The genetics of disorders of sex development in humans

46,XX Differences of Sex Development outside congenital adrenal hyperplasia: pathogenesis, clinical aspects, puberty, sex hormone replacement therapy and fertility outcomes

The term 'differences of sex development' (DSD) refers to a group of congenital conditions that are associated with atypical development of chromosomal, gonadal, and/or anatomical sex. DSD in individuals with a 46,XX karyotype can occur due to fetal or postnatal exposure to elevated amount of androgens or maldevelopment of internal genitalia. Clinical phenotype could be quite variable and for this reason these conditions could be diagnosed at birth, in newborns with atypical genitalia, but also even later in life, due to progressive virilization during adolescence, or pubertal delay. Understand the physiological development and the molecular bases of gonadal and adrenal structures is crucial to determine the diagnosis and best management and treatment for these patients. The most common cause of DSD in 46,XX newborns is congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency, determining primary adrenal insufficiency and androgen excess. In this review we will focus on the other rare causes of 46,XX DSD, outside CAH, summarizing the most relevant data on genetic, clinical aspects, puberty and fertility outcomes of these rare diseases.

Mutations in STARD8 (DLC3) May Cause 46,XY Gonadal Dysgenesis

INTRODUCTION

46,XY gonadal dysgenesis is a condition that is characterised by undeveloped testes in individuals with a male karyotype. Mutations in many genes that underlie this condition have been identified; however, there are still a considerable number of patients with an unknown genetic background. Recently, a mutation in the STARD8 X-linked gene in two sisters with 46,XY gonadal dysgenesis has been reported. It was localised within the START domain, whose homologue in Drosophila is responsible for maintaining testes integrity during their development.

METHODS

We analysed the potential pathogenicity of another STARD8 mutation, p.R887C, that was identified in a patient with 46,XY asymmetric gonadal dysgenesis. For this purpose, molecular dynamics simulations were performed.

RESULTS

These simulations revealed the full rearrangement of the helix containing the p.R887C substitution upstream from the START domain, which may cause STARD8 protein dysfunction and contribute to 46,XY gonadal dysgenesis. A comparison of the phenotypes of the three described 46,XY gonadal dysgenesis patients that harbour STARD8 mutations indicated that alterations of this gene can result in a partial or complete gonadal dysgenesis phenotype.

CONCLUSION

Based on these and previous results, it is reasonable to include STARD8 in gene panels for 46,XY gonadal dysgenesis.

The use of in silico extreme pathway (ExPa) analysis to identify conserved reproductive transcriptional-regulatory networks in humans, mice, and zebrafish

Vertebrate sex determination and differentiation are coordinated by the activations and maintenance of reproductive transcriptional-regulatory networks (TRNs). There is considerable interest in studying the conserved design principles and functions of reproductive TRNs given that their intricate regulation is susceptible to disruption by gene mutations or exposures to exogenous endocrine disrupting chemicals (or EDCs). In this manuscript, the Boolean rules describing reproductive TRNs in humans, mice, and zebrafish, were represented as a pseudo-stoichiometric matrix model. This model mathematically described the interactions of 35 transcription factors with 21 sex determination and differentiation genes across the three species. The in silico approach of Extreme Pathway (ExPa) analysis was used to predict the extent of TRN gene activations subject to the species-specific transcriptomics data, from across various developmental life-stages. A goal of this work was to identify conserved and functional reproductive TRNs across the three species. ExPa analyses predicted the sex differentiation genes, DHH, DMRT1, and AR, to be highly active in male humans, mice, and zebrafish. Whereas FOXL2 was the most active gene in female humans and mice; and CYP19A1A in female zebrafish. These results agree with the expectation that regardless of a lack of sex determination genes in zebrafish, the TRNs responsible for canalizing male vs. female sexual differentiation are conserved with mammalian taxa. ExPa analysis therefore provides a framework with which to study the TRNs that influence the development of sexual phenotypes. And the in silico predicted conservation of sex differentiation TRNs between mammals and zebrafish identifies the piscine species as an effective in vivo model to study mammalian reproductive systems under normal or perturbed pathologies.

Genetic control of typical and atypical sex development

Sex development relies on the sex-specific action of gene networks to differentiate the bipotential gonads of the growing fetus into testis or ovaries, followed by the differentiation of internal and external genitalia depending on the presence or absence of hormones. Differences in sex development (DSD) arise from congenital alterations during any of these processes, and are classified depending on sex chromosomal constitution as sex chromosome DSD, 46,XY DSD or 46,XX DSD. Understanding the genetics and embryology of typical and atypical sex development is essential for diagnosing, treating and managing DSD. Advances have been made in understanding the genetic causes of DSD over the past 10 years, especially for 46,XY DSD. Additional information is required to better understand ovarian and female development and to identify further genetic causes of 46,XX DSD, besides congenital adrenal hyperplasia. Ongoing research is focused on the discovery of further genes related to typical and atypical sex development and, therefore, on improving diagnosis of DSD.

A data-driven optimization method for coarse-graining gene regulatory networks

One major challenge in systems biology is to understand how various genes in a gene regulatory network (GRN) collectively perform their functions and control network dynamics. This task becomes extremely hard to tackle in the case of large networks with hundreds of genes and edges, many of which have redundant regulatory roles and functions. The existing methods for model reduction usually require the detailed mathematical description of dynamical systems and their corresponding kinetic parameters, which are often not available. Here, we present a data-driven method for coarse-graining large GRNs, named SacoGraci, using ensemble-based mathematical modeling, dimensionality reduction, and gene circuit optimization by Markov Chain Monte Carlo methods. SacoGraci requires network topology as the only input and is robust against errors in GRNs. We benchmark and demonstrate its usage with synthetic, literature-based, and bioinformatics-derived GRNs. We hope SacoGraci will enhance our ability to model the gene regulation of complex biological systems.

