Genetic approach to ambiguous genitalia and disorders of sex development: What clinicians need to know

Discrepancies Between Sex Prediction and Fetal Sex After Prenatal Noninvasive Cell-Free DNA Screening

In the last 10 years the field of prenatal diagnosis has been significantly reshaped followed by the implementation of noninvasive prenatal cell-free DNA (cfDNA) testing methodologies in clinical practice. Based on a superior performance and higher sensitivity and specificity than the former practice of biochemical markers screening, the American College of Obstetricians and Gynecologists and American College of Medical Genetics and Genomics recommend noninvasive prenatal cfDNA screening for trisomy 21, 18, 13, and sex chromosome aneuploidy to all pregnant people. While cfDNA screening is helpful in risk assessment for the most common autosomal trisomies, cfDNA also provides information about fetal sex chromosomes. Prediction of fetal sex is highly desired by the parents and also useful to healthcare providers for management of pregnancies that are at-risk for X-linked conditions. In fact, utilization of cfDNA screening has resulted in a significant number of referrals to evaluate discordant results for cfDNA sex prediction and appearance of fetal genitalia by prenatal ultrasound scan or at birth raising concerns about the fetus/infant atypical sex development known as a difference in sex development (DSD). In this mini-review, we outline principles and limitations of cfDNA technology, summarize recent findings related to cfDNA test performance in prediction of sex chromosome abnormalities and DSD conditions, define the technical and biological causes of discrepant results, provide recommendations to consolidate efforts by prenatal and clinical management teams in challenging situations, and discuss ethical considerations associated with fetal sex prediction and prenatal DSD diagnosis.

Sex Assignment in Cases of Ambiguous Genitalia

Ambiguous genitalia is a rare disorder where it is unclear whether an infant's external genitals are male or female. This can be attributed to various internal and external etiologies, such as androgen receptor abnormalities, gonadal abnormalities (such as gonadal dysgenesis or Klinefelter syndrome where a male has an extra X chromosome), enzymatic defects, etc. Correction of such atypical genitalia requires a multidisciplinary approach, including but not limited to surgeons and therapists. It is important to keep in mind that the treatment plan is tailored according to the specific etiology that is causative of the patient's condition, along with the anticipated perioperative and postoperative complications. Islamically speaking, this topic has been addressed in various Islamic literature and disciplines, including guidelines for dealing with this medical condition. Moreover, follow-up of the patient must be done to allow smooth integration into society.

Application and insights of targeted next-generation sequencing in a large cohort of 46,XY disorders of sex development in Chinese

PURPOSE

46,XY disorders of sex development (46,XY DSD) are characterized by incomplete masculinization of genitalia with reduced androgenization. Accurate clinical management remains challenging, especially based solely on physical examination. Targeted next-generation sequencing (NGS) with known pathogenic genes provides a powerful tool for diagnosis efficiency. This study aims to identify the prevalent genetic variants by targeted NGS technology and investigate the diagnostic rate in a large cohort of 46,XY DSD patients, with most of them presenting atypical phenotypes.

METHODS

Two different DSD panels were developed for sequencing purposes, targeting a cohort of 402 patients diagnosed with 46,XY DSD, who were recruited from the Department of Urology at Children's Hospital, Zhejiang University School of Medicine (Hangzhou, China). The detailed clinical characteristics were evaluated, and peripheral blood was collected for targeted panels to find the patients' variants. The clinical significance of these variants was annotated according to American College of Medical Genetics and Genomics (ACMG) guidelines.

RESULTS

A total of 108 variants across 42 genes were found in 107 patients, including 46 pathogenic or likely pathogenic variants, with 45.7%(21/46) being novel. Among these genes, SRD5A2, AR, FGFR1, LHCGR, NR5A1, CHD7 were the most frequently observed. Besides, we also detected some uncommon causative genes like SOS1, and GNAS. Oligogenic variants were also identified in 9 patients, including several combinations PROKR2/FGFR1/CYP11B1, PROKR2/ATRX, PROKR2/AR, FGFR1/LHCGR/POR, FGFR1/NR5A1, GATA4/NR5A1, WNT4/AR, MAP3K1/FOXL2, WNT4/AR, and SOS1/FOXL2.

