Diagnosing and treating anterior pituitary hormone deficiency in pediatric patients.

Hypopituitarism, or the failure to secrete hormones produced by the anterior pituitary (adenohypophysis) and/or to release hormones from the posterior pituitary (neurohypophysis), can be congenital or acquired. When more than one pituitary hormone axis is impaired, the condition is known as combined pituitary hormone deficiency (CPHD). The deficiency may be primarily due to a hypothalamic or to a pituitary disorder, or concomitantly both, and has a negative impact on target organ function. This review focuses on the pathophysiology, diagnosis and management of anterior pituitary hormone deficiency in the pediatric age. Congenital hypopituitarism is generally due to genetic disorders and requires early medical attention. Exposure to toxicants or intrauterine infections should also be considered as potential etiologies. The molecular mechanisms underlying the fetal development of the hypothalamus and the pituitary are well characterized, and variants in the genes involved therein may explain the pathophysiology of congenital hypopituitarism: mutations in the genes expressed in the earliest stages are usually associated with syndromic forms whereas variants in genes involved in later stages of pituitary development result in non-syndromic forms with more specific hormone deficiencies. Tumors or lesions of the (peri)sellar region, cranial radiation therapy, traumatic brain injury and, more rarely, other inflammatory or infectious lesions represent the etiologies of acquired hypopituitarism. Hormone replacement is the general strategy, with critical periods of postnatal life requiring specific attention.

Hemiarhinia caused by a missense variation in SMCHD1: A mild phenotype in the clinical spectrum of Bosma arhinia microphthalmia syndrome.

Bosma arhinia microphthalmia syndrome (BAMS, OMIM #603457) is a rare autosomal dominant disorder caused by heterozygous variation in the SMCHD1 gene on chromosome 18p11. Clinically, it is characterized by microphthalmia, absence or hypoplasia of nose, choanal atresia, anosmia, palatal abnormalities, hypogonadotropic hypogonadism, and cryptorchidism. Here we report a Brazilian patient with a likely pathogenic variation in SMCHD1 gene (c.1418A>T; p.Glu473Val) presenting hemiarhinia associated with short stature and hypogonadotropic hypogonadism. Due to the clinical variability of BAMS, we considered that hemiarhinia, without microphthalmia, in the present case, can be considered a mild form of BAMS and could be considered for screening of SMCHD1 gene variation.

Effect of Combined Low Dose hCG, FSH and Testosterone therapy (LFT Regimen) versus Conventional High Dose hCG and FSH on Spermatogenesis and Biomarkers in Men with Hypogonadotropic Hypogonadism.

OBJECTIVE: In male Congenital hypogonadotropic hypogonadism(CHH), it was observed that lower dose human gonadotropic hormone(hCG) can maintain normal intratesticular testosterone(ITT) levels. We propose this study to compare the Low-Dose hCG, follicle stimulating hormone(FSH), and Testosterone(T) [LFT Regimen] to conventional treatment to induce virilization and fertility. DESIGN: This open-label randomized pilot study was conducted from June 2020 to December 2021. SUBJECTS AND OUTCOME MEASURES: CHH were randomly assigned to either the LFT regimen (Group A)-low-dose hCG (500U thrice per week), FSH(150U thrice per week) and T(100mg biweekly) or conventional therapy(GroupB) with high hCG dose(2000U thrice per week) and the same FSH dose. The hCG dosage was titrated to reduce Anti-mullerian hormone(AMH) by 50% and normalization of plasma T in groups A and B, respectively. The primary objective was to compare the percentage of individuals who achieved spermatogenesis between the two groups. RESULTS: Out of 30 patients, 23(76·7%) subjects achieved spermatogenesis, and the median time was 12(9-14·9)months. There was no difference in achieving spermatogenesis between the two groups (64·3%vs87·5%,p=0·204), and even the median time for spermatogenesis was similar (15monthsvs12months,p=0·248). Both groups had non-significant median plasma AMH at spermatogenesis,[6·6ng/ml(3·3-9·76) vs 4·41ng/ml(2·3-6·47),p=0·298]. Similarly, the median plasma Inhibin B at spermatogenesis between groups were comparable[152·4pg/ml(101·7-198·0)vs149·1pg/ml(128·7-237·3),p=0·488]. CONCLUSIONS: A reasonable approach to induce fertility in male CHH is to initiate combination therapy using FSH, low-dose hCG targeting AMH <6·9 ng/ml, along with T to achieve normal range. Monitoring AMH could serve as a proxy indicator of spermatogenesis.

Fertility outcomes in male adults with congenital hypogonadotropic hypogonadism treated during puberty with human chorionic gonadotropin and recombinant follicle stimulating hormone.

