A total of 17 patients (34%) harboured the p.Gly146Ala polymorphism.

CONCLUSION

We identified two novel NR5A1 mutations showing impaired function in 23 Egyptian XY DSD patients with hypospadias (8.5%). This is the first study searching for NR5A1 mutations in oriental patients from the Middle East and Arab region with XY DSD and no adrenal insufficiency, revealing a frequency similar to that in European patients (6.5-15%). We recommend screening of NR5A1 in patients with hypospadias and gonadal dysgenesis. Yearly follow-ups of gonadal function and early cryoconservation of sperms should be performed in XY DSD patients with NR5A1 mutations given the risk of future fertility problems due to early gonadal failure.

Mutations in DMC1 are not responsible for premature ovarian failure in Chinese women

The coding region of the disrupted meiotic cDNA gene (DMC1) was examined in 192 Chinese women with premature ovarian failure. Two known single-nucleotide polymorphisms, c.8632C>T in intron 4 and c.32377G>C in intron 10, were identified. The results suggest that mutations in the coding sequence of DMC1 are not associated with premature ovarian failure in Chinese women. The coding region of the disrupted meiotic cDNA gene (DMC1) was examined in 192 Chinese women with premature ovarian failure. Premature ovarian failure is defined as secondary amenorrhoea, infertility, oestrogen deficiency, and elevated gonadotrophin concentration in women younger than 40 years. DMC1 is a meiosis-specific gene, encoding a protein essential for meiotic homologous recombination. It participates in the formation of synaptonemal complexes and repair of double-strand breaks at recombination hotspots. Two known single-nucleotide polymorphisms, c.8632C>T in intron 4 and c.32377G>C in intron 10, were identified. No additional single-nucleotide polymorphisms or mutations were found. The results suggested mutations in the coding sequence of DMC1 are not associated with premature ovarian failure in Chinese women.

IVF for premature ovarian failure: first reported births using oocytes donated from a twin sister

BACKGROUND

Premature ovarian failure (POF) remains a clinically challenging entity because in vitro fertilisation (IVF) with donor oocytes is currently the only treatment known to be effective.

METHODS

A 33 year-old nulligravid patient with a normal karyotype was diagnosed with POF; she had a history of failed fertility treatments and had an elevated serum FSH (42 mIU/ml). Oocytes donated by her dizygotic twin sister were used for IVF. The donor had already completed a successful pregnancy herself and subsequently produced a total of 10 oocytes after a combined FSH/LH superovulation regime. These eggs were fertilised with sperm from the recipient's husband via intracytoplasmic injection and two fresh embryos were transferred to the recipient on day three.

RESULTS

A healthy twin pregnancy resulted from IVF; two boys were delivered by caesarean section at 39 weeks' gestation. Additionally, four embryos were cryopreserved for the recipient's future use. The sister-donor achieved another natural pregnancy six months after oocyte retrieval, resulting in a healthy singleton delivery.

CONCLUSION

POF is believed to affect approximately 1% of reproductive age females, and POF patients with a sister who can be an oocyte donor for IVF are rare. Most such IVF patients will conceive from treatment using oocytes from an anonymous oocyte donor. This is the first report of births following sister-donor oocyte IVF in Ireland. Indeed, while sister-donor IVF has been successfully undertaken by IVF units elsewhere, this is the only known case where oocyte donation involved twin sisters. As with all types of donor gamete therapy, pre-treatment counselling is important in the circumstance of sister oocyte donation.