CONCLUSION

The overall genetic diagnostic rate was 11.2%(45/402), with an additional 15.4% (62/402) having variants of uncertain significance. Additionally, trio/duo patients had a higher genetic diagnostic rate (13.4%) compared to singletons (8.6%), with a higher proportion of singletons (15.1%) presenting variants of uncertain significance. In conclusion, targeted gene panels identified pathogenic variants in a Chinese 46,XY DSD cohort, expanding the genetic understanding and providing evidence for known pathogenic genes' involvement.

Cytogenomic description of a Mexican cohort with differences in sex development

BACKGROUND

Differences in Sex Development (DSD) is a heterogeneous group of congenital alterations that affect inner and/or outer primary sex characters. Although these conditions do not represent a mortality risk, they can have a severe psycho-emotional impact if not appropriately managed. The genetic changes that can give rise to DSD are diverse, from chromosomal alterations to single base variants involved in the sexual development network. Epidemiological studies about DSD indicate a global frequency of 1:4500-5500, which can increase to 1:200-300, including isolated anatomical defects. To our knowledge, this study is the first to describe epidemiological and genetic features of DSD in a cohort of Mexican patients of a third-level care hospital.

METHODS

Descriptive and retrospective cross-sectional study that analyzed DSD patients from 2015 to 2021 attended a Paediatric Hospital from Mexico City.

RESULTS

One hundred one patients diagnosed with DSD were registered and grouped into different entities according to the Chicago consensus statement and the diagnosis defined by the multidisciplinary group. Of the total, 54% of them belong to the chromosomal DSD classification, 16% belongs to 46, XX and 30% of them belongs to the 46, XY classification.

CONCLUSION

The frequency for chromosomal DSDs was consistent with the literature; however, we found that DSD 46, XY is more frequent in our cohort, which may be due to the age of the patients captured, the characteristics of our study population, or other causes that depend on the sample size.

New molecular insights into the A218V variant impact on the steroidogenic acute regulatory protein (STAR) associated with 46, XY disorders of sexual development

Disorders of sexual development (DSD) are an abnormal congenital conditions associated with atypical development of the urogenital tract and external genital structures. The steroidogenic acute regulatory (STAR) gene, associated with congenital lipoid adrenal hyperplasia (CLAH), is included in the targeted gene panel for the DSD diagnosis. Therefore, the genetic alterations of the STAR gene and their molecular effect were examined in the CLAH patients affected with DSD. Ten different Iranian families including twelve male pseudo-hermaphroditism patients with CLAH phenotype were studied using genetic linkage screening and STAR gene sequencing in the linked families to the STAR locus. Furthermore, the structural, dynamical, and functional impacts of the variants on the STAR in silico were analyzed. Sanger sequencing showed the pathogenic variant p.A218V in STAR gene, as the first report in Iranian population. Moreover, modeling and simulation analysis were performed using tools such as radius of gyration, root mean square deviation (RMSD), root mean square fluctuation (RMSF), and molecular docking showed that p.A218V variant affects the residues interaction in cholesterol-binding site and the proper folding of STAR through increasing H-bound and the amount of α-Helix, deceasing total flexibility and changing fluctuations in some residues, resulting in reduced steroidogenic activity of the STAR protein. The study characterized the structural and functional changes of STAR caused by pathogenic variant p.A218V. It leads to limited cholesterol-binding activity of STAR, ultimately leading to the CLAH disease. Molecular dynamics simulation of STAR variants could help explain different clinical manifestations of CLAH disease.