AIM: Hormone replacement therapy with testosterone for pubertal induction in boys with congenital hypogonadotropic hypogonadism (CHH) achieves virilization but not spermatogenesis. By contrast, human chorionic gonadotropin (hCG) and recombinant follicle stimulating hormone (rFSH) provides both virilization and spermatogenesis. Fertility outcomes of boys treated with recombinant therapy during adolescence have been infrequently described. We report fertility induction and pregnancy outcomes in CHH patients treated with recombinant gonadotropins during puberty. METHODS: Data of six subjects with CHH (n = 3 Kallmann syndrome & n = 3 Isolated hypogonadotropic hypogonadism) treated with hCG and FSH for pubertal induction were reviewed. Of these, five underwent subsequent fertility induction while one desired fertility at the end of pubertal induction. RESULTS: Partners of all subjects achieved pregnancies using hCG and rFSH, all with full term live births. All infants were clinically normal. CONCLUSION: This study provides early evidence of proof of concept of use of gonadotropin induction of puberty being beneficial in subsequent fertility outcome.

Prolactin levels in functional hypothalamic amenorrhea: a retrospective case-control study.

PURPOSE: Functional hypothalamic amenorrhea (FHA) is due to hypothalamic dysregulation. Literature lacks data about prolactin in FHA women, although both prolactin levels and FHA are associated with stress. Moreover, polycystic ovarian morphology is common in FHA and there is an association between FHA and polycystic ovary syndrome. Thus, the aim of this study was to assess prolactin levels in FHA patients and controls with a special focus on factors influencing prolactin levels, that could be considered as "sensors" of the hypothalamic-pituitary dysregulation. METHODS: In a retrospective cohort study, 140 women with clearly defined FHA were compared to 70 healthy, normally ovulating women matched for age. The main outcome parameter was prolactin. Factors associated with prolactin levels > 12 µg/L were tested using a multivariable binary logistic regression model. RESULTS: The median prolactin level was 11.5 µg/L (interquartile range, IQR 7.5-14.4), which was similar to the control group (median 10.7, IQR 8.3-14.5; p = 0.065). Only two women had hyperprolactinemia (prolactin > 25 µg/L; 1.4%). In a multivariable binary logistic regression model eating disorder (odds ratio, OR 0.206; p = 0.040), excessive exercise (OR 0.280; p = 0.031) and TSH (OR 1.923; p = 0.020) were significantly associated with prolactin levels > 12 µg/L. CONCLUSION: Women with FHA have similar prolactin levels to healthy age-matched individuals. Eating disorders and excessive exercise where associated with prolactin levels < 12 µg/L, in contrast to TSH.

Impact of Cushing's syndrome on the gonadotrope axis and testicular functions in men.

