Idiopathic gonadotrophin deficiency: genetic questions addressed through phenotypic characterization

Clinical phenotype of a Kallmann syndrome patient with IL17RD and CPEB4 variants

Background

This study aimed to characterize the clinical phenotype and genetic variations in patients with Kallmann syndrome (KS).

Methods

This study involved the collection and analysis of clinical data from an individual with sporadic KS. Following this, peripheral blood samples were obtained from the patient and his parents. Genomic deoxyribonucleic acid was extracted and subjected to whole-exome sequencing and genomic copy number variation (CNV) detection. Finally, Sanger sequencing was performed to validate the suspected pathogenic variants.

Results

Whole-exome sequencing confirmed that the child carried both the IL17RD variant (c.2101G>A, p.Gly701Ser) inherited from the mother and the new CPEB4 variant (c.1414C>T, p.Arg472*). No pathogenic CNVs were identified in CNV testing.

Conclusion

Bioinformatics analysis shows that the IL17RD protein undergoing Gly701Ser mutation and is speculated to be phosphorylated and modified, thereby disrupting fibroblast growth factor signaling. This study also suggested that the CPEB4 might play a crucial role in the key signaling process affecting olfactory bulb morphogenesis. Overall, the findings of this study broaden the gene expression profile of KS-related pathogenic genes. This offers a new avenue for exploring the pathogenic mechanism of KS and provides valuable insights for precise clinical diagnosis and treatment strategies for this condition.

Gonadal Function in Boys with Bilateral Undescended Testes

Background

Bilateral undescended testes (BUDT) may be a marker of an underlying condition that affects sex development or maturation.

Aims

To describe the extent of gonadal dysfunction in cases of BUDT who had systematic endocrine and genetic evaluation at a single tertiary pediatric center.

Methods

A retrospective review was conducted of all boys with BUDT who had endocrine evaluation between 2008 and 2021 at the Royal Hospital for Children, Glasgow (RHCG). Continuous variables were analyzed using Mann-Whitney U and non-continuous variables using Fisher's exact, via Graphpad Prism v 8.0. Multivariable logistic regression was used to identify any associations between groups. A P < .05 was considered statistically significant.

Results

A total of 243 bilateral orchidopexies were performed at RHCG between 2008 and 2021. Of these 130 (53%) boys were seen by the endocrine team. The median (range) age at first orchidopexy was 1 year (0.2, 18.0) with 16 (12%) requiring re-do orchidopexy. The median External Masculinization Score of the group was 10 (2, 11) with 33 (25%) having additional genital features. Of the 130 boys, 71 (55%) had extragenital anomalies. Of the 70 who were tested, a genetic abnormality was detected in 38 (54%), most commonly a chromosomal variant in 16 (40%). Of the 100 who were tested, endocrine dysfunction was identified in 38 (38%).

Conclusion

Genetic findings and evidence of gonadal dysfunction are common in boys who are investigated secondary to presentation with BUDT. Endocrine and genetic evaluation should be part of routine clinical management of all cases of BUDT.

Management of congenital hypogonadotropic hypogonadism in females

This review explores the challenges in the diagnosis of hypogonadotropic hypogonadism, the transition of care from paediatric to adult care and the considerable health implications of this condition. The role gynaecologists and general practitioners have in managing hormone replacement therapy and reproductive potential is also highlighted. The fertility treatment options, which include ovulation induction with gonadotrophins and in-vitro fertilisation, are discussed in detail along with highlighting the fact that anovulation and markers of low ovarian reserve prior to priming treatment may not be reflective of poor reproductive potential. The holistic management of women with hypogonadotropic hypogonadism is still not standardised and evidence for subfertility management is scarce. This review aims to highlight this concern and provide guidance by evaluating current evidence.

Mutation spectrum of Kallmann syndrome: identification of five novel mutations across ANOS1 and FGFR1

BACKGROUND

Kallmann syndrome (KS) is a common type of idiopathic hypogonadotropic hypogonadism. To date, more than 30 genes including ANOS1 and FGFR1 have been identified in different genetic models of KS without affirmatory genotype-phenotype correlation, and novel mutations have been found.

METHODS

A total of 35 unrelated patients with clinical features of disorder of sex development were recruited. Custom-panel sequencing or whole-exome sequencing was performed to detect the pathogenic mutations. Sanger sequencing was performed to verify single-nucleotide variants. Copy number variation-sequencing (CNV-seq) was performed to determine CNVs. The pathogenicity of the identified variant was predicted in silico. mRNA transcript analysis and minigene reporter assay were performed to test the effect of the mutation on splicing.

RESULTS

ANOS1 gene c.709 T > A and c.711 G > T were evaluated as pathogenic by several commonly used software, and c.1063-2 A > T was verified by transcriptional splicing assay. The c.1063-2 A > T mutation activated a cryptic splice acceptor site downstream of the original splice acceptor site and resulted in an aberrant splicing of the 24-basepair at the 5' end of exon 8, yielding a new transcript with c.1063-1086 deletion. FRFR1 gene c.1835delA was assessed as pathogenic according to the ACMG guideline. The CNV of del(8)(p12p11.22)chr8:g.36140000_38460000del was judged as pathogenic according to the ACMG & ClinGen technical standards.

CONCLUSIONS

Herein, we identified three novel ANOS1 mutations and two novel FGFR1 variations in Chinese KS families. In silico prediction and functional experiment evaluated the pathogenesis of ANOS1 mutations. FRFR1 c.1835delA mutation and del(8)(p12p11.22)chr8:g.36140000_38460000del were assessed as pathogenic variations. Therefore, our study expands the spectrum of mutations associated with KS and provides diagnostic evidence for patients who carry the same mutation in the future.

Genetic architecture of self-limited delayed puberty and congenital hypogonadotropic hypogonadism

Distinguishing between self limited delayed puberty (SLDP) and congenital hypogonadotropic hypogonadism (CHH) may be tricky as they share clinical and biochemical characteristics. and appear to lie within the same clinical spectrum. However, one is classically transient (SDLP) while the second is typically a lifetime condition (CHH). The natural history and long-term outcomes of these two conditions differ significantly and thus command distinctive approaches and management. Because the first presentation of SDLP and CHH is very similar (delayed puberty with low LH and FSH and low sex hormones), the scientific community is scrambling to identify diagnostic tests that can allow a correct differential diagnosis among these two conditions, without having to rely on the presence or absence of phenotypic red flags for CHH that clinicians anyway seem to find hard to process. Despite the heterogeneity of genetic defects so far reported in DP, genetic analysis through next-generation sequencing technology (NGS) had the potential to contribute to the differential diagnostic process between SLDP and CHH. In this review we will provide an up-to-date overview of the genetic architecture of these two conditions and debate the benefits and the bias of performing genetic analysis seeking to effectively differentiate between these two conditions.

Isolated anterior pituitary dysfunction in adulthood

Hypopituitarism is defined as a complete or partial deficiency in one or more pituitary hormones. Anterior hypopituitarism includes secondary adrenal insufficiency, central hypothyroidism, hypogonadotropic hypogonadism, growth hormone deficiency and prolactin deficiency. Patients with hypopituitarism suffer from an increased disability and sick days, resulting in lower health status, higher cost of care and an increased mortality. In particular during adulthood, isolated pituitary deficits are not an uncommon finding; their clinical picture is represented by vague symptoms and unclear signs, which can be difficult to properly diagnose. This often becomes a challenge for the physician. Aim of this narrative review is to analyse, for each anterior pituitary deficit, the main related etiologies, the characteristic signs and symptoms, how to properly diagnose them (suggesting an easy and reproducible step-based approach), and eventually the treatment. In adulthood, the vast majority of isolated pituitary deficits are due to pituitary tumours, head trauma, pituitary surgery and brain radiotherapy. Immune-related dysfunctions represent a growing cause of isolated pituitary deficiencies, above all secondary to use of oncological drugs such as immune checkpoint inhibitors. The diagnosis of isolated pituitary deficiencies should be based on baseline hormonal assessments and/or dynamic tests. Establishing a proper diagnosis can be quite challenging: in fact, even if the diagnostic methods are becoming increasingly refined, a considerable proportion of isolated pituitary deficits still remains without a certain cause. While isolated ACTH and TSH deficiencies always require a prompt replacement treatment, gonadal replacement therapy requires a benefit-risk evaluation based on the presence of comorbidities, age and gender of the patient; finally, the need of growth hormone replacement therapies is still a matter of debate. On the other side, prolactin replacement therapy is still not available. In conclusion, our purpose is to offer a broad evaluation from causes to therapies of isolated anterior pituitary deficits in adulthood. This review will also include the evaluation of uncommon symptoms and main etiologies, the elements of suspicion of a genetic cause and protocols for diagnosis, follow-up and treatment.

