The testosterone:androstenedione ratio in male undermasculinization

Serum steroid metabolite profiling by LC-MS/MS in two phenotypic male patients with HSD17B3 deficiency: Implications for hormonal diagnosis

Although 17β-hydroxysteroid dehydrogenase type 3 (HSD17B3) deficiency is diagnosed when a testosterone/androstenedione (T/A-dione) ratio after human chorionic gonadotropin (hCG) stimulation is below 0.8, this cut-off value is primarily based on hormonal data measured by conventional immunoassay (IA) in patients with feminized or ambiguous genitalia. We examined two 46,XY Japanese patients with undermasculinized genitalia including hypospadias (patient 1 and patient 2). Endocrine studies by IA showed well increased serum T value after hCG stimulation (2.91 ng/mL) and a high T/A-dione ratio (4.04) in patient 1 at 2 weeks of age and sufficiently elevated basal serum T value (2.60 ng/mL) in patient 2 at 1.5 months of age. Despite such partial androgen insensitivity syndrome-like findings, whole exome sequencing identified biallelic ″pathogenic″ or ″likely pathogenic″ variants in HSD17B3 (c .188 C>T:p.(Ala63Val) and c .194 C>T:p.(Ser65Leu) in patient 1, and c.139 A>G:p.(Met47Val) and c.672 + 1 G>A in patient 2) (NM_000197.2), and functional analysis revealed reduced HSD17B3 activities of the missense variants (∼ 43% for p.Met47Val, ∼ 14% for p.Ala63Val, and ∼ 0% for p.Ser65Leu). Thus, we investigated hCG-stimulated serum steroid metabolite profiles by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in patient 1 at 7 months of age and in patient 2 at 11 months of age as well as in five control males with idiopathic micropenis aged 1 - 8 years, and found markedly high T/A-dione ratios (12.3 in patient 1 and 5.4 in patient 2) which were, however, obviously lower than those in the control boys (25.3 - 56.1) and sufficiently increased T values comparable to those of control males. The elevated T/A-dione ratios are considered be due to the residual HSD17B3 function and the measurement by LC-MS/MS. Thus, it is recommended to establish the cut-off value for the T/A-dione ratio according to the phenotypic sex reflecting the residual function and the measurement method.

Differences of Sex Development: Current Issues and Controversies

Differences of sex development (DSD) encompass a broad range of conditions in which the development of chromosomal, gonadal, or anatomic sex is not typically male or female. Terms used to describe DSD are controversial, and continuously evolving. An individualized, multidisciplinary approach is key to both the diagnosis and management of DSD. Recent advances in DSD care include expanded genetic testing options, a more nuanced approach to gonadal management, and an emphasis on shared decision-making, particularly related to external genital surgical procedures. The timing of DSD surgery is currently being questioned and debated in both medical and advocacy/activism spheres.

Diagnostic approach in 46, XY DSD: an endocrine society of bengal (ESB) consensus statement

OBJECTIVES

46, XY difference/disorder of sex development (DSD) is a relatively uncommon group of heterogeneous disorders with varying degree of underandrogenization of male genitalia. Such patients should be approached systematically to reach an aetiological diagnosis. However, we lack, at present, a clinical practice guideline on diagnostic approach in 46, XY DSD from this part of the globe. Moreover, debate persists regarding the timing and cut-offs of different hormonal tests, performed in these cases. The consensus committee consisting of 34 highly experienced endocrinologists with interest and experience in managing DSD discussed and drafted a consensus statement on the diagnostic approach to 46, XY DSD focussing on relevant history, clinical examination, biochemical evaluation, imaging and genetic analysis.

CONTENT

The consensus was guided by systematic reviews of existing literature followed by discussion. An initial draft was prepared and distributed among the members. The members provided their scientific inputs, and all the relevant suggestions were incorporated. The final draft was approved by the committee members.

SUMMARY

The diagnostic approach in 46, XY DSD should be multidisciplinary although coordinated by an experienced endocrinologist. We recommend formal Karyotyping, even if Y chromosome material has been detected by other methods. Meticulous history taking and thorough head-to-toe examination should initially be performed with focus on external genitalia, including location of gonads. Decision regarding hormonal and other biochemical investigations should be made according to the age and interpreted according to age-appropriate norms Although LC-MS/MS is the preferred mode of steroid hormone measurements, immunoassays, which are widely available and less expensive, are acceptable alternatives. All patients with 46, XY DSD should undergo abdominopelvic ultrasonography by a trained radiologist. MRI of the abdomen and/or laparoscopy may be used to demonstrate the Mullerian structure and/or to localize the gonads. Genetic studies, which include copy number variation (CNV) or molecular testing of a candidate gene or next generation sequencing then should be ordered in a stepwise manner depending on the clinical, biochemical, hormonal, and radiological findings.

OUTLOOK

The members of the committee believe that patients with 46, XY DSD need to be approached systematically. The proposed diagnostic algorithm, provided in the consensus statement, is cost effective and when supplemented with appropriate genetic studies, may help to reach an aetiological diagnosis in majority of such cases.

Lessons from 17β-HSD3 deficiency: Clinical spectrum and complex molecular basis in Chinese patients

17β-Hydroxysteroid dehydrogenase type 3 (17β-HSD3) deficiency is rarely reported in Chinese patients with 46, XY disorders of sexual development (DSD). Seven subjects with 17β-HSD3 deficiency were identified from 206 Chinese 46, XY DSD patients using targeted next-generation sequencing (NGS). Serum AD and T levels were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS). In silico and functional studies were performed to evaluate the enzymatic activity impairment of HSD17B3 variants. A minigene assay was performed in an exonic splicing variant. Our results showed that four novel and five reported HSD17B3 variants were identified in 7 unrelated patients. The patients showed cryptic presentation during childhood and classical virilization after puberty with T/AD ratio< 0.4. A heterozygous large deletion from the 5'UTR to exon 1 was identified in a patient with a monoallelic variant of p.N130S. Although predicted to be 'likely pathogenic', only p. S232P and p. S160F drastically reduced the enzymatic activity of 17β-HSD3. A previously reported 'missense' variant c 0.277 G>A (p. E93K) was revealed to have no impact on enzyme activity but resulted in aberrant splicing of exon 3 and was reclassified as an exonic splicing variant. In our study, one nonsense, one exonic splicing, one deletion, one large deletion and five missense variants were detected in patients with 17β-HSD3 deficiency, expanding the clinical and molecular profile of this disorder. In silico analysis should be cautiously interpreted when the heredity pattern and functional study are inconsistent.