Construction of Copy Number Variation Map Identifies Small Regions of Overlap and Candidate Genes for Atypical Female Genitalia Development

Copy number variations (CNVs) have been implicated in various conditions of differences of sexual development (DSD). Generally, larger genomic aberrations are more often considered disease-causing or clinically relevant, but over time, smaller CNVs have been associated with various forms of DSD. The main objective of this study is to identify small CNVs and the smallest regions of overlap (SROs) in patients with atypical female genitalia (AFG) and build a CNV map of AFG. We queried the DECIPHER database for recurrent duplications and/or deletions detected across the genome of AFG individuals. From these data, we constructed a chromosome map consisting of SROs and investigated such regions for genes that may be associated with the development of atypical female genitalia. Our study identified 180 unique SROs (7.95 kb to 45.34 Mb) distributed among 22 chromosomes. The most SROs were found in chromosomes X, 17, 11, and 22. None were found in chromosome 3. From these SROs, we identified 22 genes as potential candidates. Although none of these genes are currently associated with AFG, a literature review indicated that almost half were potentially involved in the development and/or function of the reproductive system, and only one gene was associated with a disorder that reported an individual patient with ambiguous genitalia. Our data regarding novel SROs requires further functional investigation to determine the role of the identified candidate genes in the development of atypical female genitalia, and this paper should serve as a catalyst for downstream molecular studies that may eventually affect the genetic counseling, diagnosis, and management of these DSD patients.

Differences of Sex Development: What Neonatologists Need to Know

Differences of sex development (DSD) refer to rare conditions in which an individual's sex development is different from typical male or female development. The neonatologist is often the first health care provider to interact with parents of newborns with DSD and must be familiar with the approach to patients with DSD. In this article, we discuss definition of DSD, initial workup of the patient with DSD, terminology, and controversies in care.

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.

El laboratorio en el diagnóstico multidisciplinar del desarrollo sexual anómalo o diferente (DSD)

Objetivos

El desarrollo de las características sexuales femeninas o masculinas acontece durante la vida fetal, determinándose el sexo genético, el gonadal y el sexo genital interno y externo (femenino o masculino). Cualquier discordancia en las etapas de diferenciación ocasiona un desarrollo sexual anómalo o diferente (DSD) que se clasifica según la composición de los cromosomas sexuales del cariotipo.

Contenido

En este capítulo se abordan la fisiología de la determinación y el desarrollo de las características sexuales femeninas o masculinas durante la vida fetal, la clasificación general de los DSD y su estudio diagnóstico clínico, bioquímico y genético que debe ser multidisciplinar. Los estudios bioquímicos deben incluir, además de las determinaciones bioquímicas generales, análisis de hormonas esteroideas y peptídicas, en condiciones basales o en pruebas funcionales de estimulación. El estudio genético debe comenzar con la determinación del cariotipo al que seguirá un estudio molecular en los cariotipos 46,XX ó 46,XY, orientado a la caracterización de un gen candidato. Además, se expondrán de manera específica los marcadores bioquímicos y genéticos en los DSD 46,XX, que incluyen el desarrollo gonadal anómalo (disgenesias, ovotestes y testes), el exceso de andrógenos de origen fetal (el más frecuente), fetoplacentario o materno y las anomalías del desarrollo de los genitales internos.

Perspectivas

El diagnóstico de un DSD requiere la contribución de un equipo multidisciplinar coordinado por un clínico y que incluya los servicios de bioquímica y genética clínica y molecular, un servicio de radiología e imagen y un servicio de anatomía patológica.

The laboratory in the multidisciplinary diagnosis of differences or disorders of sex development (DSD): III) Biochemical and genetic markers in the 46,XYIV) Proposals for the differential diagnosis of DSD

Objectives

46,XY differences/disorders of sex development (DSD) involve an abnormal gonadal and/or genital (external and/or internal) development caused by lack or incomplete intrauterine virilization, with or without the presence of Müllerian ducts remnants.