Unilaterally disrupted structural and functional connectivity of the fronto-limbic system in idiopathic hypogonadotropic hypogonadism

OBJECTIVE

Idiopathic hypogonadotropic hypogonadism (IHH) is rare and can either be associated with normal or defective olfactory sensation, classified as normosmic IHH (nIHH) or Kallmann syndrome (KS). We do not yet understand the central processing pathways in the olfactory system. We aimed to compare the resting-state structural and functional connectivity (FC) of olfactory neural pathways in patients with IHH. We hypotheses that alterations of structural connectivity and FC may exist in the olfactory cortex pathways in IHH patients.

DESIGN

STRUCTURAL AND FUNCTIONAL CONNECTIVITY DATA RESULTS BETWEEN TWO GROUPS WERE ANALYZED: Patients: Twenty-five IHH patients (13 nIHH patients and 12 KS patients) were recruited from the Department of Endocrinology and were assessed. A total of 25 age-matched healthy male controls were recruited from the community.

MEASUREMENTS

All subjects underwent diffusion tensor imaging and functional magnetic resonance imaging (fMRI) scans. Structural and functional connectivity data analyses were then performed. Pearson's correlation analyses were performed to investigate the correlations between the fractional anisotropy (FA) value and FC strength, showing significant differences among the three groups separately.

RESULTS

Compared with the HC group, FA value in the right uncinate fasciculus (UF) decreased significantly in the IHH group. The olfactory cortex FC values of the right gyrus rectus, orbitofrontal cortex (OFC) and right middle temporal gyrus in the IHH group were decreased compared with those in the HC group. Moreover, there were significant negative correlations between right UF FA and olfactory cortex-FC to both the gyrus rectus and OFC within the HC group (p &lt; .05).

CONCLUSION

Our findings suggest that alterations of structural and FC support the presence of neurobiological disruptions in IHH patients, particularly a specific structural-functional asymmetry disruption may exist in the olfactory cortex pathways in IHH patients.

New and Consolidated Therapeutic Options for Pubertal Induction in Hypogonadism: In-depth Review of the Literature

Delayed puberty (DP) defines a retardation of onset/progression of sexual maturation beyond the expected age from either a lack/delay of the hypothalamo-pituitary-gonadal axis activation or a gonadal failure. DP usually gives rise to concern and uncertainty in patients and their families, potentially affecting their immediate psychosocial well-being and also creating longer term psychosexual sequelae. The most frequent form of DP in younger teenagers is self-limiting and may not need any intervention. Conversely, DP from hypogonadism requires prompt and specific treatment that we summarize in this review. Hormone therapy primarily targets genital maturation, development of secondary sexual characteristics, and the achievement of target height in line with genetic potential, but other key standards of care include body composition and bone mass. Finally, pubertal induction should promote psychosexual development and mitigate both short- and long-term impairments comprising low self-esteem, social withdrawal, depression, and psychosexual difficulties. Different therapeutic options for pubertal induction have been described for both males and females, but we lack the necessary larger randomized trials to define the best approaches for both sexes. We provide an in-depth and updated literature review regarding therapeutic options for inducing puberty in males and females, particularly focusing on recent therapeutic refinements that better encompass the heterogeneity of this population, and underlining key differences in therapeutic timing and goals. We also highlight persistent shortcomings in clinical practice, wherein strategies directed at "the child with delayed puberty of uncertain etiology" risk being misapplied to older adolescents likely to have permanent hypogonadism.

Genetic and phenotypic differences between sexes in congenital hypogonadotropic hypogonadism (CHH): Large cohort analysis from a single tertiary centre

BACKGROUND

Congenital hypogonadotropic hypogonadism (CHH) is a condition with a strong genetic background, caused by a deficient production, secretion, or action of gonadotropin-releasing hormone (GnRH). Published data on CHH cohorts indicate a male predominance, although this is not supported by our current understandings.

AIMS

In order to unravel the possible causes or contributors to such epidemiological sex difference, the aim of our study is to investigate differences in genetic background and clinical presentation between males and females in a large cohort of CHH patients.

MATERIALS AND METHODS

We enrolled 338 CHH patients with absent or arrested pubertal development, referred to our Center from 01/2016. Data collection included clinical assessment at diagnosis and genetic analysis performed by next generation sequencing (NGS), employing a custom panel of 28 candidate genes.

RESULTS

Among 338 patients 94 were female (F) and 244 male (M), with a ratio of 1:2.6. We found that 36.09% (122/338) of patients harbored potentially pathogenic rare genetic variants (RVs) with no significant differences between sexes; on the other hand, a significantly higher frequency of oligogenicity was observed in females (F 9,57% 9/94 vs M 3,69% 9/244, P = 0.034). The prevalence of non-reproductive phenotypic features was significantly higher (P = 0.01) in males (53/228, 23.2%) than in females (10/93, 10.8%): in particular, kidney abnormalities affected only male patients and midline defects had a significantly higher prevalence in males (P = 0.010). Finally, BMI SDS was -0.04 ± 1.09 in females and 0.69 ± 1.51 in males, with a statistically significant difference between groups (P = <0.001).

CONCLUSION

Our data confirm the male predominance in CHH and identify some differences with regard to the clinical presentation between males and females that could indicate a variable expression of genetic rare variants and a dimorphic modulation of phenotype according to metabolic/behavioral factors, which will need to be substantiated and investigated by further studies.

Current concepts surrounding neonatal hormone therapy for boys with congenital hypogonadotropic hypogonadism

INTRODUCTION

Congenital hypogonadotropic hypogonadism (CHH) is a genetic disorder of reproduction and development, characterized by deficient gonadotropin-releasing hormone (GnRH) secretion or action, affecting 1-in-4,000-15,000 males. Micropenis and undescended testes are cardinal features of antenatal GnRH deficiency and could indicate absent minipuberty in the first postnatal months. In this review, we outline the pathophysiology and clinical consequences of absent minipuberty and its implications for optimal approaches to the endocrine management of affected boys.

AREAS COVERED

Deficient GnRH activity during fetal development and neonatal-infancy phase of minipuberty accounts for the diminished mass of Sertoli cells and seminiferous tubules among CHH males, enduring impairment of reproductive function even during gonadotropin replacement in adult life. In overcoming this obstacle, several clinical studies of neonatal gonadotropin replacement have consistently shown positive results in inducing testicular development and correcting cryptorchidism.

EXPERT OPINION

A high index of clinical suspicion, combined with hormonal testing undertaken in the postnatal period of 1-4 months, can reliably confirm or refute the diagnosis of CHH. Timely identification of CHH in affected male infants (having characteristic "red flag' developmental anomalies) opens up the possibility for gonadotropin replacement as a targeted therapy to restore the normal hormonal milieu of minipuberty. Further work is necessary in formulating optimal gonadotropin treatment regimens to be more widely adopted in clinical practice.

Genetics of hypogonadotropic Hypogonadism-Human and mouse genes, inheritance, oligogenicity, and genetic counseling

Hypogonadotropic hypogonadism, which may be normosmic (nHH) or anosmic/hyposmic, known as Kallmann syndrome (KS), is due to gonadotropin-releasing hormone deficiency, which results in absent puberty and infertility. Investigation of the genetic basis of nHH/KS over the past 35 years has yielded a substantial increase in our understanding, as variants in 44 genes in OMIM account for ~50% of cases. The first genes for KS (ANOS1) and nHH (GNRHR) were followed by the discovery that FGFR1 variants may cause either nHH or KS. Associated anomalies include midline facial defects, neurologic deficits, cardiac anomalies, and renal agenesis, among others. Mouse models for all but one gene (ANOS1) generally support findings in humans. About half of the known genes implicated in nHH/KS are inherited as autosomal dominant and half are autosomal recessive, whereas only 7% are X-linked recessive. Digenic and oligogenic inheritance has been reported in 2-20% of patients, most commonly with variants in genes that may result in either nHH or KS inherited in an autosomal dominant fashion. In vitro analyses have only been conducted for both gene variants in eight cases and for one gene variant in 20 cases. Rigorous confirmation that two gene variants in the same individual cause the nHH/KS phenotype is lacking for most. Clinical diagnosis is probably best accomplished by targeted next generation sequencing of the known candidate genes with confirmation by Sanger sequencing. Elucidation of the genetic basis of nHH/KS has resulted in an enhanced understanding of this disorder, as well as normal puberty, which makes genetic diagnosis clinically relevant.