Disorder of Sex Development Due to 17-Beta-Hydroxysteroid Dehydrogenase Type 3 Deficiency: A Case Report and Review of 70 Different HSD17B3 Mutations Reported in 239 Patients

The 17-beta-hydroxysteroid dehydrogenase type 3 (17-β-HSD3) enzyme converts androstenedione to testosterone and is encoded by the HSD17B3 gene. Homozygous or compound heterozygous HSD17B3 mutations block the synthesis of testosterone in the fetal testis, resulting in a Disorder of Sex Development (DSD). We describe a child raised as a female in whom the discovery of testes in the inguinal canals led to a genetic study by whole exome sequencing (WES) and to the identification of a compound heterozygous mutation of the HSD17B3 gene (c.608C>T, p.Ala203Val, and c.645A>T, p.Glu215Asp). Furthermore, we review all HSD17B3 mutations published so far in cases of 17-β-HSD3 deficiency. A total of 70 different HSD17B3 mutations have so far been reported in 239 patients from 187 families. A total of 118 families had homozygous mutations, 63 had compound heterozygous mutations and six had undetermined genotypes. Mutations occurred in all 11 exons and were missense (55%), splice-site (29%), small deletions and insertions (7%), nonsense (5%), and multiple exon deletions and duplications (2%). Several mutations were recurrent and missense mutations at codon 80 and the splice-site mutation c.277+4A>T each represented 17% of all mutated alleles. These findings may be useful to those involved in the clinical management and genetic diagnosis of this disorder.

Contribution of Clinical and Genetic Approaches for Diagnosing 209 Index Cases With 46,XY Differences of Sex Development

CONTEXT

Massively parallel sequencing (MPS) technologies have emerged as a first-tier approach for diagnosing several pediatric genetic syndromes. However, MPS has not been systematically integrated into the diagnostic workflow along with clinical/biochemical data for diagnosing 46,XY differences of sex development (DSD).

OBJECTIVE

To analyze the contribution of phenotypic classification either alone or in association with genetic evaluations, mainly MPS, for diagnosing a large cohort of 46,XY DSD patients.

DESIGN/PATIENTS

209 nonsyndromic 46,XY DSD index cases from a Brazilian DSD center were included. Patients were initially classified into 3 subgroups according to clinical and biochemical data: gonadal dysgenesis (GD), disorders of androgen secretion/action, and DSD of unknown etiology. Molecular genetic studies were performed by Sanger sequencing and/or MPS.

RESULTS

Clinical/biochemical classification into either GD or disorders of hormone secretion/action was obtained in 68.4% of the index cases. Among these, a molecular diagnosis was obtained in 36% and 96.5%, respectively. For the remainder 31.6% classified as DSD of clinically unknown etiology, a molecular diagnosis was achieved in 31.8%. Overall, the molecular diagnosis was achieved in 59.3% of the cohort. The combination of clinical/biochemical and molecular approaches diagnosed 78.9% of the patients. Clinical/biochemical classification matched with the genetic diagnosis in all except 1 case. DHX37 and NR5A1 variants were the most frequent genetic causes among patients with GD and DSD of clinical unknown etiology, respectively.

CONCLUSIONS

The combination of clinical/biochemical with genetic approaches significantly improved the diagnosis of 46,XY DSD. MPS potentially decreases the complexity of the diagnostic workup as a first-line approach for diagnosing 46,XY DSD.

Steroid profiling using liquid chromatography mass spectrometry during adrenal vein sampling in patients with primary bilateral macronodular adrenocortical hyperplasia

INTRODUCTION

Adrenal vein sampling (AVS) is not a routine procedure in patients with primary bilateral macronodular adrenocortical hyperplasia (PBMAH), but has been used to determine lateralization of cortisol secretion in order to guide decision of unilateral adrenalectomy. Our aim was to characterize the steroid fingerprints in AVS samples of patients with PBMAH and hypercortisolism and to identify a reference hormone for AVS interpretation.

METHOD

Retrospectively, we included 17 patients with PBMAH from the German Cushing's registry who underwent AVS. 15 steroids were quantified in AVS and peripheral blood samples using LC-MS/MS. We calculated lateralization indices and conversion ratios indicative of steroidogenic enzyme activity to elucidate differences between individual adrenal steroidomes and in steroidogenic pathways.

RESULTS

Adrenal volume was negatively correlated with peripheral cortisone (r=0.62, p<0.05). 24-hour urinary free cortisol correlated positively with peripheral androgens (rDHEA=0.57, rDHEAS=0.82, rA=0.73, rT=0.54, p<0.05). DHEA was found to be a powerful reference hormone with high selectivity index, which did not correlate with serume cortisol and has a short half-life. All investigated steroids showed lateralization in single patients indicating the heterogenous steroid secretion pattern in patients with PBMAH. The ratios of corticosterone/aldosterone (catalyzed by CYP11B2), androstenedione/dehydroepiandrosterone (catalyzed by HSD3B2) and cortisone/cortisol (catalyzed by HSD11B2) in adrenal vein samples were higher in smaller adrenals (p<0.05). ARMC5 mutation carriers (n=6) showed lower androstenedione/17-hydroxyprogesterone and higher testosterone/androstenedione (p<0.05) ratios in peripheral blood, in line with lower peripheral androstenedione concentrations (p<0.05).

CONCLUSION

Steroid profiling by LC-MS/MS led us to select DHEA as a candidate reference hormone for cortisol secretion. Lateralization and different steroid ratios showed that each steroid and all three steroidogenic pathways may be affected in PBMAH patients. In patients with germline ARMC5 mutations, the androgen pathway was particularly dysregulated.

Novel mutations of the LHCGR gene in two families with 46,XY DSD causing Leydig cell hypoplasia I

PURPOSE

Leydig cell hypoplasia is a rare autosomal recessive 46,XY disorder of sexual development (DSD). It is caused by homozygous or compound heterozygous inactivating mutations in the human luteinizing hormone/chorionic gonadotropin hormone receptor (LHCGR) gene. In Leydig cell hypoplasia type I, patients are characterized by predominantly female external genitalia, which usually go unrecognized until the age of puberty.

METHODS

This study reports three patients descending from two unrelated families. We performed clinical, hormonal, histopathological, molecular, and bioinformatics studies for the studied cases.

RESULTS

All investigations suggested 46,XY DSD and Leydig cell hypoplasia. Molecular analysis showed two novel homozygous inactivating mutations (p.Glu148Ter and p.Leu104Pro) within the extracellular domain of the LHCGR gene.