Whole exome sequencing reveals copy number variants in individuals with disorders of sex development

Complete androgen insensitivity syndrome (CAIS), where 46,XY individuals present as female, is caused by variants in the androgen receptor gene (AR). We analyzed the DNA of a patient with suspected CAIS using a targeted gene sequencing panel and whole exome sequencing (WES) but did not detect any small nucleotide variants in AR. Analysis of WES data using our bioinformatics pipeline designed to detect copy number variations (CNV) uncovered a rare duplication of exon 2 of AR. Using array comparative genomic hybridization, the duplication was found to span 43.6 kb and is predicted to cause a frameshift and loss of AR protein. We confirmed the power of our WES-CNV detection protocol by identifying pathogenic CNVs in FSHR and NR5A1 in previously undiagnosed patients with disorders of sex development. Our findings illustrate the usefulness of CNV analysis in WES data to detect pathogenic genomic changes that may go undetected using only standard analysis protocols.

Genetics of human sexual development and related disorders

PURPOSE OF REVIEW

The aim of this study was to provide a basic overview on human sex development with a focus on involved genes and pathways, and also to discuss recent advances in the molecular diagnostic approaches applied to clinical workup of individuals with a difference/disorder of sex development (DSD).

RECENT FINDINGS

Rapid developments in genetic technologies and bioinformatics analyses have helped to identify novel genes and genomic pathways associated with sex development, and have improved diagnostic algorithms to integrate clinical, hormonal and genetic data. Recently, massive parallel sequencing approaches revealed that the phenotype of some DSDs might be only explained by oligogenic inheritance.

SUMMARY

Typical sex development relies on very complex biological events, which involve specific interactions of a large number of genes and pathways in a defined spatiotemporal sequence. Any perturbation in these genetic and hormonal processes may result in atypical sex development leading to a wide range of DSDs in humans. Despite the huge progress in the understanding of molecular mechanisms underlying DSDs in recent years, in less than 50% of DSD individuals, the genetic cause is currently solved at the molecular level.

Behavioral Health Diagnoses in Youth with Differences of Sex Development or Congenital Adrenal Hyperplasia Compared with Controls: A PEDSnet Study

OBJECTIVE

To evaluate the odds of a behavioral health diagnosis among youth with differences of sex development (DSD) or congenital adrenal hyperplasia (CAH) compared with matched controls in the PEDSnet database.

STUDY DESIGN

All youth with a diagnosis of DSD (n = 1216) or CAH (n = 1647) and at least 1 outpatient encounter were extracted from the PEDSnet database and propensity-score matched on 8 variables (1:4) with controls (n = 4864 and 6588, respectively) using multivariable logistic regression. The likelihood of having behavioral health diagnoses was examined using generalized estimating equations.

RESULTS

Youth with DSD had higher odds of a behavioral health diagnosis (OR, 1.7; 95% CI, 1.4-2.1; P < .0001) and neurodevelopmental diagnosis (OR, 1.7; 95% CI, 1.4, 2.0; P < .0001) compared with matched controls. Youth with CAH did not have an increased odds of a behavioral health diagnosis (OR, 1.0; 95% CI, 0.9, 1.1; P = .9) compared with matched controls but did have higher odds of developmental delay (OR, 1.8; 95% CI, 1.4, 2.4; P < .0001).

CONCLUSIONS

Youth with DSD diagnosis have higher odds of a behavioral health or neurodevelopmental diagnosis compared with matched controls. Youth with CAH have higher odds of developmental delay, highlighting the need for screening in both groups.

Establishing a molecular genetic diagnosis in children with Differences of Sex Development - a clinical approach

Background Despite distinct underlying aetiologies, the clinical phenotypes and hormonal profiles of children with various differences of sex development (DSD) are often similar, which presents challenges to ascertaining an accurate diagnosis on clinical grounds alone. Associated features and important clinical outcomes can, however, vary significantly in different DSD, thus establishing an accurate molecular diagnosis may have important implications for decision-making and management planning in a given individual. Summary The wider availability of next generation sequencing techniques in recent years has led to recommendations for earlier integration of genetic testing in the diagnostic pathway of children with DSD. This review provides a practical overview of the clinical applications, advantages and limitations of the more commonly available diagnostic genetic tests and outlines a suggested approach to testing. The potential clinical implications of a confirmed genetic diagnosis on subsequent management pathways for individuals with DSD, as well as challenges that remain to be addressed are also outlined. Key messages Despite significant improvements in our understanding of the complex genetic pathways that underlie DSD, an accurate diagnosis still eludes many affected individuals. Establishing a molecular diagnosis provides aetiological certainty, enabling improved information for families and individualised clinical management, including monitoring or prophylactic intervention where higher longer-term health risks exist. A stepwise approach to genomic testing is recommended to afford highest diagnostic yield from available resources. Looking forward, collaborative multicentre prospective studies will be required to assess the true impact of a genetic diagnosis on improving clinical care pathways and health, wellbeing and patient-reported outcomes for individuals with DSD.