Advances in Genetic Diagnosis of Kallmann Syndrome and Genetic Interruption

Kallmann syndrome (KS) is a rare hereditary disease with high phenotypic and genetic heterogeneity. Congenital hypogonadotropic hypogonadism and hyposmia/anosmia are the two major characterized phenotypes of KS. Besides, mirror movements, dental agenesis, digital bone abnormalities, unilateral renal agenesis, midline facial defects, hearing loss, and eye movement abnormalities can also be observed in KS patients. Because of the phenotypic heterogeneity, genetic diagnosis become increasingly valuable to distinguish KS from other disorders including normosmic congenital hypogonadotropic hypogonadism, constitutional delay of growth and puberty, CHARGE syndrome, and functional hypogonadotropic hypogonadism. Application of next-generation sequencing has promoted the discovery of novel pathogenic genes in KS pedigrees. Prenatal diagnosis is an effective method in clinical settings to decrease birth defects and block transmission of genetic disorders. However, pregnant women may suffer from physical and psychological distress when fetuses are diagnosed with congenital defects. Preimplantation genetic testing (PGT) is a prospective approach during the in vitro fertilization process that helps to interrupt transmission of hereditary diseases to offspring at an early stage. Thus, genetic testing and counseling are recommended to KS patients with family histories, prenatal diagnosis and PGT are considered to be useful options.

Clinical characteristics and molecular genetic analysis of a cohort with idiopathic congenital hypogonadism

OBJECTIVES

Hypogonadism is defined as inadequate sex hormone production due to defects in the hypothalamic-pituitary-gonadal axis. In recent years, rare single gene defects have been identified in both hypergonadotropic hypogonadism (Hh), and hypogonadotropic hypogonadism (HH) cases with no chromosomal anomalies. The aim of the present study is to investigate the underlying molecular genetic etiology and the genotype-phenotype relationship of a series of patients with Hh and HH.

METHODS

In total, 27 HH and six Hh cases were evaluated. Clinical and laboratory features are extracted from patients' hospital files. Whole exome sequencing (WES) analysis was performed.

RESULTS

A total of 27 HH cases (15 female) (mean age: 15.8 ± 2.7 years) and six Hh patients (six females) (mean age: 14.9 ± 1.2 years) were included. In molecular genetic analysis, a pathogenic/likely pathogenic variant was identified in five (two patients from the same family) of 27 HH cases (two novel) and three of the six Hh. In HH group variants (pathogenic, likely pathogenic and variant of uncertain significance) were identified in KISS1R (n=2), PROK2 (n=1), FGFR1 (n=1), HS6ST1 (n=1), GNRH1 (n=1) genes. In the Hh group, splice-site mutations were detected in DCAF17 (n=1) and MCM9 (n=2) genes.

CONCLUSIONS

HH and Hh cases are genetically heterogeneous diseases due to oligogenic inheritance, incomplete penetrance, and variable expressivity. We found rare variants in CHH related genes in half of our HH cases, whereas they classified as pathogenic/likely pathogenic according to ACMG criteria in only about 15% of HH cases. Using advanced genetic analysis methods such as whole-genome sequencing and long-read sequencing may increase the mutation detection rate, which should always be associated with and expert genetic counseling to interpret the data.

Defects in GnRH Neuron Migration/Development and Hypothalamic-Pituitary Signaling Impact Clinical Variability of Kallmann Syndrome

Kallmann syndrome (KS) is a combination of isolated hypogonadotropic hypogonadism (IHH) with olfactory dysfunction, representing a heterogeneous disorder with a broad phenotypic spectrum. The genetic background of KS has not yet been fully established. This study was conducted on 46 Polish KS subjects (41 males, 5 females; average age: 29 years old). The studied KS patients were screened for defects in a 38-gene panel with next-generation sequencing (NGS) technology. The analysis revealed 27 pathogenic and likely pathogenic (P/LP) variants, and 21 variants of uncertain significance (VUS). The P/LP variants were detected in 20 patients (43.5%). The prevalence of oligogenic P/LP defects in selected genes among KS patients was 26% (12/46), whereas the co-occurrence of other variants was detected in 43% (20 probands). The examined KS patients showed substantial genotypic and phenotypic variability. A marked difference in non-reproductive phenotypes, involving defects in genes responsible for GnRH neuron development/migration and genes contributing to pituitary development and signaling, was observed. A comprehensive gene panel for IHH testing enabled the detection of clinically relevant variants in the majority of KS patients, which makes targeted NGS an effective molecular tool. The significance of oligogenicity and the high incidence of alterations in selected genes should be further elucidated.

Recent advances in understanding and managing Kallmann syndrome

Many of the recent advances in our understanding of human reproductive biology and its genetic basis have arisen directly via the genetic investigation of patients with Kallmann syndrome and their families. The disease is characterised by the association of an isolated defect in the secretion (or, less commonly, action) of gonadotropin-releasing hormone (GnRH) and consequent infertility, with anosmia and potentially other associated non-reproductive features. GnRH-producing neurons are located in the hypothalamic brain region after a peculiar migration during embryonic life. To date, different genes affecting GnRH neuron development/migration have so far been implicated in Kallmann syndrome, but our knowledge of the genetic basis of the syndrome remains incomplete. From a clinical point of view, the disease has suffered from a lack of definitive diagnosis and treatment, and although progress has been made in terms of timely diagnosis and evidence-based treatment of patients, implementation remains inconsistent. These aspects will be discussed in this review, which examines new strategies for arriving at more evidence-based and patient-centred medical practice in Kallmann syndrome.

Central hypogonadism in Klinefelter syndrome: report of two cases and review of the literature

PURPOSE

Klinefelter syndrome (KS) is characterized by late adolescence/young adulthood onset of primary hypogonadism. Hypogonadotropic hypogonadism (HH), when congenital, is usually associated with absent/incomplete puberty and low/normal gonadotropins. We report the clinical and genetic features of two subjects with KS and an unexpected HH hormone profile.

METHODS

Magnetic resonance imaging (MRI) of hypothalamus-pituitary region and next generation sequencing (NGS) of congenital HH-associated genes were obtained. A narrative review of the literature was conducted.

RESULTS

Patients were diagnosed with Klinefelter syndrome following karyotype analysis. Nevertheless, they showed unusual features: both had incomplete puberty, low gonadotropins and testosterone levels, and the first one was anosmic. Sellar lesions were excluded by MRI, and NGS was negative in both subjects. Our data add to those of the only 14 similar cases reported so far. Unexplained HH rarely occurs in KS and is variably associated with anosmia, other pituitary hormones deficiencies and heterogeneous karyotypes. However, most cases show an early, pre-pubertal onset of hypogonadism. If the causes behind this gonadotropins defect are largely unknown, hereby we provide the first review of the literature on this topic and propose some pathogenetic hypotheses, including the coexistence of KS and congenital HH as suggested by overlapping clinical features in some of these patients.

CONCLUSION

HH is an exceptional occurrence in Klinefelter syndrome and is associated with heterogeneous phenotypes and, probably, aetiologies. Moreover, KS could underlie HH nonresponsive to gonadotropins. An exhaustive diagnostic workup and a tailored clinical management are advisable in these rare forms.

Does Proteomic Mirror Reflect Clinical Characteristics of Obesity?

Obesity is a frightening chronic disease, which has tripled since 1975. It is not expected to slow down staying one of the leading cases of preventable death and resulting in an increased clinical and economic burden. Poor lifestyle choices and excessive intake of “cheap calories” are major contributors to obesity, triggering type 2 diabetes, cardiovascular diseases, and other comorbidities. Understanding the molecular mechanisms responsible for development of obesity is essential as it might result in the introducing of anti-obesity targets and early-stage obesity biomarkers, allowing the distinction between metabolic syndromes. The complex nature of this disease, coupled with the phenomenon of metabolically healthy obesity, inspired us to perform data-centric, hypothesis-generating pilot research, aimed to find correlations between parameters of classic clinical blood tests and proteomic profiles of 104 lean and obese subjects. As the result, we assembled patterns of proteins, which presence or absence allows predicting the weight of the patient fairly well. We believe that such proteomic patterns with high prediction power should facilitate the translation of potential candidates into biomarkers of clinical use for early-stage stratification of obesity therapy.

