The humanFOXL2 mutation database

Planned oocyte cryopreservation in women with blepharophimosis-ptosis-epicanthus inversus syndrome: a case series

Objective

To describe the experiences of three women with blepharophimosis-ptosis-epicanthus inversus syndrome (BPES) who desired to pursue planned oocyte cryopreservation.

Design

Case series.

Setting

An academic institution and a private clinic.

Patient(s)

Three nulligravid women aged 23, 25, and 34 years who desired to pursue planned oocyte cryopreservation. Two women had BPES diagnosed when they were infants and one had BPES diagnosed after presenting to discuss oocyte cryopreservation.

Intervention(s)

All three women underwent ovarian stimulation. One woman underwent three oocyte retrievals.

Main Outcomes Measure(s)

Vitrification of metaphase II oocytes.

Result(s)

One woman had a total of eight metaphase II oocytes vitrified. In addition, she underwent genetic testing that confirmed type 1 BPES. The other two women, who had BPES diagnosed when they were newborns, each underwent two cycles of ovarian stimulation. Neither of these two women responded to ovarian stimulation and both cycles were cancelled before oocyte retrieval.

Conclusion(s)

BPES is a rare condition that can lead to primary ovarian insufficiency. Early identification of this condition is important to allow for timely reproductive counseling so that oocyte cryopreservation can be offered at a young age before oocyte depletion. Careful counseling is critical for these patients, because this case series demonstrated that not all women with BPES will respond to stimulation. Further, outcomes with cryopreserved oocytes have not yet been described in women with BPES.

Premature ovarian insufficiency - the need for a genomic map

Premature ovarian insufficiency (POI) is a life-long disorder of heterogeneous etiology, presenting as adolescent primary amenorrhea in its most severe form, with an overall incidence of 1%. Idiopathic POI accounts for up to 70% of women with POI; and genomic, genetic, epidemiological, familial and cohort studies demonstrate a genetic component to this condition. Currently, the only genetic tests routinely performed in non-syndromic POI are FMR1 premutation and cytogenetics, the latter specifically for X-chromosome abnormalities. However, a myriad of genetic aberrations has been identified and implicated, some of which act in a monogenic Mendelian fashion. The presence of multiple genetic aberrations and the complexity of POI genomics are hardly surprising since the embryological formation of the primordial oocyte pool, postnatal oogenesis and folliculogenesis are all highly complex pathways. With this review, the aim is to discuss the current genetic etiologies in the emerging field of POI genomics. Promising candidate genes include STAG3, SYCE1, FIGLA, NOBOX, FSHR, BMP15 and INHA. This area has the potential to progress rapidly in light of advances in genomic technologies. The development of a POI genomic map not only will assist in understanding the underlying molecular mechanisms affecting ovarian function but will also be essential in designing predictive and diagnostic gene panels as well as future novel therapeutic strategies.

FOXL2 directs DNA double-strand break repair pathways by differentially interacting with Ku

The balance between major DNA double-strand break (DSB) repair pathways is influenced by binding of the Ku complex, a XRCC5/6 heterodimer, to DSB ends, initiating non-homologous end joining (NHEJ) but preventing additional DSB end resection and homologous recombination (HR). However, the key molecular cue for Ku recruitment to DSB sites is unknown. Here, we report that FOXL2, a forkhead family transcriptional factor, directs DSB repair pathway choice by acetylation-dependent binding to Ku. Upon DSB induction, SIRT1 translocates to the nucleus and deacetylates FOXL2 at lysine 124, leading to liberation of XRCC5 and XRCC6 from FOXL2 and formation of the Ku complex. FOXL2 ablation enhances Ku recruitment to DSB sites, imbalances DSB repair kinetics by accelerating NHEJ and inhibiting HR, and thus leads to catastrophic genomic events. Our study unveils the SIRT1-(de)acetylated FOXL2-Ku axis that governs the balance of DSB repair pathways to maintain genome integrity.