Content

Useful biochemical markers for differential diagnosis of 46,XY DSD include hypothalamic-pituitary-gonadal hormones such as luteinizing and follicle-stimulating hormones (LH and FSH; in baseline or after LHRH stimulation conditions), the anti-Müllerian hormone (AMH), inhibin B, insulin-like 3 (INSL3), adrenal and gonadal steroid hormones (including cortisol, aldosterone, testosterone and their precursors, dihydrotestosterone and estradiol) and the pituitary ACTH hormone. Steroid hormones are measured at baseline or after stimulation with ACTH (adrenal hormones) and/or with HCG (gonadal hormones).

Summary

Different patterns of hormone profiles depend on the etiology and the severity of the underlying disorder and the age of the patient at diagnosis. Molecular diagnosis includes detection of gene dosage or copy number variations, analysis of candidate genes or high-throughput DNA sequencing of panels of candidate genes or the whole exome or genome.

Outlook

Differential diagnosis of 46,XX or 46,XY DSD requires a multidisciplinary approach, including patient history and clinical, morphological, imaging, biochemical and genetic data. We propose a diagnostic algorithm suitable for a newborn with DSD that focuses mainly on biochemical and genetic data.

The laboratory in the multidisciplinary diagnosis of differences or disorders of sex development (DSD): I) Physiology, classification, approach, and methodologyII) Biochemical and genetic markers in 46,XX DSD

Objectives

The development of female or male sex characteristics occurs during fetal life, when the genetic, gonadal, and internal and external genital sex is determined (female or male). Any discordance among sex determination and differentiation stages results in differences/disorders of sex development (DSD), which are classified based on the sex chromosomes found on the karyotype.

Content

This chapter addresses the physiological mechanisms that determine the development of female or male sex characteristics during fetal life, provides a general classification of DSD, and offers guidance for clinical, biochemical, and genetic diagnosis, which must be established by a multidisciplinary team. Biochemical studies should include general biochemistry, steroid and peptide hormone testing either at baseline or by stimulation testing. The genetic study should start with the determination of the karyotype, followed by a molecular study of the 46,XX or 46,XY karyotypes for the identification of candidate genes.

Summary

46,XX DSD include an abnormal gonadal development (dysgenesis, ovotestes, or testes), an androgen excess (the most frequent) of fetal, fetoplacental, or maternal origin and an abnormal development of the internal genitalia. Biochemical and genetic markers are specific for each group.

Outlook

Diagnosis of DSD requires the involvement of a multidisciplinary team coordinated by a clinician, including a service of biochemistry, clinical, and molecular genetic testing, radiology and imaging, and a service of pathological anatomy.

El laboratorio en el diagnóstico multidisciplinar del desarrollo sexual anómalo o diferente (DSD): III) Marcadores bioquímicos y genéticos en los 46,XY IV) Propuestas para el diagnóstico diferencial de los DSD

Objetivos

El desarrollo sexual anómalo o diferente (DSD) con cariotipo 46,XY incluye anomalías en el desarrollo gonadal y/o genital (externo y/o interno).

Contenido

Los marcadores bioquímicos útiles para el diagnóstico diferencial de los DSD con cariotipo 46,XY incluyen las hormonas del eje hipotálamo-hipófiso gonadal como son las gonadotropinas LH y FSH (en condiciones basales o tras la estimulación con LHRH), la hormona anti-Mülleriana, la inhibina B, el factor insulinoide tipo 3 y las hormonas esteroideas de origen suprarrenal (se incluirá la hormona hipofisaria ACTH) y testicular (cortisol, aldosterona y sus precursores, testosterona y sus precursores, dihidrotestosterona y estradiol). Las hormonas esteroideas se analizarán en condiciones basales o tras la estimulación con ACTH (hormonas adrenales) y/o con HCG (hormonas testiculares). Los patrones de variación de las distintas hormonas dependerán de la causa y la edad de cada paciente. El diagnóstico molecular debe incluir el análisis de un gen candidato, un panel de genes o el análisis de un exoma completo.

Perspectivas

El diagnóstico diferencial de los DSD con cariotipos 46,XX ó 46,XY debe ser multidisciplinar, incluyendo los antecedentes clínicos, morfológicos, de imagen, bioquímicos y genéticos. Se han elaborado numerosos algoritmos diagnósticos.