Eight rare urinary disorders in a patient with Kallmann syndrome: A case report

RATIONALE

Kallmann syndrome (KS) is a rare inherited genetic disorder characterized by hypogonadotropic hypogonadism and hyposmia/anosmia. Early diagnosis is the key to timely treatment and improvement of prognosis in patients with KS. As the most common complication of KS, renal agenesis can provide clues to early diagnosis and treatment for KS. In this article, we report a case of KS with 8 rare urinary disorders for the first time.

PATIENT CONCERNS

A 19-year-old Chinese man presented with 8 rare urinary disorders and a history of bilateral cryptorchidism came to us for micropenis, hyposmia, and delayed puberty.

DIAGNOSIS

The patient presented with hyposmia, low levels of sex hormones and showed a weak response to the GnRH stimulation test leading to a diagnosis of KS. Two missense mutations were found in further whole-exome sequencing: 1) Kallmann syndrome 1 (KAL1) gene in exon11, c.1600G > A, p. Val534Ile; 2) Prokineticin receptor 2 (PROKR2) gene in exon 2, c.533G > A, p. Trp178Ser. which led to a diagnosis of KS.

INTERVENTIONS

The patient underwent replacement therapy of human chorionic gonadotropin (HCG) and human menopausal gonadotropin (HMG). The patient had previously undergone six surgeries for cryptorchidism and urinary disorders.

OUTCOMES

The patient's puberty retardation was effectively alleviated. His serum testosterone (T) reached a normal level (8.280 nmol/mL). During the follow-up period, he presented with Tanner stage II pubic hair development.

CONCLUSION

In this article, we report 8 rare urinary disorders with missense mutations of KAL1 and PROKR2 in a case of KS. Among them, bilateral giant kidneys, urinary extravasation of right renal, bilateral megalo-ureters, left ureteral terminal obstruction, bilateral renal cyst and bladder emptying disorder are reported for the first time, which enrich the integrity of urinary disorder types and provide clues to genetic counseling in patients with KS.

A novel SOX10 variant in a Japanese girl with Waardenburg syndrome type 4C and Kallmann syndrome

We report the first case of Waardenburg syndrome type 4C and Kallmann syndrome in the same person. The patient, a Japanese girl, presented with bilateral iris depigmentation, bilateral sensorineural hearing loss, Hirschsprung disease, hypogonadotropic hypogonadism, and anosmia. We identified a novel SOX10 variant, c.124delC, p.Leu42Cysfs*67.

Identification of two novel mutations in three Chinese families with Kallmann syndrome using whole exome sequencing

Kallmann syndrome (KS) is a rare developmental disorder that manifests as congenital hypogonadotropic hypogonadism with anosmia. More than 19 genes have been found to be associated with KS. However, approximately 70% of the causes of KS remain unclear. Here, we studied seven KS patients, from three families, who had delayed puberty and olfactory bulb dysplasia. However, the families of these patients showed a range of other unique clinical features, including hearing loss, anosmia (to varying degrees) and unilateral renal agenesis. We performed whole exome sequencing and copy number variation (CNV) sequencing on samples acquired from these patients. We identified two novel mutations (c.844delC in ANOS1, c.475C>T in SOX10) and a novel trigenic pattern, PROKR2/CHD7/FEZF1 (c.337T>C in PROKR2, c.748C>G in FEZF1, c.8773G>A in CHD7). The c.844delC mutation in the ANOS1 gene was predicted to generate a truncated form of the anosmin-1 protein. SIFT and PolyPhen-2 predicted that the c.475C>T mutation in SOX10 had a damaging effect. The PROKR2 mutation (c.337T>C) was previously reported as harmful. No pathogenic copy number alterations were detected. Our study expands the genotypic and phenotypic spectrum of KS, a disease that shows considerable clinical and genetic heterogeneity. The application of whole exome sequencing could facilitate our understanding of the pathogenesis of KS.

Prevalence and associated phenotypes of DUSP6, IL17RD and SPRY4 variants in a large Chinese cohort with isolated hypogonadotropic hypogonadism

BACKGROUND

FGF8-FGFR1 signalling is involved in multiple biological processes, while impairment of this signalling is one of the main reasons for isolated hypogonadotropic hypogonadism (IHH). Recently, several negative modulators of FGF8-FGFR1 signalling were also found to be involved in IHH, including DUSP6, IL17RD, SPRY2 and SPRY4. The aim of this study was to investigate the genotypic and phenotypic spectra of these genes in a large cohort of Chinese patients with IHH.

METHODS

A total of 196 patients with IHH were enrolled in this study. Whole-exome sequencing was performed to identify variants, which was verified by PCR and Sanger sequencing.

RESULTS

Four heterozygous DUSP6 variants (p.S157I, p.R83Q, p.P188L and p.N355I) were found in six patients. Cryptorchidism, dental agenesis, syndactyly and blue colour blindness were commonly observed in patients with DUSP6 mutations. Six heterozygous IL17RD variants (p.P191L, p.G35V, p.S671L, p.A221T, p.I329M and p.I329V) were found in seven patients. Segregation analysis indicated that 100% (5/5) of probands inherited the IL17RD variants from their unaffected parents, and oligogenicity was found in 4/7 patients. One rare SPRY4 variant (p.T68S) was found in a female patient with Kallmann syndrome who also carried a PLXNA1 mutation.

CONCLUSION

Our study greatly enriched the genotypic and phenotypic spectra of DUSP6, IL17RD and SPRY4 in IHH. Mutations in DUSP6 alone seem sufficient to cause IHH in an autosomal dominant manner, whereas IL17RD or SPRY4 mutations may cause IHH phenotypes in synergy with variants in other IHH-associated genes.

Insight Into the Ontogeny of GnRH Neurons From Patients Born Without a Nose

CONTEXT

The reproductive axis is controlled by a network of gonadotropin-releasing hormone (GnRH) neurons born in the primitive nose that migrate to the hypothalamus alongside axons of the olfactory system. The observation that congenital anosmia (inability to smell) is often associated with GnRH deficiency in humans led to the prevailing view that GnRH neurons depend on olfactory structures to reach the brain, but this hypothesis has not been confirmed.

OBJECTIVE

The objective of this work is to determine the potential for normal reproductive function in the setting of completely absent internal and external olfactory structures.

METHODS

We conducted comprehensive phenotyping studies in 11 patients with congenital arhinia. These studies were augmented by review of medical records and study questionnaires in another 40 international patients.

RESULTS

All male patients demonstrated clinical and/or biochemical signs of GnRH deficiency, and the 5 men studied in person had no luteinizing hormone (LH) pulses, suggesting absent GnRH activity. The 6 women studied in person also had apulsatile LH profiles, yet 3 had spontaneous breast development and 2 women (studied from afar) had normal breast development and menstrual cycles, suggesting a fully intact reproductive axis. Administration of pulsatile GnRH to 2 GnRH-deficient patients revealed normal pituitary responsiveness but gonadal failure in the male patient.

CONCLUSIONS

Patients with arhinia teach us that the GnRH neuron, a key gatekeeper of the reproductive axis, is associated with but may not depend on olfactory structures for normal migration and function, and more broadly, illustrate the power of extreme human phenotypes in answering fundamental questions about human embryology.