Functional study on new FOXL2 mutations found in Chinese patients with blepharophimosis, ptosis, epicanthus inversus syndrome

BACKGROUND

Blepharophimosis, ptosis, epicanthus inversus syndrome (BPES) is a rare inheritable disease that mainly affects eyelid development associated with (type I) or without (type II) ovarian dysfunction, resulting in premature ovarian failure (POF). Mutations in the gene forkhead box L2 (FOXL2) have been shown to be responsible for BPES. The aim of this study was to determine and functionally validate the FOXL2 mutation in a Chinese BPES family.

METHODS

Twelve individuals including five BPES patients from a Chinese family were enrolled. Genomic DNA was extracted from peripheral blood of enrolled subjects. The coding region of the FOXL2 gene was amplified and mutations were determined by sequencing analyses. Functional analysis was carried out to study changes in expression and transcriptional activity of the mutant FOXL2 protein.

RESULTS

A novel mutation in the FOXL2 gene (c.931C > T) was detected in all five BPES patients, which converts a histidine residue into a tyrosine (p.H311Y) in the FOXL2 protein. Functional analysis revealed that this point mutation reduces FOXL2 protein expression, concomitant with decreased transcriptional activity on the steroidogenic acute regulatory (StAR) gene promotor.

CONCLUSIONS

Our results expand the mutational spectrum of the FOXL2 gene and provide additional insights to the research on the molecular pathogenesis of FOXL2 in BPES.

Why boys will be boys and girls will be girls: Human sex development and its defects

Among the most defining events of an individual's life, is the development of a human embryo into male or a female. The phenotypic sex of an individual depends on the type of gonad that develops in the embryo, a process which itself is determined by the genetic setting of the individual. The development of the gonads is different from any other organ, as they possess the potential to differentiate into two functionally distinct organs, testes, or ovaries. Sex development can be divided into two distinctive processes, "sex determination," which is the commitment of the undifferentiated gonad into either a testis or an ovary, a process that is genetically programmed in a critically timed manner and "sex differentiation," which takes place through hormones produced by the gonads, once the developmental sex determination decision has been made. Disruption of any of the genes involved in either the testicular or ovarian development pathway could lead to disorders of sex development. In this review, we provide an insight into the factors important for sex determination, their antagonistic actions and whenever possible, references on the "prismatic" clinical cases are given. Birth Defects Research (Part C) 108:365-379, 2016. © 2016 Wiley Periodicals, Inc.

Identification of a novel FOXL2 mutation in a single family with both types of blepharophimosis‑-ptosis-epicanthus inversus syndrome

Blepharophimosis-ptosis-epicanthus inversus syndrome (BPES) is a rare autosomal dominant disease, which has been divided into two types according to whether it involves premature ovarian failure (POF). Mutations in forkhead box L2 (FOXL2) have been identified in the majority of patients with BPES. The present study aimed to identify the causative mutation in FOXL2 in a Chinese family with both types of BPES. Clinical data and genomic DNA were collected from a single Chinese family with BPES. All the coding exons and adjacent regions of FOXL2 were screened in one affected member to detect the causative mutation using Sanger sequencing. The detected mutation was also screened in available family members and in 100 normal control chromosomes. In total, seven family members were recruited in the present study, including four affected and three unaffected members. The patient (II:5) exhibited typical features of type II BPES, characterized by a narrowed horizontal palpehral aperture, ptosis, epicanthus inversus and telecanthus without POF, whereas the patient's three daughters (III:1, III:2 and III:3) were diagnosed with type I BPES, in which a complex eyelid malformation was accompanied with POF. A novel heterozygous mutation in FOXL2 (c.844_860dup17, p.His291Argfs*71) was found in the four affected members, which was absent in the remaining three unaffected members and in the 100 control chromosomes. This novel duplicate mutation (c.844_860dup17, p.His291Argfs*71) in FOXL2 was identified in a Chinese family with both types of BPES. These findings expand current knowledge of the mutation spectrum of the FOXL2 gene and confirmed the intra‑family phenotypic heterogeneity of BPES.