Targeting the Non-Coding Genome for the Diagnosis of Disorders of Sex Development

Disorders of sex development (DSD) are a complex group of conditions with highly variable clinical phenotypes, most often caused by failure of gonadal development. DSD are estimated to occur in around 1.7% of all live births. Whilst the understanding of genes involved in gonad development has increased exponentially, approximately 50% of patients with a DSD remain without a genetic diagnosis, possibly implicating non-coding genomic regions instead. Here, we review how variants in the non-coding genome of DSD patients can be identified using techniques such as array comparative genomic hybridization (CGH) to detect copy number variants (CNVs), and more recently, whole genome sequencing (WGS). Once a CNV in a patient's non-coding genome is identified, putative regulatory elements such as enhancers need to be determined within these vast genomic regions. We will review the available online tools and databases that can be used to refine regions with potential enhancer activity based on chromosomal accessibility, histone modifications, transcription factor binding site analysis, chromatin conformation, and disease association. We will also review the current in vitro and in vivo techniques available to demonstrate the functionality of the identified enhancers. The review concludes with a clinical update on the enhancers linked to DSD.

Towards improved genetic diagnosis of human differences of sex development

Despite being collectively among the most frequent congenital developmental conditions worldwide, differences of sex development (DSD) lack recognition and research funding. As a result, what constitutes optimal management remains uncertain. Identification of the individual conditions under the DSD umbrella is challenging and molecular genetic diagnosis is frequently not achieved, which has psychosocial and health-related repercussions for patients and their families. New genomic approaches have the potential to resolve this impasse through better detection of protein-coding variants and ascertainment of under-recognized aetiology, such as mosaic, structural, non-coding or epigenetic variants. Ultimately, it is hoped that better outcomes data, improved understanding of the molecular causes and greater public awareness will bring an end to the stigma often associated with DSD.

Morphology of the genital organs of male and female giant anteaters (Myrmecophaga tridactyla)

BACKGROUND

The giant anteater belongs to the supraorder Xenarthra which occupies a systematically isolated position among placental mammals. The species is categorized as Vulnerable by the International Union for Conservation of Nature, and understanding its reproductive characteristics is critical for future conservation efforts.

METHODS

Gross and microscopic anatomy of the genital organs of 23 male and 21 female adult and young roadkill giant anteaters in Brazil were studied.

RESULTS

Male giant anteaters presented a short conical penis, intraabdominal testes, and prostate, vesicular and bulbourethral glands. A tubular remnant of the partially fused Müllerian ducts extended from the seminal colliculus through the prostate gland, continued cranially in the genital fold, bifurcated, and attached with one elongation each to the left and right epididymal corpus. The structure presented a total length of up to 10 cm and contained a yellowish liquid in its lumen. Histologically, the caudal section of this structure resembled the female vagina, the middle portion corresponded to the uterus, and the extensions showed characteristics of uterine tubes. In adult female giant anteaters, ovoid ovaries with occasional seminiferous cord-like structures were observed. The animals possessed a simple uterus, which was directly continuous with the vaginal canal. The caudal portion of the vagina had two lumina, separated by a longitudinal septum and opening into two apertures into the vaginal vestibule, cranial to the urethral opening. In the urethral and the lateral vestibular wall, glandular structures with characteristics of male prostate and bulbourethral glands, respectively, were found. The vestibule opened through a vertical vulvar cleft to the exterior. A pair of well-differentiated Wolffian ducts with a central lumen originated ventrally at the vaginal opening into the vestibule and passed in a cranial direction through the ventral vaginal and uterine wall. Each duct extended highly coiled along the ipsilateral uterine tube until the lateral pole of the ovaries where it merged with the rete ovarii.

DISCUSSION

The reproductive morphology of giant anteaters reveals characteristics shared with other Xenarthrans: intraabdominal testes, a simple uterus, and a double caudal vagina. The persistence of well-differentiated genital ducts of the opposite sex in both males and females, however, singles them out among other species. These structures are the results of an aberration during fetal sexual differentiation and possess secretory functions. The possibility of a pathological degeneration of these organs should be considered in reproductive medicine of the species.

CONCLUSION

Knowledge of the unique reproductive characteristics of the giant anteater is essential for future reproductive management of the species. Additionally, further research on the peculiarities of the persisting genital duct structures might help to understand sexual differentiation in placental mammals in general.

A missense mutation (c.226C>A) in HMG box SRY gene affects nNLS function in 46,XY sex reversal female

The SRY initiates cascade of gene expression that transforms the undifferentiated gonad, genital ridge into testis. Mutations of the SRY gene is associated with complete gonadal dysgenesis in females with 46,XY karyotype. Primary amenorrhea is one of the clinical findings to express the genetic cause in 46,XY sex reversal. Here, we report a 26-year-old married woman presenting with primary amenorhea and complete gonadal dysgenesis. The clinical phenotypes were hypoplastic uterus with streak gonad and underdeveloped secondary sexual characters. The cytogenetic analysis confirmed 46,XY sex reversal karyotype of a female. Using molecular approach, we screened open reading frame of the SRY gene by PCR and targeted DNA Sanger sequencing. The patient was confirmed with nucleotide substitution (c.226C>A; p.Arg76Ser) at in HMG box domain of SRY gene that causes 46,XY sex reversal female. Mutation prediction algorithms suggest that alteration might be disease causing mutation and mutated (p.Arg76Ser) amino acid deleteriously affects HMG box nNLS region of SRY protein. Clinical phenotypes and in silico analysis confirmed that missense substitution (p.Arg76Ser) impaired nNLS binding Calmodulin-mediated nuclear transport of SRY from cytoplasm to nucleus. The mutation affects down regulation of male sex differentiation pathway and is responsible for 46,XY sex reversal female with gonadal dysgenesis.