Differences of sex development in the newborn: from clinical scenario to molecular diagnosis

Differences/disorders of sex development (DSD) are defined as a group of congenital conditions in which the development of chromosomal, gonadal or anatomical sex is atypical. The incidence of DSD is 1:4500 births. The current classification divides DSDs into 3 categories according to chromosomal sex: 46,XX DSD, 46,XY DSD and sex chromosome DSD. DSD phenotypes can be concordant with the genotype (apparently normal external genitalia associated with gonadal dysgenesis), or can range from simply hypospadias to completely masculinised or feminised genitalia with a discordant karyotype. Numerous genes implicated in genital development have been reported. The search of genetic variants represents a central element of the extended investigation, as an improved knowledge of the genetic aetiology helps the immediate and long-term management of children with DSDs, in term of sex of rearing, hormone therapy, surgery, fertility and cancer risk. This review aims to assess the current role of molecular diagnosis in DSD management.

Chromosome Abnormalities Related to Reproductive and Sexual Development Disorders: A 5-Year Retrospective Study

Chromosomal abnormalities are the main genetic risk factor associated with reproductive and sexual development disorders (DSD). The goal of this study is to retrospectively evaluate the frequency of chromosomal aberrations in Moroccan subjects with problems of procreation or sexual ambiguity. A total of 1005 individuals, including 170 infertile couples, underwent cytogenetic analysis in the Cytogenetic Laboratory of the Pasteur Institute of Morocco. Heparinized blood samples were processed according to the standard karyotype method. A total (81.5%) of the patients studied had a normal karyotype, while the remaining (18.5%) patients had an abnormal karyotype. Female patients had more chromosomal abnormalities (52%) than male patients (48%). These chromosomal aberrations included 154 cases (83%) of sex chromosomal abnormalities, the most common being Turner's syndrome and Klinefelter's syndrome, and 31 cases (17%) had autosomal aberrations, especially chromosome 9 reversal (inv(9)(p12;q13)). The present data shows that among 170 couples, 10.6% had chromosomal abnormalities mainly involved in the occurrence of recurrent miscarriages. Genotype-phenotype correlations could not be made, and therefore, studies using more resolutive molecular biology techniques would be desirable.

Neurobiology of puberty and its disorders

Puberty, which in humans is considered to include both gonadarche and adrenarche, is the period of becoming capable of reproducing sexually and is recognized by maturation of the gonads and development of secondary sex characteristics. Gonadarche referring to growth and maturation of the gonads is fundamental to puberty since it encompasses increased gonadal steroid secretion and initiation of gametogenesis resulting from enhanced pituitary gonadotropin secretion, triggered in turn by robust pulsatile GnRH release from the hypothalamus. This chapter reviews the development of GnRH pulsatility from before birth until the onset of puberty. In humans, GnRH pulse generation is restrained during childhood and juvenile development. This prepubertal hiatus in hypothalamic activity is considered to result from a neurobiological brake imposed upon the GnRH pulse generator resident in the infundibular nucleus. Reactivation of the GnRH pulse generator initiates pubertal development. Current understanding of the genetics and physiology of the brake will be discussed, as will hypotheses proposed to account for timing the resurgence in pulsatile GnRH and initiation of puberty. The chapter ends with a discussion of disorders associated with precocious or delayed puberty with a focus on those with etiologies attributed to aberrant GnRH neuron anatomy or function. A pediatric approach to patients with pubertal disorders is provided and contemporary treatments for both precocious and delayed puberty outlined.