FOXL2 molecular status in adult granulosa cell tumors of the ovary: A study of primary and metastatic cases

Granulosa cell tumors (GCTs) of the ovary are uncommon neoplasms, accounting for ~5% of all malignant ovarian tumors. GCTs are a relatively homogeneous group of tumors, categorized into two distinct subtypes, juvenile GCT and adult GCT (AGCT), likely arising from a limited set of molecular events usually involving the disruption of pathways that regulate granulosa cell proliferation. In the present study, the presence of forkheadbox L2 (FOXL2) c.402C>G mutation was investigated in a series of 42 samples of primary and metastatic AGCT of the ovary. The samples consisted of 37 primary and 5 metastatic ovarian AGCTs from 37 patients. FOXL2 mutational status was evaluated using a pyrosequencing approach on 2.5-µm sections of formalin-fixed paraffin-embedded tissue. FOXL2 c.402C>G mutation was found in 33/37 (89.2%) primary AGCTs and in 4/5 (80.0%) metastases, with the molecular status of the metastases recapitulating that of the primary tumors (4 mutated cases and 1 wild-type case). Overall, FOXL2 mutation is present in the majority of primary and metastatic AGCTs, and could be used as a valid tool in the diagnosis of the disease and in cases of metastatic lesions from an unknown primary origin. Moreover the concordance of FOXL2 molecular status in primary and associated metastases suggests its early appearance and genomic stability in AGCT tumorigenesis.

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.

Aetiological profile of women presenting with premature ovarian failure to a single tertiary care center in Oman

BACKGROUND

Premature ovarian failure is estimated to affect at least 1%-3% of adult women. There are several aetio-pathogenic factors that may cause premature ovarian failure including iatrogenic causes, genetic, autoimmune, infectious and idiopathic. The aim of this study was to identify the aetiological profile of women with premature ovarian failure presenting to Sultan Qaboos University hospital.

METHOD

A retrospective medical record review was conducted from June 2006 to October 2012. All women diagnosed with symptoms and/or laboratory evidence of premature ovarian failure (follicle stimulating hormone ≥40 UI/L and less than 40 years of age) were enrolled in this study. Possible causes of premature ovarian failure were obtained and classified into main aetiological factors.

RESULTS

There were 90 patients during the study period, of which, 39 (43%) were following chemotherapy and bone marrow transplant. The second most common reason was idiopathic (n = 29; 31%) followed by autoimmune diseases (n = 8; 9%) and genetic disorders (n = 7; 8%). Most chemotherapy cases (69%) were among the young age group, while in the older age group idiopathic was the commonest (48%).

CONCLUSION

Compared to the world literature, the most common cause of premature ovarian failure in this study was chemotherapy induced, especially in young girls undergoing bone marrow transplantation. This is due to high prevalence of transplantable hereditary haematological disorders like thalassemia and sickle-cell disease in this part of the world. Current standard of care recommends cryopreservation of ovarian tissue to preserve ovarian function in young girls undergoing bone marrow transplantation for such disorders.

Co-occurrence of congenital hydronephrosis and FOXL2-associated blepharophimosis, ptosis, epicanthus inversus syndrome (BPES)

Blepharophimosis, ptosis, epicanthus inversus syndrome (BPES) is an autosomal dominantly inherited congenital malformation of the eyelids. Diagnostic criteria include blepharophimosis, ptosis, epicanthus inversus and telecanthus. Type І BPES has additional features of premature ovarian failure and female infertility, while type ІІ occurs isolated. We report a two-year old male child with typical features of BPES and bilateral congenital hydronephrosis. The child, first-born to non-consanguineous parents, presented to us with hypertension. Congenital hydronephrosis and reduced renal function were confirmed by renal dynamic scan. Pyeloplasty and stent placement were performed with subsequent resolution of hypertension. On follow up, growth and development are appropriate for age. His father has similar but less severe features of BPES. Sequencing of the FOXL2 gene revealed a heterozygous FOXL2 mutation c.672_701dup, which is a recurrent 30-bp duplication leading to expansion of the polyalanine tract (p.Ala225_Ala234dup), in both father and son. Additional atypical clinical features have been reported previously in BPES patients with this mutation. However, this is the first report of a renal congenital anomaly in a BPES patient with this or other mutations. Although a pleiotropic effect of the FOXL2 mutation cannot be excluded, the co-occurrence of congenital hydronephrosis and BPES may represent two different entities.