Reproductive health research in Australia and New Zealand: highlights from the Annual Meeting of the Society for Reproductive Biology, 2019

The 2019 meeting of the Society for Reproductive Biology (SRB) provided a platform for the dissemination of new knowledge and innovations to improve reproductive health in humans, enhance animal breeding efficiency and understand the effect of the environment on reproductive processes. The effects of environment and lifestyle on fertility and animal behaviour are emerging as the most important modern issues facing reproductive health. Here, we summarise key highlights from recent work on endocrine-disrupting chemicals and diet- and lifestyle-induced metabolic changes and how these factors affect reproduction. This is particularly important to discuss in the context of potential effects on the reproductive potential that may be imparted to future generations of humans and animals. In addition to key summaries of new work in the male and female reproductive tract and on the health of the placenta, for the first time the SRB meeting included a workshop on endometriosis. This was an important opportunity for researchers, healthcare professionals and patient advocates to unite and provide critical updates on efforts to reduce the effect of this chronic disease and to improve the welfare of the women it affects. These new findings and directions are captured in this review.

Late-onset vanishing testis-like syndrome in a 38,XX/38,XY agonadic pig (Sus scrofa)

Here we describe the case of a pig with intersex traits including ambiguous external genitalia, sex chromosome abnormalities and a late-onset vanishing testis-like syndrome. It was identified shortly after birth by presenting a predominantly female phenotype with two large scrotal masses resembling testes. The karyotype is 38,XX (53%)/38,XY (47%). Sex steroid levels were undetectable at 1 and 7 months old, whereas circulating cortisol levels were typical. DNA studies excluded gene alterations in sex-determining region Y (SRY), dosage-sensitive sex reversal-congenital adrenal hypoplasia critical region on the X chromosome protein 1 (DAX1), SRY-related high mobility group-box gene 9 (SOX9), nuclear receptor subfamily 5, group a, member 1 (NR5A1), nuclear receptor subfamily 3, group c, member 4 (NR3C4) and steroid 5-alpha-reductase 2 (SRD5A2). At 8 months of age the XX/XY pig evinced delayed growth; however, the most striking phenotypic change was that the testes-like structures completely vanished in a 2-3-week period. The internal genitalia were found to consist of a portion of a vagina and urethra. No fallopian tubes, uterus or remnants of Wolffian derivatives were observed. More importantly, no testes, ovaries, ovotestis or gonadal streaks could be identified. The XX/XY sex chromosome dosage and/or overexpression of the DAX1 gene on the X chromosome in the presence of a wild-type SRY gene may have caused this predominantly female phenotype. This specimen represents an atypical case of 38,XX/38,XY chimeric, ovotesticular disorder of sex development associated with agonadism.

Disorders of sexual development with XY karyotype and female phenotype: clinical findings and genetic background in a cohort from a single centre

PURPOSE

46, XY disorders (or differences) of sex development (DSD) are a group of clinical conditions with variable genetic background; correct diagnosis is often difficult, but it permits to optimize the management. The aim of this study is to identify clinical and genetics features of a group of women with 46, XY DSD to define some issues characterizing people with 46, XY DSD in Italy.

METHODS

Retrospective analysis of girls and women with 46, XY DSD and female phenotype evaluated between year 2000 and 2016, performed by anonymised database, focusing on the clinical features and management, including presentation, first diagnostic suspect, gonadal surgery and molecular diagnostic delay.

RESULTS

A total of 84 records were collected (mean age at clinical presentation: 9.1 ± 7.9 years; mean age at definitive diagnosis: 20.1 ± 15.0 years). Complete androgen insensitivity syndrome was the most common diagnosis (60%). Only 12 patients (14.3%) did not receive a molecular diagnosis. Early misdiagnoses frequently occurred; diagnostic delay was 10.2 ± 11.2 years, being reduced in patients presenting from 2007 to 2016. The discordance between genotypic and phenotypic sex during pregnancy or at birth determined early reason for referral in a considerable percentage (4.9%).

CONCLUSION

Misdiagnosis and long diagnostic delays are present in females with 46, XY DSD in Italy, but the new genetic techniques permit faster right diagnoses in the last years. The centralization in dedicated third level units permits to reduce the number of patients without a molecular diagnosis, allowing better clinical management and appropriate genetic counselling.

Disorders/Differences of Sex Development Presenting in the Newborn With 46,XY Karyotype

Differences/disorders of sex development (DSD) are a heterogeneous group of congenital conditions, resulting in discordance between an individual's sex chromosomes, gonads, and/or anatomic sex. The management of a newborn with suspected 46,XY DSD remains challenging. Newborns with 46,XY DSD may present with several phenotypes ranging from babies with atypical genitalia or girls with inguinal herniae to boys with micropenis and cryptorchidism. A mismatch between prenatal karyotype and female phenotype is an increasing reason for presentation. Gender assignment should be avoided prior to expert evaluation and possibly until molecular diagnosis. The classic diagnostic approach is time and cost-consuming. Today, a different approach may be considered. The first line of investigations must exclude rare life-threatening diseases related to salt wasting crises. Then, the new genetic tests should be performed, yielding increased diagnostic performance. Focused imaging or endocrine studies should be performed on the basis of genetic results in order to reduce repeated and invasive investigations for a small baby. The challenge for health professionals will lie in integrating specific genetic information with better defined clinical and endocrine phenotypes and in terms of long-term evolution. Such advances will permit optimization of counseling of parents and sex assignment. In this regard, society has significantly changed its attitude to the acceptance and expansion beyond strict binary male and female sexes, at least in some countries or cultures. These management advances should result in better personalized care and better long-term quality of life of babies born with 46,XY DSD.