Individualized care for patients with intersex (disorders/differences of sex development): part I

The care of individuals with disorders/differences of sex development aims to enable affected individuals and their families to have the best quality of life, particularly those born with severe genital ambiguity. Two of the biggest concerns for parents and health professionals are: (1) making a gender assignment and (2) the decisions of whether or not surgery is indicated, and if so, when is best for the patient and parents. These decisions, which can be overwhelming to families, are almost always made in the face of uncertainties. Such decisions must involve the parents, include multidisciplinary contributions, have an underlying principle of full disclosure, and respect familial, philosophical, and cultural values. Assignment as male or female is made with the realization that gender identity cannot be predicted with certainty. Because of the variability among those with the same diagnosis and complexity of phenotype-genotype correlation, the use of algorithms is inappropriate. The goal of this article is to emphasize the need for individualized care to make the best possible decisions for each patient's unique situation.

The Natural History of a Man With Ovotesticular 46,XX DSD Caused by a Novel 3-Mb 15q26.2 Deletion Containing NR2F2 Gene

Gonadal sex determination is a complex genetic process by which an embryonic primordium is driven to form an ovary or a testis, which requires a delicate dosage balance involving many genes. Disruption in this molecular pathway can lead to differences of sex development (DSD). Although some genetic mechanisms leading to 46,XY DSD have been elucidated, little is known about copy-number variation (CNV) causing testicular or ovotesticular 46,XX DSD. We describe a 20-year natural history of a man with SRY-negative 46,XX who was born with atypical male external genitalia, aortic coarctation, and bilateral blepharophimosis-ptosis. The molecular study identified a de novo heterozygous 3-Mb 15q26.2 deletion, a gene-poor locus containing NR2F2, which encodes the nuclear receptor COUP-TFII that is highly expressed in ovary and cardiac arteries. Immunohistochemistry confirmed the low COUP-TFII expression on his ovotestis tissue. Monosomy of 15q26.2, encompassing the NR2F2 gene, may act as a Z-factor regulating the male sex determination negatively. This finding supports a novel type of CNV resulting in DSD in an individual who developed male puberty spontaneously.

Evaluation of ambiguous genitalia

PURPOSE OF REVIEW

To provide a framework for the evaluation of ambiguous genitalia.

RECENT FINDINGS

The most pressing evaluation of ambiguous genitalia is assessment for life-threatening causes such as salt-wasting congenital adrenal hyperplasia (CAH) or syndromes with underlying anomalies such as neurologic or cardiac malformations. A multidisciplinary team, including specialists in Gynecology, Endocrinology, Urology, Genetics, Clinical Psychology/Psychiatry, Radiology, Nursing, Neonatology, and Pediatric Surgery, should be involved. Each patient should be approached in an individualized manner to assign sex of rearing in the most expeditious yet thoughtful means possible.As knowledge on the natural history of sex preference and fertility of individuals with ambiguous genitalia increases, controversy regarding the indication for and timing of genital surgery continues. Considerations include gender identity, future fertility, malignancy risk, infection prevention, and functional anatomy for sexual activity.

SUMMARY

The evaluation of ambiguous genitalia should involve a multidisciplinary team. A combination of history taking, physical examination, laboratory evaluation, and radiologic assessment can assist with the diagnosis. Care should be taken to emphasize karyotypic sex is not equivalent to gender and to use caution with regards to irreversible medical and surgical therapies which may impact fertility and sexual function and nonconform with future sex identity.

Early Bilateral Gonadoblastoma Associated With 45,X/46,XY Mosaicism: The Spectrum of Undifferentiated Gonadal Tissue and Gonadoblastoma in the First Months of Life

45,X/46,XY mosaicism is one of a heterogenous group of congenital conditions known as differences (disorders) of sex development (DSD) that results in abnormal development of internal and external genitalia. Patients with DSD, particularly those with segments of the Y chromosome, are at increased risk for germ cell tumors including gonadoblastoma. Gonadoblastoma is a neoplasm comprised of a mixture of germ cells and elements resembling immature granulosa or Sertoli cells with or without Leydig cells or lutein-type cells in an ovarian type stroma. Gonadoblastoma has an increased prevalence of 15% to 40% in patients with 45,X/46,XY mosaicism and has been previously reported in patients as young as 5 months of age with that karyotype. Herein, we describe a 3-month-old child with 45,X/46,XY karyotype who was referred for the evaluation of asymmetric labia majora. Additional evaluation revealed left streak gonad and right dysplastic/dysgenetic testis. Both gonads contained foci of cells typical for gonadoblastoma as well as undifferentiated gonadal tissue, underscoring the potential for very early infantile gonadoblastoma and the spectrum of developmental anomalies associated with this karyotype.