Mechanisms of activin-stimulated FSH synthesis: the story of a pig and a FOX

Activins were discovered and, in fact, named more than a quarter century ago based on their abilities to stimulate pituitary follicle-stimulating hormone (FSH) synthesis and secretion. However, it is only in the last decade that we have finally come to understand their underlying mechanisms of action in gonadotroph cells. In this minireview, we chronicle the research that led to the recent discovery of forkhead box L2 (FOXL2) as an essential mediator of activin-regulated FSH beta subunit (Fshb) transcription in vitro and in vivo.

The ovarian reserve in mammals: a functional and evolutionary perspective

The constitution and the control of the ovarian reserve is of importance in mammals and women. In particular, the number of primordial follicles at puberty is positively correlated with the number of growing follicles and their response to gonadotropin treatments. The size of this ovarian reserve depends on genes involved in germ cell proliferation and differentiation, sexual differentiation, meiosis, germ cell degeneration, formation of primordial follicles, and on a potential mechanism of self-renewal of germ stem cells. In this review, we present the state of the art of the knowledge of genes and factors involved in all these processes. We first focus on the almost 70 genes identified mainly by mouse invalidation models, then we discuss the most plausible hypothesis concerning the possibility of the existence of germ cell self-renewal by neo-oogenesis in animal species and human, with a special interest for the role of corresponding genes in evolutionary distinct model species. All of the genes pointed out here are candidates susceptible to explain fertility defects such as the premature ovarian failure in human.

FOXL2 mutation and large-scale genomic imbalances in adult granulosa cell tumors of the ovary

Adult granulosa cell tumors (AGCTs) are a rare class of ovarian tumors with recurrent cytogenetic abnormalities including trisomy 12, trisomy 14, monosomy 16/deletion 16q, and monosomy 22. Over 90% contain a missense point mutation (C134W) in the FOXL2 gene at 3q22.3. The relationship between FOXL2 mutation and cytogenetic abnormalities is unclear, although both are presumably early events in tumorigenesis. In addition, FOXL2 C134W mutant allele imbalance has been noted in a minority of AGCTs, but the mechanism for allelic imbalance has not yet been described. We used a microarray platform designed for formalin-fixed, paraffin-embedded (FFPE) tissue specimens, the Affymetrix OncoScan FFPE Express 330K Molecular Inversion Probe (MIP) array, to explore the correlation between genomic imbalances detected by microarray and FOXL2 mutation status detected by pyrosequencing in a series of 21 archived AGCTs. Tumors were characterized by histopathologic features, stage, and alpha-inhibin expression by immunohistochemistry. All tumors were positive for inhibin, and 18/21 tumors contained a FOXL2 mutation. The most common genomic imbalances were a gain of 14q, a loss of 16q, and a loss of 22q. Three tumors showed evidence of FOXL2 mutant allele imbalance by pyrosequencing; microarray revealed a 32.5 Mb deletion encompassing FOXL2 in 1 case and a 70.9 Mb stretch of homozygosity encompassing FOXL2 in the other case. The third case, with a FOXL2 mutant allele imbalance, showed a diminished mutant allele population (32%) despite high estimated tumor content (>90%), suggesting tumor heterogeneity for the mutation. This study provides the first correlation of FOXL2 mutation status and genomic imbalances in AGCTs, and it further elucidates the mechanisms for mutant allele imbalance in cancer.