Identification and functional analysis of fourteen NR5A1 variants in patients with the 46 XY disorders of sex development

Human sex determination and differentiation is a complex process, during which NR5A1 plays a central role via the transcriptional regulation of key modulators involved in steroidogenesis. Approximately 8-15% of 46,XY DSD are caused by variants in the NR5A1 gene. Therefore, screening for variants in the NR5A1 gene was performed in a Chinese cohort of sixty-two 46,XY DSD patients with no AR or SRD5A2 variants via next-generation sequencing (NGS). Fourteen variants in the NR5A1 gene were identified in 16 patients from 14 unrelated families, including nine novel variants. These variants included eight heterozygote missense variants, two heterozygote frameshift variants, two heterozygote nonsense variants, one heterozygote nonframeshift deletion-insertion variant, and one homozygous missense variant. Functional assays showed that the transcriptional activity of the 11 variants was significantly reduced. In this study, 11 NR5A1 pathogenic variants were identified. These novel variants further expand the existing spectrum of the NR5A1 variants associated with 46,XY DSD, which will, in turn, assist in the molecular diagnosis of DSD.

Sex determination, gonadal sex differentiation, and plasticity in vertebrate species

A diverse array of sex determination (SD) mechanisms, encompassing environmental to genetic, have been found to exist among vertebrates, covering a spectrum from fixed SD mechanisms (mammals) to functional sex change in fishes (sequential hermaphroditic fishes). A major landmark in vertebrate SD was the discovery of the SRY gene in 1990. Since that time, many attempts to clone an SRY ortholog from nonmammalian vertebrates remained unsuccessful, until 2002, when DMY/dmrt1by was discovered as the SD gene of a small fish, medaka. Surprisingly, however, DMY/dmrt1by was found in only 2 species among more than 20 species of medaka, suggesting a large diversity of SD genes among vertebrates. Considerable progress has been made over the last 3 decades, such that it is now possible to formulate reasonable paradigms of how SD and gonadal sex differentiation may work in some model vertebrate species. This review outlines our current understanding of vertebrate SD and gonadal sex differentiation, with a focus on the molecular and cellular mechanisms involved. An impressive number of genes and factors have been discovered that play important roles in testicular and ovarian differentiation. An antagonism between the male and female pathway genes exists in gonads during both sex differentiation and, surprisingly, even as adults, suggesting that, in addition to sex-changing fishes, gonochoristic vertebrates including mice maintain some degree of gonadal sexual plasticity into adulthood. Importantly, a review of various SD mechanisms among vertebrates suggests that this is the ideal biological event that can make us understand the evolutionary conundrums underlying speciation and species diversity.

Applying Single-Cell Analysis to Gonadogenesis and DSDs (Disorders/Differences of Sex Development)

The gonads are unique among the body's organs in having a developmental choice: testis or ovary formation. Gonadal sex differentiation involves common progenitor cells that form either Sertoli and Leydig cells in the testis or granulosa and thecal cells in the ovary. Single-cell analysis is now shedding new light on how these cell lineages are specified and how they interact with the germline. Such studies are also providing new information on gonadal maturation, ageing and the somatic-germ cell niche. Furthermore, they have the potential to improve our understanding and diagnosis of Disorders/Differences of Sex Development (DSDs). DSDs occur when chromosomal, gonadal or anatomical sex are atypical. Despite major advances in recent years, most cases of DSD still cannot be explained at the molecular level. This presents a major pediatric concern. The emergence of single-cell genomics and transcriptomics now presents a novel avenue for DSD analysis, for both diagnosis and for understanding the molecular genetic etiology. Such -omics datasets have the potential to enhance our understanding of the cellular origins and pathogenesis of DSDs, as well as infertility and gonadal diseases such as cancer.

Gender Dysphoria: A Review Investigating the Relationship Between Genetic Influences and Brain Development

Gender dysphoria (GD) is a facet of modern human biology which is believed to be derived from the sexual differentiation of the brain. GD “involves a conflict between a person’s physical or assigned gender and the gender with which he/she/they identify”, as defined in the DSM-5. Individuals report feeling uncomfortable and faced with prejudice from those around them, affecting their mental health. Elucidating the relationship between genetic influences on gonadal and brain development could give an insight into understanding this clinical condition. To explore this issue, a review of the literature database was carried out. Evidence suggests that abnormal biological processes, including mutations in certain genes, can lead to abnormal gonadal development, causing some fetuses to present with indifferent gonads and to be reassigned at birth to the default female sex. This disparity in genetic influences relates to an increased likelihood of a diagnosis of GD. An investigation into complete androgen insensitivity syndrome, involving androgen receptor (AR) gene mutation, suggests that such individuals also experience GD. It is known that the brains of males and females are different. Evidence further suggests that brain anatomy and neuronal signaling pathways are more closely aligned with a person’s perceived gender identity. Individuals who present with discordant gonadal and brain developments experience psychological challenges that may contribute to a state of unease or generalized dissatisfaction with their biological sex. These point to a possible biological and genetic underpinning of GD as stemming from a discordance between gonadal and brain development. However, not enough evidence has associated these differences with GD. Further research is required to elucidate the true mechanisms and possible inheritance pattern of GD for a better education and greater understanding by clinicians and the general public on perceptions regarding GD.