CONCLUSION

Although the mutations of the LHCGR gene are distributed heterogeneously, without hotspot or recurrent mutations, about one fifth of the reported mutations worldwide have been detected in Arab patients. This is probably due to the high consanguinity rate in these populations, which increases the percentage of autosomal recessive disorders and the homozygous LHCGR gene mutations.

17β-hydroxysteroid dehydrogenase type 3 deficiency: female sex assignment and follow-up

BACKGROUND

Deficiency of 17β-hydroxysteroid dehydrogenase type 3 (17β-HSD3) is a rare autosomal recessive 46,XY disorder of sex development (DSD). It is due to pathogenetic variants in the HSD17B3 gene. Mutated genes encode an abnormal enzyme with absent or reduced ability to convert Δ4-androstenedione (Δ4-A) to testosterone (T) in the fetal testis. Affected individuals are usually raised as females and diagnosis is made at puberty, when they show virilization.

METHODS

A girl with a presumptive diagnosis of complete androgen insensitivity syndrome underwent endocrine and genetic assessment. Long-term follow-up was reported.

RESULTS

The diagnosis of 17β-HSD3 deficiency was made (stimulated T/Δ4-A ratio: 0.15; HSD17B3 gene analysis: c.277+4A>T in intron 3/c.640_645del (p.Glu214_Glu215del) in exon 9. After extensive information, parents decided to maintain female sex. Gonadal removal was performed and histological evaluation demonstrated deep fibrosis of testicular tissue. Follow-up till 8.5 years of age showed somatic and neuro-psychological development fitting with the female sex.

CONCLUSIONS

Management of a child with the rare 17β-HSD3 deficiency remains challenging. Any decision must be carefully evaluated with parents. Long-term follow-up must be warranted by a multidisciplinary DSD team to evaluate the adequacy of the choices made on quality of life in later life.

"Spectrum of 46 XY Disorders of Sex Development": A Hospital-based Cross-sectional Study

BACKGROUND

Disorders of sex development (DSD) are a wide range of relatively rare conditions having diverse pathophysiology. Identification of an underlying cause can help in treating any coexisting hormone deficiencies and can help with anticipating any other immediate or long-term health concerns.

OBJECTIVE

To study the clinical and biochemical profile of patients with 46 XY DSD along with androgen receptor (AR) gene mutation status in selected group of patients.

METHODS

A cross-sectional study was conducted after enrolling the eligible DSD patients. Thorough elicitation of history and detailed clinical examination was done. Assays for luteinizing hormone, follicle-stimulating hormone, testosterone, dihydrotestosterone, androstenedione, AMH & Inhibin B (where indicated), and human chorionic gonadotropin stimulation were done as per protocol.

RESULTS

In total, 48 patients were included in the study. Ambiguous genitalia (58.3%) followed by hypospadias (33.3%) were common presentation. Androgen biosynthetic defect were the most commonly encountered diagnosis followed by androgen insensitivity syndrome (AIS). Swyer syndrome was diagnosed in 4.2% of cases; partial gonadal dysgenesis, ovotesticular DSD, and vanishing testis syndrome contributed to 2% of cases each. Eight cases (16.7%) who presented with isolated proximal and midshaft hypospadias for whom no diagnosis was found were categorized in the "etiology unclear" group. AR gene mutation analysis designed against specific exons did not yield any results.

CONCLUSION

46 XY DSD is a heterogeneous group of patients with a varying age of presentation and a diverse clinical profile. Most patients are reared as males and maintained the same gender identity except in isolated cases. Diagnosis of AIS remains a clinical challenge as a definite hormonal criterion does not exist and genetic mutations in AR gene may be negative. Flanking region sequencing, whole genome sequencing, and promoter region sequencing may reveal pathogenic variants. Variations in other genes regulating AR pathway may also be candidates to be studied.

Serum Anti-Müllerian Hormone in the Prediction of Response to hCG Stimulation in Children With DSD

INTRODUCTION

The relationship between serum anti-Müllerian hormone (AMH) and the testosterone response to human chorionic gonadotropin (hCG) stimulation test is unclear.

METHODS

Children who had hCG stimulation tests in one tertiary centre from 2001 to 2018 were included (n = 138). Serum testosterone was measured before (day 1 [D1]) and after 3 days (D4) of hCG stimulation. Sixty-one of these children also had prolonged hCG stimulation for 2 more weeks and serum testosterone measured after 21 days (D22). All children had a serum AMH measured on D1.

RESULTS

Of the 138 children, D4 testosterone was normal in 104 (75%). AMH was low in 24/138 (17%) children, and 16 (67%) of these had a low D4 testosterone. Median AMH in those who had a normal vs low D4 testosterone was 850 pmol/L (24, 2280) and 54 pmol/L (0.4, 1664), respectively (P < 0.0001). An AMH > 5th centile was associated with a low D4 testosterone in 18/118 (13%; P < 0.0001). Of the 61 children who had prolonged hCG stimulation, D22 testosterone was normal in 39 (64%). AMH was low in 10/61(16%) children and 9 (90%) of these had a low D22 testosterone. Median AMH in children who responded and did not respond by D22 was 639 pmol/L (107, 2280) and 261 pmol/L (15, 1034) (P < 0.0001).

CONCLUSION

A normal AMH may provide valuable information on overall testicular function. However, a low AMH does not necessarily predict a suboptimal testosterone response to hCG stimulation.

Dynamic Testing for Evaluation of Adrenal and Gonadal Function in Pediatric and Adult Endocrinology: An Overview

Dynamic tests are often considered as the backbone of endocrinology. These tests involve the use of an exogenous agent to manipulate the body's hormonal milieu for the diagnosis and characterization of an endocrine disorder. They are especially helpful in the evaluation of certain endocrine conditions, such as disorders of growth and pubertal maturation and disorders of sex development. A great deal of heterogeneity exists across clinicians with regard to the usage, methodology, and interpretation of these tests. This review outlines various dynamic tests used to evaluate adrenal and gonadal function in pediatric and adult endocrinology, along with their clinical application and interpretation.

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.