Successful anesthetic management of a child with blepharophimosis syndrome and atrial septal defect for reconstructive ocular surgery

Blepharophimosis syndrome is an autosomal dominant disorder characterized by eyelid malformation, involvement of reproductive system and abnormal facial morphology leading to difficult airway. We report a rare association of blepharophimosis syndrome and atrial septal defect in a 10-year-old girl who came for reconstruction surgery of eyelid. The child had dyspnea on exertion. Atrial septal defect was identified preoperatively by clinical examination and echocardiography. Anesthesia management was complicated by failure in laryngeal mask airway placement and Cobra perilaryngeal airway was subsequently used.

Allelic reduction of Dlx5 and Dlx6 results in early follicular depletion: a new mouse model of primary ovarian insufficiency

Primary ovarian insufficiency (POI) is characterized by the loss of ovarian function before the age of 40 in humans. Although most cases of POI are idiopathic, many are familial, underlying a genetic origin of the disease. Mutations in genes involved in the control of steroidogenesis, such as NR5A1 (SF-1, Steroidogenic Factor 1), CYP17, CYP19A1 (aromatase), StAR (Steroidogenic Acute Regulatory), and the forkhead transcription factor FOXL2 have been associated with different forms of POI. In males, the homeobox transcription factors Dlx5 and Dlx6 are involved in the control of steroidogenesis through the activation of GATA4-induced-StAR transcription. Here, we analyze the potential involvement of Dlx5 and Dlx6 in female reproduction. To this end, we make use of an existing mouse model in which Dlx5 and Dlx6 are simultaneously disrupted. We show that: (i) allelic reduction of Dlx5 and Dlx6 in the mouse results in a POI-like phenotype, characterized by reduced fertility and early follicular exhaustion; (ii) in granulosa cell lines, a reciprocal regulation exists between Dlx5 and Foxl2; (iii) in the mouse ovary, allelic reduction of Dlx5/6 results in the upregulation of Foxl2. We propose that the mutual regulation between Dlx5/6 and Foxl2 and their opposite effects on StAR expression might contribute to determine the homeostatic control of steroidogenesis within the ovary. Dysregulation of this homeostatic control would result in abnormal follicular maturation and reduced fertility. Our results bring new elements to our conceptual model of follicle maturation and maintenance and provide new potential genetic targets for cases of familial POI.

Congenital and developmental eyelid abnormalities

SUMMARY

Congenital and developmental eyelid abnormalities are among the most challenging problems encountered by the reconstructive surgeon. Eyelid abnormalities in children may present at birth as a result of abnormal embryogenesis (congenital) or they may occur at later stages as the child matures (developmental). These eyelid abnormalities include entropion, ectropion, ptosis, lid retraction, epicanthal folds, blepharophimosis, colobomas, cryptophthalmos, and canthal dystopias. Additional considerations include social factors regarding the child's self-awareness of their deformities, and specific anesthetic concerns related to their pediatric problems, which are often multisystem in nature. Current methods for evaluation and medical and surgical management are reviewed for each entity.

Identification of a novel mutation in FOXL2 gene that leads to blepharophimosis ptosis epicanthus inversus and telecanthus syndrome in a Tunisian consanguineous family

Mutations in FOXL2 gene are responsible for blepharophimosis ptosis epicanthus inversus and telecanthus syndrome (BPES). The BPES syndrome is a rare autosomal dominant genetic disease characterized by eyelid malformations associated with premature ovarian failure (BPES type I) or not (BPES type II). The human FOXL2 protein (376 aa) contains a 100 amino-acid DNA-binding forkhead domain (residues 52-152) and a polyalanine tract (residues 221-234). In the present study, we report the molecular investigation of four affected members with BPES syndrome in a Tunisian consanguineous family. To identify the causative mutation, we performed a direct sequencing of the FOXL2 gene. The sequence analysis of the coding exon revealed a novel frameshift mutation g.1113 dup C, c.876 dup C, p.P292 Fs. The mutation is located downstream of the polyalanine tract and causes the protein extension to 532 aa. This study reports for the first time a novel frameshift mutation in two-generation consanguineous Tunisian family with BPES. Our results expand the spectrum of FOXL2 mutations.