Genetics of congenital hypogonadotropic hypogonadism: peculiarities and phenotype of an oligogenic disease

A genetic basis of congenital isolated hypogonadotropic hypogonadism (CHH) can be defined in almost 50% of cases, albeit not necessarily the complete genetic basis. Next-generation sequencing (NGS) techniques have led to the discovery of a great number of loci, each of which has illuminated our understanding of human gonadotropin-releasing hormone (GnRH) neurons, either in respect of their embryonic development or their neuroendocrine regulation as the "pilot light" of human reproduction. However, because each new gene linked to CHH only seems to underpin another small percentage of total patient cases, we are still far from achieving a comprehensive understanding of the genetic basis of CHH. Patients have generally not benefited from advances in genetics in respect of novel therapies. In most cases, even genetic counselling is limited by issues of apparent variability in expressivity and penetrance that are likely underpinned by oligogenicity in respect of known and unknown genes. Robust genotype-phenotype relationships can generally only be established for individuals who are homozygous, hemizygous or compound heterozygotes for the same gene of variant alleles that are predicted to be deleterious. While certain genes are purely associated with normosmic CHH (nCHH) some purely with the anosmic form (Kallmann syndrome-KS), other genes can be associated with both nCHH and KS-sometimes even within the same kindred. Even though the anticipated genetic overlap between CHH and constitutional delay in growth and puberty (CDGP) has not materialised, previously unanticipated genetic relationships have emerged, comprising conditions of combined (or multiple) pituitary hormone deficiency (CPHD), hypothalamic amenorrhea (HA) and CHARGE syndrome. In this review, we report the current evidence in relation to phenotype and genetic peculiarities regarding 60 genes whose loss-of-function variants can disrupt the central regulation of reproduction at many levels: impairing GnRH neurons migration, differentiation or activation; disrupting neuroendocrine control of GnRH secretion; preventing GnRH neuron migration or function and/or gonadotropin secretion and action.

Genetic Evaluation of Patients With Delayed Puberty and Congenital Hypogonadotropic Hypogonadism: Is it Worthy of Consideration?

Delayed puberty is a common reason of pediatric endocrinological consultation. It is often a self-limited (or constitutional) condition with a strong familial basis. The type of inheritance is variable but most commonly autosomal dominant. Despite this strong genetic determinant, mutations in genes implicated in the regulation of hypothalamic-pituitary-gonadal axis have rarely been identified in cases of self-limited delayed puberty and often in relatives of patients with congenital hypogonadotropic hypogonadism (i.e., FGFR1 and GNRHR genes). However, recently, next-generation sequencing analysis has led to the discovery of new genes (i.e., IGSF10, HS6ST1, FTO, and EAP1) that are implicated in determining isolated self-limited delayed puberty in some families. Despite the heterogeneity of genetic defects resulting in delayed puberty, genetic testing may become a useful diagnostic tool for the correct classification and management of patients with delayed puberty. This article will discuss the benefits and the limitations of genetic testing execution in cases of delayed puberty.

GnRH Deficient Patients With Congenital Hypogonadotropic Hypogonadism: Novel Genetic Findings in ANOS1, RNF216, WDR11, FGFR1, CHD7, and POLR3A Genes in a Case Series and Review of the Literature

Background: Congenital hypogonadotropic hypogonadism (CHH) is a rare genetic disease caused by Gonadotropin-Releasing Hormone (GnRH) deficiency. So far a limited number of variants in several genes have been associated with the pathogenesis of the disease. In this original research and review manuscript the retrospective analysis of known variants in ANOS1 (KAL1), RNF216, WDR11, FGFR1, CHD7, and POLR3A genes is described, along with novel variants identified in patients with CHH by the present study. Methods: Seven GnRH deficient unrelated Cypriot patients underwent whole exome sequencing (WES) by Next Generation Sequencing (NGS). The identified novel variants were initially examined by in silico computational algorithms and structural analysis of their predicted pathogenicity at the protein level was confirmed. Results: In four non-related GnRH males, a novel X-linked pathogenic variant in ANOS1 gene, two novel autosomal dominant (AD) probably pathogenic variants in WDR11 and FGFR1 genes and one rare AD probably pathogenic variant in CHD7 gene were identified. A rare autosomal recessive (AR) variant in the SRA1 gene was identified in homozygosity in a female patient, whilst two other male patients were also, respectively, found to carry novel or previously reported rare pathogenic variants in more than one genes; FGFR1/POLR3A and SRA1/RNF216. Conclusion: This report embraces the description of novel and previously reported rare pathogenic variants in a series of genes known to be implicated in the biological development of CHH. Notably, patients with CHH can harbor pathogenic rare variants in more than one gene which raises the hypothesis of locus-locus interactions providing evidence for digenic inheritance. The identification of such aberrations by NGS can be very informative for the management and future planning of these patients.

Genotypic and phenotypic spectra of FGFR1, FGF8, and FGF17 mutations in a Chinese cohort with idiopathic hypogonadotropic hypogonadism

OBJECTIVE

To analyze the prevalence of FGFR1, FGF8, and FGF17 mutations in a Chinese cohort with idiopathic hypogonadotropic hypogonadism (IHH) and to characterize the clinical presentations and therapeutic outcomes of IHH patients with FGFR1, FGF8, and FGF17 mutations.

DESIGN

Retrospective cohort.

SETTING

University hospital.

PATIENT(S)

A total of 145 IHH probands (125 men and 20 women) were recruited for this study.

INTERVENTIONS(S)

Hormone assays.

MAIN OUTCOME MEASURE(S)

Whole-exome sequencing, polymerase chain reaction-Sanger sequencing, in silico functional prediction.

RESULT(S)

Six novel mutations (p.154_158del, p.E496Rfs*12, p.W190X, p.S134D, p.W10X, and c.1552 + 3insT) in FGFR1, two novel mutations (p.E176K and p.R184C) in FGF8, three novel mutations (p.48_52del, p.P120L, and p.K191R) in FGF17, and five reported mutations (p.W289X, p.G237S, p.V102I, p.R250Q, and p.T340M) in FGFR1 were identified in 18 IHH patients. The functional consequences of all mutations were analyzed in silico. In addition to hypogonadotropic hypogonadism, 44.4% (8/18) patients exhibited other clinical deformities, including dental agenesis (3/18, 16.7%), hearing loss (3/18, 16.7%), and hand malformation (2/18, 11.1%). hCG/hMG therapy was effective in promoting sexual development in IHH patients with FGFR1, FGF8, and FGF17 mutations.

CONCLUSION(S)

We extended the mutational spectrum of FGFR1, FGF8, and FGF17 in IHH patients. The prevalence of FGFR1, FGF8, and FGF17 mutations in IHH was 12.4%. hCG/hMG therapy was effective to acquire fertility for patients with FGFR1, FGF8, and FGF17 mutations but has a risk of transmitting the mutations and IHH to the next generation.

Nasal Placode Development, GnRH Neuronal Migration and Kallmann Syndrome

The development of Gonadotropin releasing hormone-1 (GnRH) neurons is important for a functional reproduction system in vertebrates. Disruption of GnRH results in hypogonadism and if accompanied by anosmia is termed Kallmann Syndrome (KS). From their origin in the nasal placode, GnRH neurons migrate along the olfactory-derived vomeronasal axons to the nasal forebrain junction and then turn caudally into the developing forebrain. Although research on the origin of GnRH neurons, their migration and genes associated with KS has identified multiple factors that influence development of this system, several aspects still remain unclear. This review discusses development of the olfactory system, factors that regulate GnRH neuron formation and development of the olfactory system, migration of the GnRH neurons from the nose into the brain, and mutations in humans with KS that result from disruption of normal GnRH/olfactory systems development.

Replacement of Male Mini-Puberty

Context

Clinical management of congenital hypogonadotropic hypogonadism (CHH) remains a challenge in pediatric endocrinology.

Objective

To investigate whether daily subcutaneous injections of the recombinant human LH/FSH preparation could mimic the physiological male mini-puberty.

Design and Setting

The REMAP (REplacement of MAle mini-Puberty) study with up to 10 years of follow-up.

Patients and Intervention

Ten neonates or infants, all with bilateral cryptorchidism in intra-abdominal/inguinal position and micropenis with the absence of neonatal male mini-puberty, received daily subcutaneous injections of Pergoveris^® (LH/FSH 75/150 IU) for 3 months.

Main Outcome Measures

Restoration of bilateral cryptorchidism/micropenis and the Leydig/Sertoli cells function.

Results

At the end of treatment, median LH and FSH, both undetectable before treatment, reached high normal levels of 4.45 IU/L and supranormal levels 83 IU/L, respectively; median inhibin-b and anti-Mullerian hormone levels increased from subnormal (27.8 and 1.54 ng/mL, respectively) to normal levels (365 and 150 ng/mL, respectively); median testosterone increased from just detectable (0.02 ng/mL) to normal levels (3.3 ng/mL). Stretched penile length increased from a median of 2 to 3.8 cm. During therapy, all testes descended to the scrotal position (by the end of the first month in three patients, the second month in four patients, and the third month in three patients), measuring 1.5 mL and appearing normal in ultrasonography. Three infants received additional treatment with testosterone enanthate. In two infants, one of two testes regressed in the low inguinal area; both infants were successfully treated surgically. After 1 to 10 years of follow-up, all testes are still in scrotal position and have slightly regressed in size.