Integrating clinical and genetic approaches in the diagnosis of 46,XY disorders of sex development

46,XY differences and/or disorders of sex development (DSD) are clinically and genetically heterogeneous conditions. Although complete androgen insensitivity syndrome has a strong genotype-phenotype correlation, the other types of 46,XY DSD are less well defined, and thus, the precise diagnosis is challenging. This study focused on comparing the relationship between clinical assessment and genetic findings in a cohort of well-phenotyped patients with 46,XY DSD. The study was an analysis of clinical investigations followed by genetic testing performed on 35 patients presenting to a single center. The clinical assessment included external masculinization score (EMS), endocrine profiling and radiological evaluation. Array-comparative genomic hybridization (array-CGH) and sequencing of DSD-related genes were performed. Using an integrated approach, reaching the definitive diagnosis was possible in 12 children. The correlation between clinical and genetic findings was higher in patients with a more severe phenotype (median EMS 2.5 vs 6; P = 0.04). However, in 13 children, at least one variant of uncertain significance was identified, and most times this variant did not correspond to the original clinical diagnosis. In three patients, the genetic studies guided further clinical assessment which resulted in a reclassification of initial clinical diagnosis. Furthermore, we identified eight patients harboring variants in more than one DSD genes, which was not seen in controls (2.5%; P = 0.0003). In summary, taking into account potential challenges in reaching the definitive diagnosis in 46,XY DSD, only integrated approach seems to be the best routine practice.

Prevalence of endocrine and genetic abnormalities in boys evaluated systematically for a disorder of sex development

STUDY QUESTION

What is the likelihood of identifying genetic or endocrine abnormalities in a group of boys with 46, XY who present to a specialist clinic with a suspected disorder of sex development (DSD)?

SUMMARY ANSWER

An endocrine abnormality of the gonadal axis may be present in a quarter of cases and copy number variants (CNVs) or single gene variants may be present in about half of the cases.

WHAT IS KNOWN ALREADY

Evaluation of 46, XY DSD requires a combination of endocrine and genetic tests but the prevalence of these abnormalities in a sufficiently large group of boys presenting to one specialist multidisciplinary service is unclear.

STUDY, DESIGN, SIZE, DURATION

This study was a retrospective review of investigations performed on 122 boys.

PARTICIPANTS/MATERIALS, SETTING, METHODS

All boys who attended the Glasgow DSD clinic, between 2010 and 2015 were included in the study. The median external masculinization score (EMS) of this group was 9 (range 1-11). Details of phenotype, endocrine and genetic investigations were obtained from case records.

MAIN RESULTS AND THE ROLE OF CHANCE

An endocrine abnormality of gonadal function was present in 28 (23%) with a median EMS of 8.3 (1-10.5) whilst the median EMS of boys with normal endocrine investigations was 9 (1.5-11) (P = 0.03). Endocrine abnormalities included a disorder of gonadal development in 19 (16%), LH deficiency in 5 (4%) and a disorder of androgen synthesis in 4 (3%) boys. Of 43 cases who had array-comparative genomic hybridization (array-CGH), CNVs were reported in 13 (30%) with a median EMS of 8.5 (1.5-11). Candidate gene analysis using a limited seven-gene panel in 64 boys identified variants in 9 (14%) with a median EMS of 8 (1-9). Of the 21 boys with a genetic abnormality, 11 (52%) had normal endocrine investigations.

LIMITATIONS, REASONS FOR CAUTION

A selection bias for performing array-CGH in cases with multiple congenital malformations may have led to a high yield of CNVs. It is also possible that the yield of single gene variants may have been higher than reported if the investigators had used a more extended gene panel.

WIDER IMPLICATIONS OF THE FINDINGS

The lack of a clear association between the extent of under-masculinization and presence of endocrine and genetic abnormalities suggests a role for parallel endocrine and genetic investigations in cases of suspected XY DSD.

STUDY FUNDING/COMPETING INTEREST(S)

RN was supported by the James Paterson Bursary and the Glasgow Children's Hospital Charity Summer Scholarship. SFA, RM and EST are supported by a Scottish Executive Health Department grant 74250/1 for the Scottish Genomes Partnership. EST is also supported by MRC/EPSRC Molecular Pathology Node and Wellcome Trust ISSF funding. There are no conflicts of interest.

TRIAL REGISTRATION NUMBER

None.

Pubertal Development in 17Beta-Hydroxysteroid Dehydrogenase Type 3 Deficiency

BACKGROUND

17β-hydroxysteroid dehydrogenase (17β-HSD) type 3 deficiency is an autosomal recessive disorder with diminished testosterone synthesis and consequently underandrogenisation. 46,XY patients with 17β-HSD type 3 deficiency are often assigned a female sex at birth but have a high virilisation potential at the time of puberty.

METHODS

We studied four 46,XY patients with 17β-HSD type 3 deficiency at puberty with regard to the underlying mutations, the hormone values, and the clinical findings.

RESULTS

Three patients were initially assigned a female sex and 1 was assigned a male sex. All had relevant mutations in the HSD17B3 gene. The 2 patients with deleterious mutations had lower testosterone values at the time of puberty than the patients with possible residual activity of 17β-HSD type 3. One of the latter patients changed to male gender.

CONCLUSION

All 4 patients with 17β-HSD type 3 deficiency synthesized relevant amounts (>0.7 µg/L) of testosterone at puberty, which lead to variable androgenisation. In patients with presumable residual activity of the mutated enzyme, testosterone values in the male reference range can be achieved, thereby inducing male pubertal development. These patients should possibly be assigned a male sex. Any surgical intervention should be avoided until the patients are old enough to consider their options of medical and surgical intervention.
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17β-Hydroxysteroid dehydrogenase 3 deficiency: Three case reports and a systematic review

17β-Hydroxysteroid dehydrogenase 3 deficiency is a rare autosomal recessive cause of 46, XY disorders of sex development resulting from HSD17B3 gene mutations, however, no case has been reported in East Asia. The aim of this study was to report three Chinese 46, XY females with 17β-HSD3 deficiency in a single center and perform a systematic review of the literature. Clinical examination, endocrine evaluation and HSD17B3 gene sequencing were performed in the three Chinese phenotypically females (two sisters and one unrelated patient). Relevant articles were searched by using the term "HSD17B3" OR "17beta-HSD3 gene" with restrictions on language (English) and species (human) in Pubmed and Embase. All the three phenotypically female subjects showed 46, XY karyotype, inguinal masses, decreased testosterone and increased androstenedione. Two novel homozygous mutations (W284X and c.124_127delTCTT) in HSD17B3 gene were identified. A systematic review found a total of 121 pedigrees/158 patients, with 78.5% (124/158) of patients assigned as females, 15.2% (24/158) from females to males, and 5.1% (8/158) raised as males. The most common mutation was c.277+4C>T (allele frequency: 25/72) for patients from Europe, and R80Q (allele frequency: 21/54) for patients from West Asia. The testicular histology showed normal infantile testicular tissue in 100% (9/9) infantile patients, normal quantity germ cells in 44.4% (8/18) prepubertal patients and 19.0% (4/21) pubertal and adult patients. We reported the first East Asian 17β-hydroxysteroid dehydrogenase 3 deficiency cases. Additional literature reviews found founder effects among patients with different ethnic background and early orchiopexy may benefit fertility in patients assigned as males. These findings may significantly expand the clinical, ethnic and genetic spectrum of 17β-hydroxysteroid dehydrogenase 3 deficiency.