True hermaphroditism with dysgerminoma: A case report

INTRODUCTION

True hermaphroditism is a rare and usually sporadic disorder. It is defined by the presence of both ovarian and testicular tissues together as ovotestis.

PATIENT CONCERNS

In this study, we reported a rare true hermaphroditism case with dysgerminoma. A 49-year-old woman developed masses in both inguinal regions for 30 years. Recently 3 months, the patient found that the size of mass in her left inguinal region was significantly increased.

DIAGNOSIS

After surgical resection, the results of immunohistochemical examination in left mass revealed a dysgerminoma with positive expression of placental alkaline phosphatase and octamer-binding transcription factor 3/4, and right mass was a cryptorchidism. Chromosomal analysis revealed the karyotype 46, XY. Combined immunohistochemical and karyotype analysis, a diagnosis of true hermaphroditism with dysgerminoma was made.

INTERVENTIONS

Radiotherapy combined with chemotherapy after tumor resection was used to improve her prognosis. Hormone replacement therapy with conjugated estrogen and medroxyprogesterone acetate were used to maintain her female characteristics.

OUTCOMES

The patient underwent hormonal replacement and has been well for 6 months.

CONCLUSION

The positive expression of placental alkaline phosphatase and octamer-binding transcription factor 3/4 could be 2 diagnosis markers of dysgerminoma. Surgery combined with radiotherapy and chemotherapy could improve the prognosis of dysgerminoma. Moreover, hormone replacement therapy with conjugated estrogen and medroxyprogesterone acetate was very helpful to maintain the female characteristic of patients with true hermaphroditism.

A missense mutation in NR5A1 causing female to male sex reversal: A case report

Testicular disorder of sex development (TDSD) is a rare condition, characterised by a female karyotype, male phenotype, small testes and cryptorchidism. Only a few studies have investigated the genetic causes of male sex reversal. This is the clinical report of an Iranian 46,XX patient presented with TDSD and associated with hypospadias. Whole-exome sequencing (WES) of the patient ascertained the heterozygous missense variant (c.274C>T) in the NR5A1 gene, resulting in a substitution of arginine with tryptophan. The arginine 92 residue was located in a highly conserved region of steroidogenic factor 1 (SF1), which is crucial for its interaction with DNA. Our finding is in line with previous reports, which highlighted the role of p.(Arg92Trp) variant in TDSD individuals. As far as we are aware, this is the first report of TDSD with p.(Arg92Trp) variant in the Iranian population.

Analysis of variants in GATA4 and FOG2/ZFPM2 demonstrates benign contribution to 46,XY disorders of sex development

Background

GATA‐binding protein 4 (GATA4) and Friend of GATA 2 protein (FOG2, also known as ZFPM2) form a heterodimer complex that has been shown to influence transcription of genes in a number of developmental systems. Recent evidence has also shown these genes play a role in gonadal sexual differentiation in humans. Previously we identified four variants in GATA4 and an unexpectedly large number of variants in ZFPM2 in a cohort of individuals with 46,XY Differences/Disorders of Sex Development (DSD) (Eggers et al, Genome Biology, 2016; 17: 243).

Method

Here, we review variant curation and test the functional activity of GATA4 and ZFPM2 variants. We assess variant transcriptional activity on gonadal specific promoters (Sox9 and AMH) and variant protein–protein interactions.

Results

Our findings support that the majority of GATA4 and ZFPM2 variants we identified are benign in their contribution to 46,XY DSD. Indeed, only one variant, in the conserved N‐terminal zinc finger of GATA4, was considered pathogenic, with functional analysis confirming differences in its ability to regulate Sox9 and AMH and in protein interaction with ZFPM2.

Conclusions

Our study helps define the genetic factors contributing to 46,XY DSD and suggests that the majority of variants we identified in GATA4 and ZFPM2/FOG2 are not causative.

Translating genomics to the clinical diagnosis of disorders/differences of sex development

The medical and psychosocial challenges faced by patients living with Disorders/Differences of Sex Development (DSD) and their families can be alleviated by a rapid and accurate diagnostic process. Clinical diagnosis of DSD is limited by a lack of standardization of anatomical and endocrine phenotyping and genetic testing, as well as poor genotype/phenotype correlation. Historically, DSD genes have been identified through positional cloning of disease-associated variants segregating in families and validation of candidates in animal and in vitro modeling of variant pathogenicity. Owing to the complexity of conditions grouped under DSD, genome-wide scanning methods are better suited for identifying disease causing gene variant(s) and providing a clinical diagnosis. Here, we review a number of established genomic tools (karyotyping, chromosomal microarrays and exome sequencing) used in clinic for DSD diagnosis, as well as emerging genomic technologies such as whole-genome (short-read) sequencing, long-read sequencing, and optical mapping used for novel DSD gene discovery. These, together with gene expression and epigenetic studies can potentiate the clinical diagnosis of DSD diagnostic rates and enhance the outcomes for patients and families.