Conclusions

The proposed regimen mimics neonatal male mini-puberty and successfully treats infants with micropenis and cryptorchidism in CHH.

Next-generation sequencing refines the genetic architecture of Greek GnRH-deficient patients

Isolated gonadotropin-releasing hormone (GnRH) deficiency (IGD) is a rare disease with a wide spectrum of reproductive and non-reproductive clinical characteristics. Apart from the phenotypic heterogeneity, IGD is also highly genetically heterogeneous with >35 genes implicated in the disease. Despite this genetic heterogeneity, genetic enrichment in specific subpopulations has been described. We have previously described low prevalence of genetic variation in the Greek IGD cohort discovered with utilization of Sanger sequencing in 14 known IGD genes. Here, we describe the expansion of genetic screening in the largest IGD Greek cohort that has ever been studied with the usage of whole-exome sequencing, searching for rare sequencing variants (RSVs) in 37 known IGD genes. Even though Sanger sequencing detected genetic variation in 21/81 IGD patients in 7/14 IGD genes without any evidence of oligogenicity, whole exome sequencing (WES) revealed that 27/87 IGD patients carried a rare genetic change in a total of 15 genes with 4 IGD cases being oligogenic. Our findings suggest that next-generation sequencing (NGS) techniques can discover previously undetected variation, making them the standardized method for screening patients with rare and/or more common disorders.

Clinical Management of Congenital Hypogonadotropic Hypogonadism

The initiation and maintenance of reproductive capacity in humans is dependent on pulsatile secretion of the hypothalamic hormone GnRH. Congenital hypogonadotropic hypogonadism (CHH) is a rare disorder that results from the failure of the normal episodic GnRH secretion, leading to delayed puberty and infertility. CHH can be associated with an absent sense of smell, also termed Kallmann syndrome, or with other anomalies. CHH is characterized by rich genetic heterogeneity, with mutations in >30 genes identified to date acting either alone or in combination. CHH can be challenging to diagnose, particularly in early adolescence where the clinical picture mirrors that of constitutional delay of growth and puberty. Timely diagnosis and treatment will induce puberty, leading to improved sexual, bone, metabolic, and psychological health. In most cases, patients require lifelong treatment, yet a notable portion of male patients (∼10% to 20%) exhibit a spontaneous recovery of their reproductive function. Finally, fertility can be induced with pulsatile GnRH treatment or gonadotropin regimens in most patients. In summary, this review is a comprehensive synthesis of the current literature available regarding the diagnosis, patient management, and genetic foundations of CHH relative to normal reproductive development.

Unilateral renal agenesis as an early marker for genetic screening in Kallmann syndrome

Isolated GnRH Deficiency (IGD) that is either displayed as Kallmann Syndrome (KS) or normosmic idiopathic hypogonadotropic hypogonadism (nIHH) is a rare Mendelian disorder with wide clinical and genetic variability. Apart from the arrest of pubertal development, IGD is also characterized by a variety of non- reproductive features including unilateral renal agenesis (URA), midline defects, dental & ocular defects and many more. In this analysis we explored the role of unilateral renal agenesis, as a screening tool for detection of genetic changes associated with IGD. We performed detailed genetic screening with Sanger sequencing in 14 genes associated with Isolated GnRH Deficiency as well as screening of intragenic deletions in the gene of anosmin 1-ANOS1 with MLPA. No genetic variation was detected, suggestive of an alternative genetic cause for URA in these normosmic patients, highlighting the necessity of further genetic screening.

Mutation profiles and clinical characteristics of Chinese males with isolated hypogonadotropic hypogonadism

OBJECTIVE

To investigate the mutation profiles and clinical characteristics of Chinese males with isolated hypogonadotropic hypogonadism (IHH) and discover new pathogenic genes that cause IHH.

DESIGN

A gene panel, including 31 known IHH genes and 52 candidate genes, was used to perform semiconductor next-generation sequencing.

SETTING

University hospital.

PATIENTS

One hundred thirty-eight sporadic male IHH patients and 10 IHH families; 100 healthy men with normal fertility served as control subjects.

INTERVENTIONS(S)

None.

MAIN OUTCOME MEASURE(S)

Targeted next-generation sequencing, polymerase chain reaction and sequencing, pedigree analysis, and bioinformatics analysis.

RESULT(S)

Variants were distributed uniformly throughout 52 genes (52/83, 62.65%), including 16 (16/31, 51.61%) causal genes and 36 (36/52, 69.23%) candidate genes. Six new pathogenic variants and 52 likely pathogenic variants were identified in 16 genes known to cause nIHH/KS (normosmic IHH/Kallmann syndrome). In the 148 probands, PROKR2 (22/148, 14.86%), CHD7, FGFR1, and KAL1 had high mutation rates, and 8.78% (13/148) of the patients carried at least two variants in known genes. In addition, variants were identified in 36 candidate genes, and EGFR, ERBB4, PAX6, IGF1, SEMA4D, and SEMA7A should be prioritized for further research and genetic testing in IHH.

CONCLUSION(S)

The mutation frequency of IHH-causal genes in Chinese HAN males was different from the data reported in white populations. Oligogenic inheritance was a common phenomenon in IHH. Our study expands the mutation profile for IHH, and the new likely pathogenic genes identified in our study warrant further research in GnRH neuronal networks.

Evidence for a Common Genetic Origin of Classic and Milder Adult-Onset Forms of Isolated Hypogonadotropic Hypogonadism

Multiple metabolic and inflammatory mechanisms are considered the determinants of acquired functional isolated hypogonadotropic hypogonadism (IHH) in males, whereas classic IHH is a rare congenital condition with a strong genetic background. Since we recently uncovered a frequent familiarity for classic IHH among patients with mild adult-onset hypogonadism (AO-IHH), here we performed a genetic characterization by next generation sequencing of 160 males with classic or “functional” forms. The prevalence of rare variants in 28 candidate genes was significantly higher than in controls in all IHH patients, independently of the age of IHH onset, degree of hypogonadism or presence of obesity. In fact, it did not differ among patients with classic or milder forms of IHH, however particular genes appear to be more specifically associated with one or the other category of IHH. ROC curves showed that Total Testosterone <6.05 nmol/L and an age of onset <41 years are sensitive cutoffs to identify patients with significantly higher chances of harboring rare IHH gene variants. In conclusion, rare IHH genes variants can frequently predispose to AO-IHH with acquired mild hormonal deficiencies. The identification of a genetic predisposition can improve the familial and individual management of AO-IHH and explain the heritability of congenital IHH.

Congenital Hypogonadotrophic Hypogonadism: Minipuberty and the Case for Neonatal Diagnosis

Congenital hypogonadotrophic hypogonadism (CHH) is a rare but important etiology of pubertal failure and infertility, resulting from impaired gonadotrophin-releasing hormone secretion or action. Despite the availability of effective hormonal therapies, the majority of men with CHH experience unsatisfactory outcomes, including chronic psychosocial and reproductive sequelae. Early detection and timely interventions are crucial to address the gaps in medical care and improve the outlook for these patients. In this paper, we review the clinical implications of missing minipuberty in CHH and therapeutic strategies that can modify the course of disease, as well as explore a targeted approach to identifying affected male infants by integrating clinical and biochemical data in the early postnatal months.

Managing congenital hypogonadotrophic hypogonadism: a contemporary approach directed at optimizing fertility and long-term outcomes in males

Hormonal induction of spermatogenesis offers men with azoospermia due to hypogonadotrophic hypogonadism (HH) the promising prospect of fertility restoration. However, an important exception is the subset of individuals affected by congenital hypogonadotrophic hypogonadism (CHH), also known as Kallmann syndrome if associated with anosmia, who often display dismal responses to fertility induction, despite prolonged therapy. This primarily stems from the loss of minipuberty, which is a crucial phase of testicular maturation in early life that has a far-reaching impact on eventual spermatogenic capacity. Further exacerbating the compromised reproductive health is the failure to initiate timely pubertal induction in many CHH patients, resulting in suboptimal genital and psychosexual development. In this paper, the clinical implications and management of male HH across the lifespan is comprehensively reviewed, with a special focus on novel strategies that have the potential to modify disease severity and maximize fertility potential in CHH by addressing the inadequacies of conventional approaches.