Control of sex development

The process of sexual differentiation is central for reproduction of almost all metazoan, and therefore, for maintenance of practically all multicellular organisms. In sex development, we can distinguish two different processes, sex determination, that is the developmental decision that directs the undifferentiated embryo into a sexually dimorphic individual. In mammals, sex determination equals gonadal development. The second process known as sex differentiation takes place once the sex determination decision has been made through factors produced by the gonads that determine the development of the phenotypic sex. Most of the knowledge on the factors involved in sexual development came from animal models and from studies of cases in whom the genetic or the gonadal sex does not match the phenotypical sex, that is, patients affected by disorders of sex development (DSDs). Generally speaking, factors influencing sex determination are transcriptional regulators, whereas factors important for sex differentiation are secreted hormones and their receptors. This review focuses on these factors and whenever possible, references regarding the 'prismatic' clinical cases are given.

Molecular abnormalities in ovarian cancer subtypes other than high-grade serous carcinoma

Ovarian cancer is the fifth leading cause of cancer death in women in North America, and approximately two-thirds of cases of ovarian cancer are of high-grade serous type. The remaining cases are comprised of a mix of different tumor types (e.g., endometrioid, clear cell, mucinous, etc.), with no single tumor type accounting for more than 10% of ovarian cancer cases. These tumor types can be reproducibly diagnosed, and each features distinct underlying molecular events during oncogenesis, with a characteristic natural history and response rate to conventional cytotoxic chemotherapy. In this review the molecular abnormalities present in the more common non-high-grade serous subtypes of ovarian cancer will be presented. Development of targeted therapies for these tumor types will require understanding of the genetic basis of each tumor type, and may lead to subtype-specific therapy.

Mutation of FOXL2 in granulosa-cell tumors of the ovary

BACKGROUND

Granulosa-cell tumors (GCTs) are the most common type of malignant ovarian sex cord-stromal tumor (SCST). The pathogenesis of these tumors is unknown. Moreover, their histopathological diagnosis can be challenging, and there is no curative treatment beyond surgery.

METHODS

We analyzed four adult-type GCTs using whole-transcriptome paired-end RNA sequencing. We identified putative GCT-specific mutations that were present in at least three of these samples but were absent from the transcriptomes of 11 epithelial ovarian tumors, published human genomes, and databases of single-nucleotide polymorphisms. We confirmed these variants by direct sequencing of complementary DNA and genomic DNA. We then analyzed additional tumors and matched normal genomic DNA, using a combination of direct sequencing, analyses of restriction-fragment-length polymorphisms, and TaqMan assays.

RESULTS

All four index GCTs had a missense point mutation, 402C-->G (C134W), in FOXL2, a gene encoding a transcription factor known to be critical for granulosa-cell development. The FOXL2 mutation was present in 86 of 89 additional adult-type GCTs (97%), in 3 of 14 thecomas (21%), and in 1 of 10 juvenile-type GCTs (10%). The mutation was absent in 49 SCSTs of other types and in 329 unrelated ovarian or breast tumors.

CONCLUSIONS

Whole-transcriptome sequencing of four GCTs identified a single, recurrent somatic mutation (402C-->G) in FOXL2 that was present in almost all morphologically identified adult-type GCTs. Mutant FOXL2 is a potential driver in the pathogenesis of adult-type GCTs.