Development of the human penis and clitoris

The human penis and clitoris develop from the ambisexual genital tubercle. To compare and contrast the development of human penis and clitoris, we used macroscopic photography, optical projection tomography, light sheet microscopy, scanning electron microscopy, histology and immunohistochemistry. The human genital tubercle differentiates into a penis under the influence of androgens forming a tubular urethra that develops by canalization of the urethral plate to form a wide diamond-shaped urethral groove (opening zipper) whose edges (urethral folds) fuse in the midline (closing zipper). In contrast, in females, without the influence of androgens, the vestibular plate (homologue of the urethral plate) undergoes canalization to form a wide vestibular groove whose edges (vestibular folds) remain unfused, ultimately forming the labia minora defining the vaginal vestibule. The neurovascular anatomy is similar in both the developing human penis and clitoris and is the key to successful surgical reconstructions.

Prostatic adenocarcinoma in the setting of persistent müllerian duct syndrome: a case report

Persistent müllerian duct syndrome (PMDS) is a form of disordered sex development in which rudimentary müllerian structures are identified in phenotypically and genotypically normal males. It is caused by defects in the anti-müllerian hormone (AMH) system. Since patients with PMDS present with undescended testes, testosterone production by Leydig cells later in life is often decreased. The role of androgens in prostate cancerogenesis is well known. Cryptorchid testes and diminished testosterone levels in post-pubertal life in patients with PMDS play a protective role against prostate cancer, and hence, prostate cancer is a rare event in patients with PMDS. Herein, we present a patient who underwent prostatectomy for high-grade prostatic adenocarcinoma with persistent müllerian structures (such as rudimentary uterus, fallopian tubes, and cervix) identified during surgery. To our knowledge, this is the second case reported in the English language literature where PMDS was associated with prostate cancer.

Disorders of sex development: insights from targeted gene sequencing of a large international patient cohort

Background

Disorders of sex development (DSD) are congenital conditions in which chromosomal, gonadal, or phenotypic sex is atypical. Clinical management of DSD is often difficult and currently only 13% of patients receive an accurate clinical genetic diagnosis. To address this we have developed a massively parallel sequencing targeted DSD gene panel which allows us to sequence all 64 known diagnostic DSD genes and candidate genes simultaneously.

Results

We analyzed DNA from the largest reported international cohort of patients with DSD (278 patients with 46,XY DSD and 48 with 46,XX DSD). Our targeted gene panel compares favorably with other sequencing platforms. We found a total of 28 diagnostic genes that are implicated in DSD, highlighting the genetic spectrum of this disorder. Sequencing revealed 93 previously unreported DSD gene variants. Overall, we identified a likely genetic diagnosis in 43% of patients with 46,XY DSD. In patients with 46,XY disorders of androgen synthesis and action the genetic diagnosis rate reached 60%. Surprisingly, little difference in diagnostic rate was observed between singletons and trios. In many cases our findings are informative as to the likely cause of the DSD, which will facilitate clinical management.

Conclusions

Our massively parallel sequencing targeted DSD gene panel represents an economical means of improving the genetic diagnostic capability for patients affected by DSD. Implementation of this panel in a large cohort of patients has expanded our understanding of the underlying genetic etiology of DSD. The inclusion of research candidate genes also provides an invaluable resource for future identification of novel genes.

Electronic supplementary material

The online version of this article (doi:10.1186/s13059-016-1105-y) contains supplementary material, which is available to authorized users.

Presence of Germ Cells in Disorders of Sex Development: Implications for Fertility Potential and Preservation

PURPOSE

We sought to determine the presence of germ cells in the gonads of patients with disorders of sex development to establish whether preservation of germ cells for future fertility potential is possible. We hypothesized that germ cells are present but vary by age and diagnosis.

MATERIALS AND METHODS

We reviewed histology from patients with disorders of sex development who underwent gonadectomy/biopsy from 2002 to 2014 at a single institution for pathological classification of the gonad, composition of gonadal stroma and germ cell presence.

RESULTS

A total of 44 patients were identified and germ cells were present in 68%. The presence and average number of germ cells per mm² were analyzed by gonad type and diagnosis. By gonad type all ovotestes, most testes, ovaries and dysgenetic testes, and 15% of streak gonads had germ cells present. By diagnosis germ cells were present in all patients with complete androgen insensitivity syndrome, Denys-Drash syndrome, SRY mutation, mixed gonadal dysgenesis, ovotesticular conditions and StAR (steroid acute regulatory protein) deficiency, in some patients with persistent müllerian duct syndrome, XO/XY Turner syndrome and disorders of sex development not otherwise specified, and in none with complete or partial gonadal dysgenesis. Germ cells were present in the gonads of 88% of patients 0 to 3 years old, 50% of those 4 to 11 years old and 43% of those older than 12 years.

CONCLUSIONS

Germ cells were present in the majority of our cohort and the presence decreased with age. This novel, fertility driven evaluation of germ cell quantity in a variety of disorders of sex development suggests that fertility potential may be greater than previously thought. Further studies must be done to evaluate a larger population and examine germ cell quality to determine the viability of these germ cells.

Using ROADMAP Data to Identify Enhancers Associated with Disorders of Sex Development

Despite recent advances in our understanding, most cases of disorders of sex development (DSD) cannot be explained by mutations in known genes. In genome-wide screens of DSD patients, we and others detected duplications or deletions of potential regulatory regions of known or suspected DSD genes. It is therefore likely that a significant proportion of DSD cases may be explained by disrupted transcriptional regulation of gonad genes. Despite many recent technological advances, limited availability of relevant tissues - especially human embryonic material - can make the identification of long-range regulatory elements extremely difficult. In an attempt to overcome this limitation, we evaluated the usefulness of publicly available DNaseI hypersensitivity data from the Roadmap Epigenomics Project. For this feasibility study we used the 'gene desert' around the SOX9 gene and a genomic locus downstream of GATA4. Over 60% of our selected candidate regions had significant enhancer activity in luciferase assays. We show that this approach facilitates the detection of strong enhancer candidates worthy of further analysis.