PROKR2 mutations in idiopathic hypogonadotropic hypogonadism: selective disruption of the binding to a Gα-protein leads to biased signaling

Idiopathic hypogonadotropic hypogonadism (IHH) is a rare disorder caused by the deficient production, secretion, or action of gonadotropin-releasing hormone. Prokineticin (PROK) receptor 2 ( PROKR2), a causative gene for IHH, encodes a GPCR PROKR2. When PROKR2 binds to its ligands PROKs, it may activate several signaling pathways, including IP3/Ca²⁺, MAPK, and cAMP pathways. However, the mutational spectrum of PROKR2 in Chinese patients with IHH has not been established. In the present study, we found that up to 13.3% (18/135) of patients with IHH in China carried mutations in PROKR2. Most of the variants in this study were private; however, a PROKR2 (c.533G > C; p.W178S) mutation was identified in 10 independent patients, implying a possible founder mutation. Functional studies indicated that 6 novel PROKR2 mutations led to decreased signaling to various extents. Two IHH-associated mutations (L218P and R270H) disrupted Gαq-dependent signaling but maintained normal Gαs and ERK1/2 signaling. A glutathione S-transferase pull-down experiment demonstrated that R270H mutation disrupted the interaction of intracellular loop 3 of PROKR2 to Gαq protein but not Gαs protein. Our results indicated that selective disruption of the interaction with a specific Gα-protein might underlie the biased signaling for certain IHH-associated PROKR2 mutations.-Zhao, Y., Wu, J., Jia, H., Wang, X., Zheng, R., Jiang, F., Chen, D.-N., Chen, Z., Li, J.-D. PROKR2 mutations in idiopathic hypogonadotropic hypogonadism: selective disruption of the binding to a Gα-protein leads to biased signaling.

Homeogene emx1 is required for nephron distal segment development in zebrafish

Vertebrate kidneys contain nephron functional units where specialized epithelial cell types are organized into segments with discrete physiological roles. Many gaps remain in our understanding of how segment regions develop. Here, we report that the transcription factor empty spiracles homeobox gene 1 (emx1) is a novel nephron segment regulator during embryonic kidney development in zebrafish. emx1 loss of function altered the domains of distal segments without changes in cell turnover or traits like size and morphology, indicating that emx1 directs distal segment fates during nephrogenesis. In exploring how emx1 influences nephron patterning, we found that retinoic acid (RA), a morphogen that induces proximal and represses distal segments, negatively regulates emx1 expression. Next, through a series of genetic studies, we found that emx1 acts downstream of a cascade involving mecom and tbx2b, which encode essential distal segment transcription factors. Finally, we determined that emx1 regulates the expression domains of irx3b and irx1a to control distal segmentation, and sim1a to control corpuscle of Stannius formation. Taken together, our work reveals for the first time that emx1 is a key component of the pronephros segmentation network, which has implications for understanding the genetic regulatory cascades that orchestrate vertebrate nephron patterning.

[Clinical and genetic features of Kallmann syndrome: an analysis of 5 cases]

Kallmann syndrome (KS) is a rare pediatric disease with major manifestations of olfactory dysfunction and hypogonadotropic hypogonadism. Five children (4 boys and 1 girl) with KS reported in this article were aged between 6 months and 19 years at the time when they attended the hospital. All the children had the clinical manifestation of hypogonadotropic hypogonadism; in addition, three children had olfactory dysfunction (two were found to have olfactory bulb dysplasia on magnetic resonance imaging), one had cleft lip and palate, and one had micropenis and cryptorchidism with right renal agenesis during infancy. All the five children had normal karyotype and their parents had normal clinical phenotypes. The uncle of one child had underdeveloped secondary sexual characteristics and olfactory disorder since childhood. High-throughput sequencing found two known heterozygous missense mutations in the FGFR1 gene, i.e., c.1097C>T(p.P366L) and c.809G>C(p.G270A), in two children. One child had a novel frameshift mutation, c.1877_1887/p.S627Tfs*6, in the KAL1 gene; this deletion mutation caused a frameshift in base sequence and produced truncated proteins, which led to a significant change in protein structure, and thus it was highly pathogenic. It is concluded that KS has great clinical and genetic heterogeneity and can be accompanied by incomplete dominant inheritance and that gene detection helps with the diagnosis of this disease.

Prokineticins and their G protein-coupled receptors in health and disease

Prokineticins are two conserved small proteins (~8kDa), prokineticin 1 (PROK1; also called EG-VEGF) and prokineticin 2 (PROK2; also called Bv8), with an N-terminal AVITGA sequence and 10 cysteines forming 5 disulfide bridges. PROK1 and PROK2 bind to two highly related G protein-coupled receptors (GPCRs), prokineticin receptor 1 (PROKR1) and prokineticin receptor 2 (PROKR2). Prokineticins and their receptors are widely expressed. PROK1 is predominantly expressed in peripheral tissues, especially steroidogenic organs, whereas PROK2 is mainly expressed in the central nervous system and nonsteroidogenic cells of the testes. Prokineticins signaling has been implicated in several important physiological functions, including gastrointestinal smooth muscle contraction, circadian rhythm regulation, neurogenesis, angiogenesis, pain perception, mood regulation, and reproduction. Dysregulation of prokineticins signaling has been observed in a variety of diseases, such as cancer, ischemia, and neurodegeneration, in which prokineticins signaling seems to be a promising therapeutic target. Based on the phenotypes of knockout mice, PROKR2 and PROK2 have recently been identified as causative genes for idiopathic hypogonadotropic hypogonadism, a developmental disorder characterized by impaired development of gonadotropin-releasing hormone neurons and infertility. In vitro functional studies with these disease-associated PROKR2 mutations uncovered some novel features for this receptor, such as biased signaling, which may be used to understand GPCR signaling regulation in general.

Kallmann syndrome: phenotype and genotype of hypogonadotropic hypogonadism

Isolated Gonadotropin-Releasing Hormone (GnRH) Deficiency (IGD) IGD is a genetically and clinically heterogeneous disorder. Mutations in many different genes are able to explain ~40% of the causes of IGD, with the rest of cases remaining genetically uncharacterized. While most mutations are inherited in X-linked, autosomal dominant, or autosomal recessive pattern, several IGD genes are shown to interact with each other in an oligogenic manner. In addition, while the genes involved in the pathogenesis of IGD act on either neurodevelopmental or neuroendocrine pathways, a subset of genes are involved in both pathways, acting as "overlap genes". Thus, some IGD genes play the role of the modifier genes or "second hits", providing an explanation for incomplete penetrance and variable expressivity associated with some IGD mutations. The clinical spectrum of IGD includes a variety of disorders including Kallmann Syndrome (KS), i.e. hypogonadotropic hypogonadism with anosmia, and its normosmic variation normosmic idiopathic hypogonadotropic hypogonadism (nIHH), which represent the most severe aspects of the disorder. Apart from these disorders, there are also "milder" and more common reproductive diseases associated with IGD, including hypothalamic amenorrhea (HA), constitutional delay of puberty (CDP) and adult-onset hypogonadotropic hypogonadism (AHH). Interestingly, neurodeveloplmental genes are associated with the KS form of IGD, due to the topographical link between the GnRH neurons and the olfactory placode. On the other hand, neuroendocrine genes are mostly linked to nIHH. However, a great deal of clinical and genetic overlap characterizes the spectrum of the IGD disorders. IGD is also characterized by a wide variety of non-reproductive features, including midline facial defects such as cleft lip and/or palate, renal agenesis, short metacarpals and other bone abnormalities, hearing loss, synkinesia, eye movement abnormalities, poor balance due to cerebellar ataxia, etc. Therefore, genetic screening should be offered in patients with IGD, as it can provide valuable information for genetic counseling and further understanding of IGD.