Novel mutations of HSD17B3 in three Chinese patients with 46,XY Disorders of Sex Development

17β-Hydroxysteroid dehydrogenase type 3 (17β-HSD3) converts the inactive Δ4-androstenedione (A) to testosterone (T). Its deficiency is the most common testosterone biosynthesis defect that results in 46,XY Disorders Of Sex Development (DSD). However, the disease is difficult to distinguish from other 46,XY DSD for similar clinical phenotypes. Therefore, genetic testing provides good criteria for the diagnosis of the disease. In this study, HSD17B3 gene was examined in 3 unrelated Chinese patients with 46,XY DSD. Direct sequencing and quantitative PCR of HSD17B3 gene revealed the presence of a compound heterozygous mutation (p.I60T/exon1 deletion) in Patient 1, a homozygous (p.I60T) mutation in Patient 2 and a frameshift mutation (p.V25Efs∗54) and an exon1 deletion in Patient 3. All of the mutations have not been reported previously. These novel mutations may expand the mutation database of HSD17B3 gene and provide us new insights into the molecular mechanism of 17β-HSD3 deficiency. It is noteworthy that when direct sequence analysis showed a rare homozygous mutation in patients with non-consanguineous parents, "apparent homozygosity" should be taken into an account and the intragenic deletion should be screened. In addition, when single mutation was found in patients with disease in recessive heredity mode, the intragenic deletion should also be screened.

Novel cases of Tunisian patients with mutations in the gene encoding 17β-hydroxysteroid dehydrogenase type 3 and a founder effect

17β-Hydroxysteroid dehydrogenase type 3 (17β-HSD3) is expressed almost exclusively in the testis and converts Δ4-androstene-3,17-dione to testosterone. Mutations in the HSD17B3 gene causing 17β-HSD3 deficiency are responsible for a rare recessive form of 46, XY Disorders of Sex Development (46, XY DSD). We report novel cases of Tunisian patients with 17β-HSD3 deficiency due to previously reported mutations, i.e. p.C206X and p.G133R, as well as a case with the novel compound heterozygous mutations p.C206X and p.Q176P. Moreover, the previously reported polymorphism p.G289S was identified in a heterozygous state in combination with a novel non-coding variant c.54G>T, also in a heterozygous state, in a male patient presenting with micropenis and low testosterone levels. The identification of four different mutations in a cohort of eight patients confirms the generally observed genetic heterogeneity of 17β-HSD3 deficiency. Nevertheless, analysis of DNA from 272 randomly selected healthy controls from the same geographic area (region of Sfax) revealed a high carrier frequency for the p.C206X mutation of approximately 1 in 40. Genotype reconstruction of the affected pedigree members revealed that all p.C206X mutation carriers harbored the same haplotype, indicating inheritance of the mutation from a common ancestor. Thus, the identification of a founder effect and the elevated carrier frequency of the p.C206X mutation emphasize the importance to consider this mutation in the diagnosis and genetic counseling of affected 17β-HSD3 deficiency pedigrees in Tunisia.

46,XY disorder of sex development (DSD) due to 17β-hydroxysteroid dehydrogenase type 3 deficiency

17β-hydroxysteroid dehydrogenase 3 deficiency consists of a defect in the last phase of steroidogenesis, in which androstenedione is converted into testosterone and estrone into estradiol. External genitalia range from female-like to atypical genitalia and most affected males are raised as females. Virilization in subjects with 17β-HSD3 deficiency occurs at the time of puberty and several of them change to male social sex. In male social sex patients, testes can be safely maintained, as long as they are positioned inside the scrotum The phenotype of 46,XY DSD due to 17β-HSD3 deficiency is extremely variable and clinically indistinguishable from other causes of 46,XY DSD such as partial androgen insensitivity syndrome and 5α-reductase 2 deficiency. Laboratory diagnosis is based on a low testosterone/androstenedione ratio due to high serum levels of androstenedione and low levels of testosterone. The disorder is caused by a homozygous or compound heterozygous mutations in the HSD17B3 gene that encodes the 17β-HSD3 isoenzyme leading to an impairment of the conversion of 17-keto into 17-hydroxysteroids. Molecular genetic testing confirms the diagnosis and provides the orientation for genetic counseling. Our proposal in this article is to review the previously reported cases of 17β-HSD3 deficiency adding our own cases.

Retracted: Aetiology and clinical profile of children with 46, XY differences of sex development at an Indian referral centre

Retraction: 'Aetiology and clinical profile of children with 46, XY differences of sex development at an Indian referral centre' by Vasundhera Chauhan, Rima Dada, Vandana Jain The above article, published online on 8 August 2016 in Wiley Online Library (http://wileyonlinelibrary.com), has been retracted by agreement between the authors, the Journal Editors-in-Chief, Wolf-Bernhard Schill and Ralf Henkel, and Blackwell Verlag GmbH. The retraction has been agreed as the result of an unresolved dispute between the first author and a colleague research fellow due to the inclusion of data from patients who were simultaneously enrolled in two studies being conducted separately by the two parties. Reference Chauhan, V., Dada, R. and Jain, V. (2016), Aetiology and clinical profile of children with 46, XY differences of sex development at an Indian referral centre. Andrologia. doi:10.1111/and.12663.

46,XY disorder of sex development due to 17-beta hydroxysteroid dehydrogenase type 3 deficiency: a plea for timely genetic testing

BACKGROUND

17β-hydroxysteroid dehydrogenase type 3 (17βHSD3) deficiency is a rare cause of disorder of sex development (DSD) due to impaired conversion of androstenedione to testosterone. Traditionally, the diagnosis was determined by βHCG-stimulated ratios of testosterone:androstenedione < 0.8.

CASE PRESENTATION

An otherwise phenotypically female infant presented with bilateral inguinal masses and a 46,XY karyotype. βHCG stimulation (1500 IU IM for 2 days) suggested 17βHSD3 deficiency although androstenedione was only minimally stimulated (4.5 nmol/L to 5.4 nmol/L). Expedient genetic testing for the HSD17B3 gene provided the unequivocal diagnosis.

CONCLUSION

We advocate for urgent genetic testing in rare causes of DSD as indeterminate hormone results can delay diagnosis and prolong intervention.