FOXL2 mutations and genomic rearrangements in BPES

The FOXL2 gene is one of 10 forkhead genes, the mutations of which lead to human developmental disorders, often with ocular manifestations. Mutations in FOXL2 are known to cause blepharophimosis syndrome (BPES), an autosomal dominant eyelid malformation associated (type I) or not (type II) with ovarian dysfunction, leading to premature ovarian failure (POF). In addition, a few mutations have been described in patients with isolated POF. Here, we review all currently described FOXL2 sequence variations and genomic rearrangements in BPES and POF. Using a combined mutation detection approach, it is possible to identify the underlying genetic defect in a major proportion (88%) of typical BPES patients. Of all genetic defects found in our BPES cohort, intragenic mutations represent 81%. They include missense changes, frameshift and nonsense mutations, in-frame deletions, and duplications, that are distributed along the single-exon gene. Genomic rearrangements comprising both deletions encompassing FOXL2 and deletions located outside its transcription unit, represent 12% and 5% of all genetic defects in our BPES cohort, respectively. One of the challenges of genetic testing in BPES is the establishment of genotype-phenotype correlations, mainly with respect to the ovarian phenotype. Genetic testing should be performed in the context of genetic counseling, however, and should be systematically complemented by a multidisciplinary clinical follow-up. Another challenge for health care professionals involved in BPES is the treatment of the eyelid phenotype and the prevention or treatment of POF.

FOXL2: at the crossroads of female sex determination and ovarian function

The gene FOXL2 encodes a forkhead transcription factor whose mutations are responsible for the blepharophimosis ptosis epicanthus-inversus syndrome. This genetic disorder is characterized by eyelid and mild craniofacial abnormalities often in association with premature ovarian failure. FOXL2 orthologs are found throughout the animal phylum and its sequence is highly conserved in vertebrates. FOXL2 is one of the earliest ovarian markers and it offers, alongwith its targets, a model to study ovarian development and function. In this chapter, we review recent data concemingits mutations, targets, regulation and functions. Studies of the cellular consequences of FOXL2 mutations seem to indicate that aggregation is a common pathogenic mechanism. However, no reliable genotype/phenotype correlation has been established to predict the exact impact of point mutations in the coding region of FOXL2. FOXL2 has been suggested to be involved in the regulation of cholesterol homeostasis, steroid metabolism, apoptosis, reactive oxygen species detoxification and inflammation processes. Interestingly, all these processes are not equally affected by FOXL2 mutations. The elucidation of the impact of the FOXL2 function in the ovary will allow a better understanding of normal ovarian development and function as well as the pathogenic mechanisms underlying BPES.

Blepharophimosis-ptosis-epicanthus inversus syndrome in a girl with chromosome translocation t(2;3)(q33;q23)

We report on a young female patient with the clinical features of blepharophimosis-ptosis-epicanthus inversus syndrome (BPES, OMIM 110100) and a balanced chromosome translocation 46, XX, t(2;3)(q33;q23)dn.BPES is a rare autosomal dominant congenital disorder characterized by the eponymous oculo-facial features that are, in female patients, associated either with (type 1 BPES) or without (type 2 BPES) premature ovarian failure. Both types of BPES are caused by heterozygous mutations in the FOXL2 gene, which is located in chromosome band 3q23. Chromosome aberrations such as balanced rearrangements have only rarely been observed in BPES patients but can provide valuable information about regulatory regions of FOXL2. The translocation in this patient broadens our knowledge of pathogenic mechanisms in BPES and highlights the importance of conventional cytogenetic investigations in patients with negative results of FOXL2 mutation screening as a prerequisite for optimal management and genetic counseling.

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.