Genetic Analyses Reveal Functions for MAP2K3 and MAP2K6 in Mouse Testis Determination

Testis determination in mammals is initiated by expression of SRY in somatic cells of the embryonic gonad. Genetic analyses in the mouse have revealed a requirement for mitogen-activated protein kinase (MAPK) signaling in testis determination: targeted loss of the kinases MAP3K4 and p38 MAPK causes complete XY embryonic gonadal sex reversal. These kinases occupy positions at the top and bottom level, respectively, in the canonical threetier MAPK-signaling cascade: MAP3K, MAP2K, MAPK. To date, no role in sex determination has been attributed to a MAP2K, although such a function is predicted to exist. Here, we report roles for the kinases MAP2K3 and MAP2K6 in testis determination. C57BL/6J (B6) embryos lacking MAP2K3 exhibited no significant abnormalities of testis development, whilst those lacking MAP2K6 exhibited a minor delay in testis determination. Compound mutants lacking three out of four functional alleles at the two loci also exhibited delayed testis determination and transient ovotestis formation as a consequence, suggestive of partially redundant roles for these kinases in testis determination. Early lethality of double-knockout embryos precludes analysis of sexual development. To reveal their roles in testis determination more clearly, we generated Map2k mutant B6 embryos using a weaker Sry allele (Sry^AKR). Loss of Map2k3 on this highly sensitized background exacerbates ovotestis development, whilst loss of Map2k6 results in complete XY gonadal sex reversal associated with reduction of Sry expression at 11.25 days postcoitum. Our data suggest that MAP2K6 functions in mouse testis determination, via positive effects on Sry, and also indicate a minor role for MAP2K3.

Gonadal Identity in the Absence of Pro-Testis Factor SOX9 and Pro-Ovary Factor Beta-Catenin in Mice

Sex-reversal cases in humans and genetic models in mice have revealed that the fate of the bipotential gonad hinges upon the balance between pro-testis SOX9 and pro-ovary beta-catenin pathways. Our central query was: if SOX9 and beta-catenin define the gonad's identity, then what do the gonads become when both factors are absent? To answer this question, we developed mouse models that lack either Sox9, beta-catenin, or both in the somatic cells of the fetal gonads and examined the morphological outcomes and transcriptome profiles. In the absence of Sox9 and beta-catenin, both XX and XY gonads progressively lean toward the testis fate, indicating that expression of certain pro-testis genes requires the repression of the beta-catenin pathway, rather than a direct activation by SOX9. We also observed that XY double knockout gonads were more masculinized than their XX counterpart. To identify the genes responsible for the initial events of masculinization and to determine how the genetic context (XX vs. XY) affects this process, we compared the transcriptomes of Sox9/beta-catenin mutant gonads and found that early molecular changes underlying the XY-specific masculinization involve the expression of Sry and 21 SRY direct target genes, such as Sox8 and Cyp26b1. These results imply that when both Sox9 and beta-catenin are absent, Sry is capable of activating other pro-testis genes and drive testis differentiation. Our findings not only provide insight into the mechanism of sex determination, but also identify candidate genes that are potentially involved in disorders of sex development.

Genome-wide identification of CBX2 targets: insights in the human sex development network

Chromobox homolog 2 (CBX2) is a chromatin modifier that plays an important role in sexual development and its disorders (disorders of sex development [DSD]), yet the exact rank and function of human CBX2 in this pathway remains unclear. Here, we performed large-scale mapping and analysis of in vivo target loci of the protein CBX2 in Sertoli-like NT-2D1 cells, using the DNA adenine methyltransferase identification technique. We identified close to 1600 direct targets for CBX2. Intriguingly, validation of selected candidate genes using qRT-PCR in cells overexpressing CBX2 or in which CBX2 has been knocked down indicated that several CBX2-responsive genes encode proteins that are involved in DSD. We further validated these effects on the candidate genes using a mutated CBX2 causing DSD in human patient. Overall, our findings suggest that CBX2 role in the sex development cascade is to stimulate the male pathway and concurrently inhibit the female pathway. These data provide fundamental insights into potential etiology of DSD.

Management of disorders of sex development

The medical term disorders of sex development (DSDs) is used to describe individuals with an atypical composition of chromosomal, gonadal and phenotypic sex, which leads to differences in the development of the urogenital tract and reproductive system. A variety of genetic factors have been identified that affect sex development during gonadal differentiation or in specific disorders associated with altered androgen biosynthesis or action. The diagnosis of DSDs in individuals and the subsequent management of patients and their families requires a targeted and structured approach, involving a multidisciplinary team with effective communication between the disciplines. This approach includes distinct clinical, imaging, laboratory and genetic evaluations of patients with DSDs. Although treatment of patients with DSDs can include endocrine and surgical options, many patients have concerns that arise from past incorrect treatments that were founded on the traditional binary concept of the sexes. To dispel these concerns, it is necessary to create centres of expertise for DSDs that include physicians, surgeons, psychologists and specialists in diagnostic procedures to manage patients and their families. Additionally, the inclusion of trained peer support in the multidisciplinary DSD team seems to be integral to the supportive management of patients with DSDs. Most importantly, dealing with DSDs requires acceptance of the fact that deviation from the traditional definitions of gender is not necessarily pathologic.