Clinical, hormonal and radiological profile of 46XY disorders of sexual development

BACKGROUND AND OBJECTIVES

46 XY disorders of sexual development (DSD) cover a wide spectrum of phenotypes ranging from unambiguous female genitalia to ambiguous male genitalia with hypospadias or dysgenetic gonads. Management of these patients depends on the cause of DSD, degree of feminization, age at presentation, and gender orientation. The aim of this study was to evaluate the presentation and management of patients with 46XY DSD at our center.

PATIENTS AND METHODS

All new and old patients of 46XY DSD attending the endocrine OPD in a period of 16 months were included in this study. Clinical, cytogenetic, hormonal, and radiological evaluation were done to identify the cause of DSD.

RESULTS

Among 19 patients, eight were diagnosed with disorders of gonadal development (one with complete gonadal dysgenesis, four with partial gonadal dysgenesis, two with congenital bilateral anorchia, and one with ovotesticular DSD) and eight with disorders of androgen synthesis and action (one with complete androgen insensitivity syndrome [AIS], three with partial AIS and four with 5α reductase deficiency). In three patients, a definitive diagnosis could not be made.

CONCLUSIONS

Management of patients with DSD depends on etiology, gender assignment, gender orientation, hormonal treatment, genital surgery, and consequent psychosocial implications. Due to the overlapping clinical and biochemical parameters in different subsets of DSD, only a preliminary etiological diagnosis can be made in some cases. Genetic studies with long-term follow-up are required for an accurate diagnosis.

Severe Undervirilisation in a 46,XY Case Due to a Novel Mutation in HSD17B3 Gene

17-β-hydroxysteroid dehydrogenase type 3 (17β-HSD3) is an important enzyme involved in the final steps of androgen synthesis and is required for the development of normal male external genitalia. 46,XY individuals with deficiency of this enzyme present a wide clinical spectrum from a female appearance of the external genitalia through ambiguous genitalia to a predominantly male genitalia with micropenis or hypospadias. This paper reports a one-year-old 46,XY patient with 17β-HSD3 deficiency who presented with female external genitalia and bilaterally palpable gonads in the inguinal region. The low T/Δ4 ratio after human chorionic gonadotropin (hCG) stimulation suggested 17β-HSD3 deficiency. A homozygous mutation, c.761_762delAG, was determined at the intron 9/exon 10 splice site of the HSD17B3 gene. To the best of our knowledge, this mutation has not been reported thus far, but its localization and type would imply a complete disruption of the 17β-HSD3 which may explain the phenotype of our patient.

Screening for mutations in 17β-hydroxysteroid dehydrogenase and androgen receptor in women presenting with partially virilised 46,XY disorders of sex development

CONTEXT AND OBJECTIVE

The precise diagnosis of partially virilised women with 46,XY disorders of sex development (DSD) is often obscure. In practice, this group often comes under the poorly defined, clinically based label of partial androgen insensitivity syndrome (PAIS). In a previous study, we found that 5α-reductase 2 (SRD5A2) mutations occurred in 43% of women in this subgroup. We expand this work to include biochemical and genetic screening for 17β-hydroxysteroid dehydrogenase (HSD17B3) and androgen receptor (AR) mutations.

METHODS

Analysis of serum androgens (androstenedione and testosterone) and genetic analyses for HSD17B3 and AR were performed in 42 women from 36 pedigrees with partially virilised 46,XY DSD in whom SRD5A2 deficiency had been excluded by urine steroid profiling.

RESULTS

Out of 36 unrelated women, 14 (38%) were found to have HSD17B3 mutations and one (2.7%) to have an AR defect. Six novel pathogenic HSD17B3 mutations were identified: three splice site mutations and three missense changes. Seven patients with HSD17B3 deficiency tested before gonadectomy had basal testosterone/androstenedione (T/A) ratio <0.8 (sensitivity 100% and specificity 91%).

CONCLUSIONS

HSD17B3 deficiency is prevalent in the adolescent and adult 46,XY female DSD population and is often associated with lesser degrees of virilisation compared with those with 5α-reductase deficiency. This diagnosis should be considered for individuals labelled as PAIS, particularly, but not exclusively, those who present with virilisation at puberty or primary amenorrhoea. Before gondadectomy, T/A ratio is useful to aid diagnosis, but after gonadectomy sequencing of HSD17B3 must be performed to confirm the diagnosis.

46,XY disorder of sex development in a sudanese patient caused by a novel mutation in the HSD17B3 gene

In this study, we present a Sudanese 46,XY patient raised as a female and diagnosed at the age of 20 years with having 17β-hydroxysteroid dehydrogenase type 3 (17β-HSD3) deficiency. She presented with primary amenorrhea, undeveloped breasts and a male pattern of secondary sexual characteristics. Examination of her external genitalia showed type IV genital circumcision. Steroid measurements both in urine and serum pointed to 17β-HSD3 deficiency. A novel homozygous splice-site mutation [c.524 + 2T>A] was detected in intron 7 of the HSD17B3 gene. In this patient, steroid concentration clearly supported both the clinical diagnosis of 17β-HSD3 deficiency and the functional relevance of the mutation. Interestingly, despite of the type IV genital circumcision, the patient expressed her interest in reassigning her sex from female to male.

Steroidogenesis of the testis -- new genes and pathways

Defects of androgen biosynthesis cause 46,XY disorder of sexual development (DSD). All steroids are produced from cholesterol and the early steps of steroidogenesis are common to mineralocorticoid, glucocorticoid and sex steroid production. Genetic mutations in enzymes and proteins supporting the early biosynthesis pathways cause adrenal insufficiency (AI), DSD and gonadal insufficiency. The classic androgen biosynthesis defects with AI are lipoid CAH, CYP11A1 and HSD3B2 deficiencies. Deficiency of CYP17A1 rarely causes AI, and HSD17B3 or SRD5A2 deficiencies only cause 46,XY DSD and gonadal insufficiency. All androgen biosynthesis depends on 17,20 lyase activity of CYP17A1 which is supported by P450 oxidoreductase (POR) and cytochrome b5 (CYB5). Therefore 46,XY DSD with apparent 17,20 lyase deficiency may be due to mutations in CYP17A1, POR or CYB5. Illustrated by patients harboring mutations in SRD5A2, normal development of the male external genitalia depends largely on dihydrotestosterone (DHT) which is converted from circulating testicular testosterone (T) through SRD5A2 in the genital skin. In the classic androgen biosynthetic pathway, T is produced from DHEA and androstenedione/-diol in the testis. However, recently found mutations in AKR1C2/4 genes in undervirilized 46,XY individuals have established a role for a novel, alternative, backdoor pathway for fetal testicular DHT synthesis. In this pathway, which has been first elucidated for the tammar wallaby pouch young, 17-hydroxyprogesterone is converted directly to DHT by 5α-3α reductive steps without going through the androgens of the classic pathway. Enzymes AKR1C2/4 catalyse the critical 3αHSD reductive reaction which feeds 17OH-DHP into the backdoor pathway. In conclusion, androgen production in the fetal testis seems to utilize two pathways but their exact interplay remains to be elucidated.