ANOS1: a unified nomenclature for Kallmann syndrome 1 gene (KAL1) and anosmin-1

It is accepted that confusion regarding the description of genetic variants occurs when researchers do not use standard nomenclature. The Human Genome Organization Gene Nomenclature Committee contacted a panel of consultants, all working on the KAL1 gene, to propose an update of the nomenclature of the gene, as there was a convention in the literature of using the ‘KAL1’ symbol, when referring to the gene, but using the name ‘anosmin-1’ when referring to the protein. The new name, ANOS1, reflects protein name and is more transferrable across species.

GENETICS IN ENDOCRINOLOGY: Genetic counseling for congenital hypogonadotropic hypogonadism and Kallmann syndrome: new challenges in the era of oligogenism and next-generation sequencing

Congenital hypogonadotropic hypogonadism (CHH) and Kallmann syndrome (KS) are rare, related diseases that prevent normal pubertal development and cause infertility in affected men and women. However, the infertility carries a good prognosis as increasing numbers of patients with CHH/KS are now able to have children through medically assisted procreation. These are genetic diseases that can be transmitted to patients' offspring. Importantly, patients and their families should be informed of this risk and given genetic counseling. CHH and KS are phenotypically and genetically heterogeneous diseases in which the risk of transmission largely depends on the gene(s) responsible(s). Inheritance may be classically Mendelian yet more complex; oligogenic modes of transmission have also been described. The prevalence of oligogenicity has risen dramatically since the advent of massively parallel next-generation sequencing (NGS) in which tens, hundreds or thousands of genes are sequenced at the same time. NGS is medically and economically more efficient and more rapid than traditional Sanger sequencing and is increasingly being used in medical practice. Thus, it seems plausible that oligogenic forms of CHH/KS will be increasingly identified making genetic counseling even more complex. In this context, the main challenge will be to differentiate true oligogenism from situations when several rare variants that do not have a clear phenotypic effect are identified by chance. This review aims to summarize the genetics of CHH/KS and to discuss the challenges of oligogenic transmission and also its role in incomplete penetrance and variable expressivity in a perspective of genetic counseling.

Safety and tolerability of one-year intramuscular testosterone regime to induce puberty in older men with CHH

We present herein our 20-year experience of pubertal induction in apubertal older (median age 56 years; range 38.4-69.5) men with congenital hypogonadotrophic hypogonadism (n = 7) using a simple fixed-dose and fixed-interval intramuscular testosterone that we originally pioneered in relation to achieving virilisation of natal female transgender men. This regime was effective and well tolerated, resulting in complete virilisation by around 1 year after treatment initiation. No physical or psychological adverse effects were encountered in this group of potentially vulnerable individuals. There were no abnormal excursions of laboratory parameters and extended follow-up beyond the first year of treatment revealed remarkable improvements in bone density. We highlight advantages to both patients and physicians of this regime in testosterone-naïve older men with congenital hypogonadism and discourage the over-rigid application to such patients of treatment algorithms derived from paediatric practice in relation to the evaluation and management in younger teenagers with delayed puberty of uncertain cause.

Characteristics of a nationwide cohort of patients presenting with isolated hypogonadotropic hypogonadism (IHH)

OBJECTIVE

Isolated hypogonadotropic hypogonadism (IHH) is a rare disorder with pubertal delay, normal (normoosmic-IHH, nIHH) or defective sense of smell (Kallmann syndrome, KS). Other reproductive and non-reproductive anomalies might be present although information on their frequency are scanty, particularly according to the age of presentation.

DESIGN

Observational cohort study carried out between January 2008 and June 2016 within a national network of academic or general hospitals.

METHODS

We performed a detailed phenotyping of 503 IHH patients with: (1) manifestations of hypogonadism with low sex steroid hormone and low/normal gonadotropins; (2) absence of expansive hypothalamic/pituitary lesions or multiple pituitary hormone defects. Cohort was divided on IHH onset (PPO, pre-pubertal onset or AO, adult onset) and olfactory function: PPO-nIHH (n = 275), KS (n = 184), AO-nIHH (n = 36) and AO-doIHH (AO-IHH with defective olfaction, n = 8).

RESULTS

90% of patients were classified as PPO and 10% as AO. Typical midline and olfactory defects, bimanual synkinesis and familiarity for pubertal delay were also found among the AO-IHH. Mean age at diagnosis was significantly earlier and more frequently associated with congenital hypogonadism stigmata in patients with Kallmann's syndrome (KS). Synkinesis, renal and male genital tract anomalies were enriched in KS. Overweight/obesity are significantly associated with AO-IHH rather than PPO-IHH.

CONCLUSIONS

Patients with KS are more prone to develop a severe and complex phenotype than nIHH. The presence of typical extra-gonadal defects and familiarity for PPO-IHH among the AO-IHH patients indicates a common predisposition with variable clinical expression. Overall, these findings improve the understanding of IHH and may have a positive impact on the management of patients and their families.

Clinical and genetic features of 64 young male paediatric patients with congenital hypogonadotropic hypogonadism

CONTEXT

The diagnosis of congenital hypogonadotropic hypogonadism (CHH) in prepuberty has always been challenging. Here, we aimed at studying the clinical and genetic features of paediatric CHH, especially the phenotype of hypospadias and dual defects (patients showing hypothalamic and/or pituitary defects and testicular hypoplasia), so as to have a better understanding of CHH.

DESIGN

The clinical and genetic features of patients with CHH were analysed, and the relationships between hypospadias, dual defects and genetics were investigated.

PATIENTS

Patients who visited Beijing Children's Hospital and were positively diagnosed with CHH.

MEASUREMENTS

The collected data included sex hormones, MRI of the olfactory bulb, human chorionic gonadotrophin (hCG) test and genetic testing. We analysed clinical features and genetic results, especially hypospadias and dual defects, and compared the stimulated testosterone (T) levels in patients with and without cryptorchidism.

RESULTS

Sixty-four patients were positively diagnosed, and forty-seven (73.4%) had Kallmann syndrome (KS). Four patients (6.3%) had hypospadias, including 2 KS. Micropenis combined with cryptorchidism was the most common phenotype (39%). Approximately two-third of patients showed a poor response to hCG; 15 cases were diagnosed with dual defects, and there were no significant differences between those with and without cryptorchidism. Twenty-six cases (51%) of 51 patients were identified as having classical HH mutations, affecting 10 different genes, with oligogenic mutations in 5 cases (9.8%). The most common mutations were in PROKR2 (17.6%), FGFR1 (13.7%) and CHD7 (7.8%). The frequency of PROKR2 mutations was higher in dual HH when compared to other HH cases (6/15 vs 3/36, P = .021).

CONCLUSIONS

Micropenis and/or cryptorchidism can serve as important signs for the diagnosis of HH in paediatrics, and the coexistence of hypospadias does not exclude the diagnosis of CHH, including KS or normosmic isolated HH (nHH). Testicular function may be impaired earlier than expected, and PROKR2 mutations need to be evaluated to identify presumed dual defects.

Clinical characteristics of 138 Chinese female patients with idiopathic hypogonadotropic hypogonadism

OBJECTIVE

To evaluate the clinical features of Chinese women with idiopathic hypogonadotropic hypogonadism (IHH).

METHODS

We retrospectively reviewed the clinical characteristics, laboratory and imaging findings, therapeutic management and fertility outcomes of 138 women with IHH. All patients had been treated and followed up at an academic medical centre during 1990-2016.

RESULTS

Among the 138 patients, 82 patients (59.4%) were diagnosed with normosmic IHH and 56 patients (40.6%) were diagnosed with Kallmann syndrome (KS). The patients with IHH experienced occasional menses (4.3%), spontaneous thelarche (45.7%) or spontaneous pubarche (50.7%). Women with thelarche had a higher percentage of pubarche (P  < 0.001) and higher gonadotropin concentrations (P  < 0.01). Olfactory bulb/sulci abnormalities were found during the magnetic resonance imaging (MRI) of all patients with KS. Most patients with IHH had osteopenia and low bone age. Among the 16 women who received gonadotropin-releasing hormone treatment, ovulation induction or assisted reproductive technology, the clinical pregnancy rate was 81.3% and the live birth rate was 68.8%.

CONCLUSIONS

The present study revealed that the phenotypic spectrum of women with IHH is broader than typical primary amenorrhoea with no secondary sexual development, including occasional menses, spontaneous thelarche or pubarche. MRI of the olfactory system can facilitate the diagnosis of KS. Pregnancy can be achieved after receiving appropriate treatment.