A clinical algorithm to diagnose differences of sex development

The diagnosis and management of children born with ambiguous genitalia is challenging for clinicians. Such differences of sex development (DSDs) are congenital conditions in which chromosomal, gonadal, or anatomical sex is atypical. The aetiology of DSDs is very heterogenous and a precise diagnosis is essential for management of genetic, endocrine, surgical, reproductive, and psychosocial issues. In this Review, we outline a step-by-step approach, compiled in a diagnostic algorithm, for the clinical assessment and molecular diagnosis of a patient with ambiguity of the external genitalia on initial presentation. We appraise established and emerging technologies and their effect on diagnosis, and discuss current controversies.

GENETICS IN ENDOCRINOLOGY: Approaches to molecular genetic diagnosis in the management of differences/disorders of sex development (DSD): position paper of EU COST Action BM 1303 ‘DSDnet’

The differential diagnosis of differences or disorders of sex development (DSD) belongs to the most complex fields in medicine. It requires a multidisciplinary team conducting a synoptic and complementary approach consisting of thorough clinical, hormonal and genetic workups. This position paper of EU COST (European Cooperation in Science and Technology) Action BM1303 ‘DSDnet’ was written by leading experts in the field and focuses on current best practice in genetic diagnosis in DSD patients. Ascertainment of the karyotpye defines one of the three major diagnostic DSD subclasses and is therefore the mandatory initial step. Subsequently, further analyses comprise molecular studies of monogenic DSD causes or analysis of copy number variations (CNV) or both. Panels of candidate genes provide rapid and reliable results. Whole exome and genome sequencing (WES and WGS) represent valuable methodological developments that are currently in the transition from basic science to clinical routine service in the field of DSD. However, in addition to covering known DSD candidate genes, WES and WGS help to identify novel genetic causes for DSD. Diagnostic interpretation must be performed with utmost caution and needs careful scientific validation in each DSD case.

Disorders of sex development

Normal sex development depends on the precise spatio-temporal sequence and coordination of mutually antagonistic activating and repressing factors. These factors regulate the commitment of the unipotential gonad into the binary pathways governing normal sex development. Typically, the presence of the SRY gene on the Y chromosome triggers the cascade of molecular events that lead to male sex development. Disorders of sex development comprise a heterogeneous group of congenital conditions associated with atypical development of internal and external genitalia. These disorders are generally attributed to deviations from the typical progression of sex development. Disorders of sex development can be classified into several categories including chromosomal, gonadal, and anatomic abnormalities. Genetic tools such as microarray analyses and next-generation sequencing techniques have identified novel genetic variants among patients with disorders of sexual development. Most importantly, patient management needs to be individualized, especially for decisions related to sex of rearing, surgical interventions, hormone treatment, and potential for fertility preservation.

Disorders/differences of sex development (DSDs) for primary care: the approach to the infant with ambiguous genitalia

The initial management of the neonate with ambiguous genitalia can be a very stressful and anxious time for families, as well as for the general practitioner or neonatologist. A timely approach must be sensitive and attend to the psychosocial needs of the family. In addition, it must also effectively address the diagnostic dilemma that is frequently seen in the care of patients with disorders of sex development (DSDs). One great challenge is assigning a sex of rearing, which must take into account a variety of factors including the clinical, biochemical and radiologic clues as to the etiology of the atypical genitalia (AG). However, other important aspects cannot be overlooked, and these include parental and cultural views, as well as the future outlook in terms of surgery and fertility potential. Achieving optimal outcomes requires open and transparent dialogue with the family and caregivers, and should harness the resources of a multidisciplinary team. The multiple facets of this approach are outlined in this review.