Understanding the genetic aetiology in patients with XY DSD

BACKGROUND

Disorders of sex development (DSD) consist of a wide range of disorders and are commoner in those with an XY karyotype. In over half of these cases who have a 46,XY karyotype and who are raised as boys, the underlying aetiology remains unclear.

AREAS OF AGREEMENT

Identification of the underlying genetic abnormality may predict long-term outcome. However, genetic abnormalities that are associated with XY DSD manifest themselves with a wide range of phenotype. To understand the aetiology as well as the phenotypic variation, there is a need to harness the advanced genetic technology that is now available.

AREAS OF CONTROVERSY

The point at which genetic analysis should be undertaken in the course of investigations is unclear. In addition, there is little agreement on the most effective approach for genetic analysis that will be of clinical benefit to the patient.

AREAS TIMELY FOR DEVELOPING RESEARCH

There is a need to understand and improve the clinical utility of genetic analysis in the clinical setting of the patient with a suspected DSD. This will be even more important when parallel gene sequencing identifies variations in multiple genes.

Clinical and molecular spectrum of patients with 17β-hydroxysteroid dehydrogenase type 3 (17-β-HSD3) deficiency

The enzyme 17β-hydroxysteroid dehydrogenase type 3 (17-β-HSD3) catalyzes the conversion of androstenedione to testosterone in the testes, and its deficiency is a rare disorder of sex development in 46,XY individuals. It can lead to a wide range of phenotypic features, with variable hormonal profiles. We report four patients with the 46,XY karyotype and 17-β-HSD3 deficiency, showing different degrees of genital ambiguity, increased androstenedione and decreased testosterone levels, and testosterone to androstenedione ratio < 0.8. In three of the patients, diagnosis was only determined due to the presence of signs of virilization at puberty. All patients had been raised as females, and female gender identity was maintained in all of them. Compound heterozygosis for c.277+2T>G novel mutation, and c.277+4A>T mutation, both located within the intron 3 splice donor site of the HSD17B3 gene, were identified in case 3. In addition, homozygosis for the missense p.Ala203Val, p.Gly289Ser, p.Arg80Gln mutations were found upon HSD17B3 gene sequencing in cases 1, 2, and 4, respectively. Arq Bras Endocrinol Metab. 2012;56(8):533-9

Isolated mild clitoral hypertrophy may reveal 46,XY disorders of sex development in infancy due to 17βHSD-3 defect confirmed by molecular analysis

AIMS

17-β-Hydroxysteroid dehydrogenase type 3 (17βHSD-3) is expressed exclusively in the testes where it converts Δ4 androstenedione (Δ4) to testosterone (T). Here, we report a patient with a rare mutation at a critical site in HSD17B3 gene leading to deficiency of 17β HSD-3 enzyme.

METHODS

We describe a 3-year old healthy female of consanguineous Lebanese descent, who presented to the endocrine service with isolated mild clitoromegaly. Adrenocorticotropic hormone (ACTH) and human chorionic gonadotrophin (hCG) stimulation tests were performed. Genes for sex-determining region Y (SRY), steroidogenic factor-1 (SF-1) and 17βHSD-3 (HSD17B3) were sequenced.

RESULTS

The post-hCG stimulation T levels and T/Δ4 ratio was low. Patient had a 46,XY karyotype. Sequence analysis of the HSD17B3 gene revealed a homozygous R80W missense mutation on exon 3. No mutation was found in SRY and SF1 genes. Mullerian structures were not detected on pelvic imaging.

CONCLUSIONS

A low T/Δ4 ratio is indicative of 17βHSD-3 deficiency and associated with isolated clitoromegaly. The R80 site is critical for NADPH binding, thus the mutation at this site leads to 17βHSD-3 deficiency presenting as 46,XY disorder of sex development.

The XY female

Sexual differentiation depends upon a series of complex events that leads to the differentiation of gonads into testicular tissue and the production and action of androgens on genital tissue. Variations in any of the pathways affecting the above events can lead into conditions where the phenotype and genotype are discordant, conditions nowadays called disorders of sex development (DSDs). These conditions may have some aspects in common such as infertility and the need for feminising surgery or gonadectomy. However, each entity has its particularities, and it is necessary that every effort is made to reach the correct diagnosis. As genetic information becomes more readily available, these conditions can be diagnosed with more ease and appropriate counselling can be provided to other members of the family regarding the treatment options and risk. Due to the rarity of DSDs, it is important that their management is undertaken in tertiary referral centres with accumulated experience on diagnosis and management and where a multidisciplinary team can provide the necessary medical and surgical support. Disclosure of the diagnosis should be done in a sensitive way by experienced staff, and psychological counselling should be readily available to patients and their family.

Immunohistochemical localization of fibrillin-1 protein in the cells of chick corneal and conjunctival epithelia during pre- and postnatal development

Fibrillin-1 protein is a microfibrillar glycoprotein component of the extracellular matrix, widely distributed in ocular connective tissues. In this work, we show for the first time the expression pattern of fibrillin-1 protein in the corneal and conjunctival epithelia and in stromal keratocytes during embryo development. After hatching, protein expression was maintained in the corneal epithelium cells and nonsecreting epithelium cells of the conjunctiva and disappeared in the stromal keratocytes. In the limbus region, the basal cells were negative, while superficial cells were positive for the antibody. The expression in corneal epithelial cells suggests a role for fibrillin in development and disease. Therefore, some basal cells of the limbus region do not show fibrillin-1 immunolocalization, and this may be correlated with stem cell or stem-like properties.

Prolonged human chorionic gonadotrophin stimulation as a tool for investigating and managing undescended testes

OBJECTIVE

To observe the outcome in a group of children with undescended testes (UDT) given prolonged human chorionic gonadotrophin (hCG) stimulation as part of their management.