Foxl2 function in ovarian development

Foxl2 is a forkhead transcription factor essential for proper reproductive function in females. Human patients carrying mutations in the FOXL2 gene display blepharophimosis/ptosis/epicanthus inversus syndrome (BPES), an autosomal dominant disease associated with eyelid defects and premature ovarian failure in females. Recently, animal models for BPES have been developed that in combination with a catalogue of human FOXL2 mutations provide further insight into its molecular function. Mice homozygous mutant for Foxl2 display craniofacial malformations and female infertility. The analysis of the murine phenotype has revealed that Foxl2 is required for granulosa cell function. These ovarian somatic cells surround and nourish the oocyte and play an important role in follicle formation and activation. Mutations upstream of FOXL2 in humans, not affecting the coding sequence itself, have also been shown to cause BPES, which points to the existence of a distant regulatory element necessary for proper gene expression. The same regulatory sequences may be deleted in the goat polled intersex syndrome (PIS), in which FoxL2 expression is severely reduced. Sequence comparison of FoxL2 from several vertebrate species has shown that it is a highly conserved gene involved in ovary development. Thus, the detailed understanding of Foxl2 function and regulation and the identification of its transcriptional targets may open new avenues for the treatment of female infertility in the future.

An investigation into FOXE1 polyalanine tract length in premature ovarian failure

Premature ovarian failure (POF) is a common condition affecting 1% of women worldwide. There is strong evidence for genetic involvement in POF as many cases are familial, and mutations in several genes have been associated with POF. We investigated variation in FOXE1 polyalanine tract length, following the observation that polyalanine tract deletions are seen in the closely related FOXL2 in patients with POF. In addition, polyalanine tract expansions in FOXL2 are often seen in patients with blepharophimosis-ptosis-epicanthus inversus syndrome (BPES), a rare eyelid disorder often associated with POF. The FOXE1 polyalanine tract shows marked variation in its length between POF patients and normal controls, existing as an allele of 12, 14, 16, 17 or 19 alanine residues. We found evidence to suggest that variation in FOXE1 polyalanine tract length predisposes to POF.

Mutation analysis of the FOXL2 gene in Chinese patients with blepharophimosis–ptosis–epicanthus inversus syndrome

Blepharophimosis-ptosis-epicanthus inversus syndrome (BPES) is an autosomal dominant disorder characterized by blepharophimosis, ptosis and epicanthus inversus. Based on the presence and absence of premature ovarian failure, two clinical types have been distinguished. Both types of BPES have been mapped to chromosome 3q23 and are mostly due to mutations of a forkhead transcription factor FOXL2 gene which locates at this region. We screened for FOXL2 mutations in Chinese patients with BPES. A novel mutation (g.901-930dup30) which could result in an expansion of the polyalanine tract was found in two BPES type II families and one sporadic case. In addition, a new g.952delC mutation was identified in two patients from a BPES family of undetermined type. The previously reported g.892C>T (p.Q219X) was also found in 12 patients from a large BPES family of type I. No mutations were detected in three other BPES families and three sporadic cases. So we speculate that in a fraction of the BPES patients the genetic defect may represent a change in gene dosage or a rearrangement outside the transcription unit of FOXL2.

Premature ovarian failure

Premature ovarian failure (POF) causing hypergonadotrophic hypogonadism occurs in 1% of women. In majority of cases the underlying cause is not identified. The known causes include: (a) Genetic aberrations, which could involve the X chromosome or autosomes. A large number of genes have been screened as candidates for causing POF; however, few clear causal mutations have been identified. (b) Autoimmune ovarian damage, as suggested by the observed association of POF with other autoimmune disorders. Anti-ovarian antibodies are reported in POF by several studies, but their specificity and pathogenic role are questionable. (c) Iatrogenic following surgical, radiotherapeutic or chemotherapeutic interventions as in malignancies. (d) Environmental factors like viral infections and toxins for whom no clear mechanism is known. The diagnosis is based on finding of amenorrhoea before age 40 associated with FSH levels in the menopausal range. Screening for associated autoimmune disorders and karyotyping, particularly in early onset disease, constitute part of the diagnostic work-up. There is no role of ovarian biopsy or ultrasound in making the diagnosis. Management essentially involves hormone replacement and infertility treatment, the only proven means for the latter being assisted conception with donated oocytes. Embryo cryopreservation, ovarian tissue cryopreservation and oocyte cryopreservation hold promise in cases where ovarian failure is foreseeable as in women undergoing cancer treatments.