STUDY DESIGN

Retrospective review of 16 prepubertal boys given intramuscular hCG, 1500 U, on Days 1, 2 and 3 and then twice a week for 2 weeks with assessment of serum testosterone (T), SHBG, dihydrotestosterone (DHT) and androstenedione (A) on Days 1, 4 and 22.

RESULTS

In seven boys (44%), peak rise in T was by Day 4; in 5 boys (31%), the rise was by Day 22 and in the remainder, serum T stayed low. The median Day1 testosterone : androstenedione (T : A) ratio rose from 0.4 (range 0.2-1.5) to 1.7 (range 0.2-5.3) at Day 4 (P < 0.05) with no further rise by Day 22. The median dihydrotestosterone : testosterone ratio (DHT : T) at Day 1 and Day 4 remained unchanged. SHBG levels were more likely to be lower at Day 22 than at Day 4. The mean testosterone : SHBG (T : SHBG) ratio as a marker of androgen sensitivity was 0.2 (1SD 0.1). Bilateral testicular descent deemed immediate surgery unnecessary in 3 out of 15 (20%) boys where outcome data were available.

CONCLUSION

Whilst a 3-day hCG stimulation regimen may exclude 17beta-hydroxysteroid dehydrogenase-3 and 5alpha-reductase deficiencies, some boys with cryptorchidism may require more prolonged stimulation to assess androgen production and sensitivity. The possibility that this regimen leads to a reduced need for orchidopexy requires further exploration.

Phenotypic variability in 17beta-hydroxysteroid dehydrogenase-3 deficiency and diagnostic pitfalls

OBJECTIVE

17beta-hydroxysteroid dehydrogenase type 3 isoenzyme (17beta-HSD3) is required to produce testosterone for male sex differentiation. Mutations in the HSD17B3 gene cause 17betaHSD3 deficiency and result in XY sex reversal of varying degree. We report the phenotypes of 14 subjects with 17betaHSD3 deficiency in relation to sex of rearing, androgen production, and HSD17B3 mutations.

DESIGN

Cases were identified through the Cambridge Disorders of Sex Development Database where detailed clinical information was recorded, results of hCG stimulation tests were available, and HSD17B3 mutation was identified.

RESULTS

Fourteen subjects from seven pedigrees (four consanguineous) had the following seven mutations: A56T, N130S, E215D, S232L, C268Y, V205E, and a novel mutation M197K. XY sex reversal was classified as complete in 10 infants at birth. Inguinal masses suggestive of androgen insensitivity syndrome (AIS) occurred in five infants. Contrasexual virilization reminiscent of 5alpha-reductase deficiency occurred in four subjects at puberty. The median (range) testosterone : androstenedione (T/A) ratio after a short hCG stimulation test was 0.32 (0.12-3.4). The S232L mutation identified in three affected family members caused isolated, severe hypospadias in one member who was raised male; virilization occurred despite in vitro studies showing an inactive mutant enzyme. Ratios of T/A in this pedigree were more than 0.8.

CONCLUSION

XY sex reversal is sufficiently variable in 17betaHSD3 deficiency to cause problems in accurate diagnosis, particularly in distinguishing it from AIS. It should be considered in undervirilized male infants with normal Wolffian duct structures, absent Müllerian ducts, and normal adrenal steroid biosynthesis; or when an assigned female subject virilizes at puberty. Elevated hCG-stimulated T/A ratio may occur, and sex of rearing may not be concordant within affected families with the same HSD17B3 mutation. The T/A ratio, mutation analysis and functional analysis of the mutant enzyme taken in isolation, respectively, may not conclusively establish a diagnosis of 17betaHSD3 deficiency in undervirilized male subjects; the reasons for these discrepancies remain unknown.

17beta-hydroxysteroid dehydrogenase-3 deficiency: a rare endocrine cause of male-to-female sex reversal

Deficiency of 17beta-hydroxysteroid dehydrogenase type 3 (17beta-HSD3), due to mutations in the gene encoding the enzyme, results in a rare autosomal recessive form of male-to-female sex reversal. Mutated genes encode an abnormal enzyme with absent or reduced ability to convert Delta4-androstenedione to testosterone in the testis. Affected individuals are genetically males who developed internal male Wolffian structures but female external genitalia. Such individuals are usually raised as females and diagnosis is made at puberty, when they show virilization. Correct diagnosis is mandatory to optimize treatment and follow-up. In the present paper we report the clinical history, endocrine evaluation and molecular genetics of a prepubertal girl affected by 17beta-HSD3 deficiency, in whom an erroneous diagnosis of androgen insensitivity syndrome was made. The clinical, endocrine and genetic features of 17beta-HSD3 deficiency are also reviewed.

Practical management of the intersex infant

Intersex occurs when the appearance of the internal or external genitalia is at variance with normal development for either sex. The first question asked by, and of new parents in relation to their offspring is often "Is it a boy or a girl"? A rational approach, based on knowledge of normal prenatal sexual development, and based on a careful physical examination to guide further investigation, is required to reach a diagnosis. We briefly review prenatal sexual development to provide a background to the assessment of genital ambiguity in the newborn. Aspects of physical examination are discussed in detail, with reference to published normative data where possible. We provide a classification of genital ambiguity and an approach to differential diagnosis. We highlight some of the many syndromes associated with genital ambiguity, with reference to their genetic basis where possible. In 46,XX individuals, the commonest cause of genital ambiguity is congenital adrenal hyperplasia due to 21-hydroxylase deficiency; however, in 46,XY individuals the differential diagnosis is wide, and may remain unexplained, even after extensive investigation. Two algorithms are presented, one of which provides an initial approach based on the presence of a uterus and palpable gonads alone, and a second illustrating a comprehensive differential diagnosis of the undervirilised 46,XY individual. We discuss our approach to sharing information on the diagnosis and management with the parents and highlight the early involvement of an experienced multidisciplinary team. Finally, we consider current controversial issues relating to gender assignment and management of genital ambiguity.

The genetics of male undermasculinization

A review of the genetics of male undermasculinization must encompass a description of the embryology of the genital system. The dimorphism of sex development consequent upon the formation of a testis and the subsequent secretion of hormones to impose a male phenotype is highlighted. Thus, an understanding of the causes of male undermasculinization (manifest as XY sex reversal, complete and partial) includes reviewing the genetic factors which control testis determination and the production and action of testicular hormones. The study of disorders of male sex development has contributed substantially to knowledge of normal male development before birth. This knowledge has been complimented in recent years by the use of targeted murine gene disruption experiments to study the sex phenotype, although murine and human phenotypes are not always concordant. The investigation of disorders associated with male undermasculinization of prenatal onset is described briefly to complete the review.