STUDY QUESTION: Does Cushing's syndrome (CS) differently affect the gonadotrope axis and testicular functions (GA/TF) according to the hypercortisolism intensity and underlying etiology? SUMMARY ANSWER: Endogenous cortisol excess caused by CS leads to varying degrees of hypogonadotropic hypogonadism (HH) with more severe GA/TF impairment and altered spermatogenesis in men with intense hypercortisolism associated with paraneoplastic/ectopic adrenocorticotrophic hormone (ACTH) secretion (EAS). WHAT IS KNOWN ALREADY: CS is very rarely studied in men due to its lower prevalence in men than in women. In a few old reports focusing exclusively on a limited number of men with Cushing's disease (CD), the occurrence of hypogonadism was reported. However, a detailed assessment of the impact of CS on the GA/TF in a significant series of patients has not been performed. Yet, hypogonadism could worsen CS-associated comorbidities such as osteoporosis and myopathy. To date, the full spectrum of GA/TF impairment in men with CS of different etiologies and intensity remains unknown. STUDY DESIGN, SIZE, DURATION: In this monocentric study, 89 men with CS diagnosed at a tertiary endocrine university center (Bicêtre, Paris Saclay) between January 1990 and July 2021 were evaluated and compared to 40 normal men of similar age. PARTICIPANTS/MATERIALS, SETTING, METHODS: The CS patient cohort of 89 men included 51 with CD, 29 with EAS and 9 with CS of adrenal origin i.e. (ACTH-independent CS (AI-CS)). They all had frank hypercortisolism, with increased 24 h-urinary-free cortisol (24 h-UFC) in two separate samples. A case-control study was performed focusing on pituitary gonadotrope function and testicular sex steroids and peptides. An additional set of six CS men had an evaluation including semen analysis. In a subgroup of 20 men with available data after CS remission, a longitudinal analysis was conducted to assess the reversibility of GA/TF defects. MAIN RESULTS AND THE ROLE OF CHANCE: Compared to controls, men with CS had significantly lower total testosterone (TT), bioavailable TT, and free TT (P < 0.0001). Hypogonadism, defined as serum TT levels <3.0 ng/ml, was present in 83% of men with EAS, in 61% of men with CD, and in 33% of men with AI-CS. Low-normal LH concentrations in the included men with hypercortisolism indicated HH. Serum sex hormone-binding globulin levels were moderately decreased in men with CD (P = 0.01 vs controls). Among the CS men, those with EAS had significantly lower TT, LH, and FSH levels than those with CD or AI-CS. When compared to controls, patients with EAS were the only group exhibiting a significant decrease in both serum FSH (P = 0.002) and the testicular peptides inhibin B (P < 0.0001) and anti-Müllerian hormone (P = 0.003). Serum INSL3 levels were significantly lower in men with CD than in the controls (P = 0.03). Of note, 24 h-UFC and ACTH were inversely and significantly associated with the majority of reproductive hormones including LH, FSH, TT, and inhibin B. Following successful curative therapy, reproductive assessment at a mean of 6.0 ± 4.3 years showed a significant increase in serum TT (P < 0.0001) and plasma LH (P = 0.02) levels, indicating a reversal of HH in 75% of the affected males. Among the six patients with available semen analysis, the two EAS cases exhibited a decrease in Sertoli cell peptides associated with a severe oligozoospermia, which completely normalized following removal of the source of hypercortisolism. LIMITATIONS, REASONS FOR CAUTION: The potential bias due to the retrospective design is counteracted by the analysis of the largest male CS cohort to date as well as the use of stringent inclusion and exclusion criteria. Due to the low number of patients with semen analysis in this study, further research is needed to unravel the full spectrum of spermatogenesis defects in men with CS. WIDER IMPLICATIONS OF THE FINDINGS: This work reveals the variable spectrum of reproductive impact in men with CS. We demonstrate that GA/TF impairment depends on the intensity of hypercortisolism which in turn is related to the underlying etiology. The causal link between hypercortisolism and GA/TF impairment was attested by its reversibility in most patients after CS remission. The wider implications of our findings lie in the potential generalization to a much commoner entity, iatrogenic CS due to chronic exposure to exogenous glucocorticoids. STUDY FUNDING/COMPETING INTEREST(S): Several research grants were attributed to J.Y.: (i) a grant from Programme Hospitalier de Recherche Clinique (PHRC # P081212 HYPOPROTEO); (ii) a grant from the French Association of Patients with Adrenal Diseases ('Association surrénales'); and (iii) independent Investigator Research Grants from HRA Pharma, Novartis and Recordati Pharma. A SICPA Foundation grant (Lausanne, Switzerland) allowed protected research time for G.E.P. The above sponsors were not involved in any part of the study. The authors have no competing or other conflicts of interest to declare. TRIAL REGISTRATION NUMBER: N/A.

Stress and polycystic ovarian morphology in functional hypothalamic amenorrhea: a retrospective cohort study.

BACKGROUND: Women with functional hypothalamic amenorrhea (FHA) reveal polycystic ovarian morphology (PCOM) in up to 50%. If stress sensitivity in women with polycystic ovary syndrome (PCOS) is the reason why PCOS women are prone to develop FHA, patients with FHA caused by stress should reveal PCOM more often. METHODS: In a retrospective cohort study, 38 stress-associated and 38 excessive exercise-induced FHA women were included. The main outcome parameter was PCOM. In addition, the focus was on general patient characteristics as well as on prolactin, dehydroepiandrosterone-sulphate (DHEAS), and anti-Mullerian hormone (AMH). RESULTS: PCOM was found in 34/76 patients (44.7%). The stress group showed a higher prevalence of PCOM than the excessive exercise group (57.9% versus 31.6%, p = 0.019) as well as higher prolactin levels (median 13.2ng/mL versus 11.7ng/mL, p = 0.008) and a trend towards higher DHEAS levels (p = 0.058). CONCLUSIONS: In FHA women, the PCOM prevalence was significantly higher in the stress-group than in the excessive exercise-group. The well-known stress sensitivity in women with PCOS might explain why PCOS women are prone to develop FHA as well as the high PCOM prevalence in FHA women.

A de novo hexokinase 1 (HK1) variant presenting as Boucher-Neuhäuser syndrome.

Boucher-Neuhäuser syndrome (BNHS) is characterized by chorioretinal dystrophy, hypogonadotropic hypogonadism, and cerebellar dysfunction and atrophy. The disorder has been associated with biallelic pathogenic variants in the patatin-like phospholipase domain-containing protein 6 (PNPLA6) gene. We present an individual with a clinical diagnosis consistent with BNHS who lacked any PNPLA6 variants but on quartet family exome sequencing had a de novo variant in the hexokinase 1 (HK1) gene (NM_000188.2 [GRCh37/hg19]: g.71139826G>A, c.1240G>A, p.Gly414Arg), suggesting genetic heterogeneity for BNHS. Longitudinal follow-up indicated neurological deterioration, neuropsychiatric symptoms, and progressive cerebellar atrophy. The BNHS phenotype overlaps and expands the known HK1 genotypic and phenotypic spectrum. Individuals with variants in HK1 should undergo evaluation for hypogonadotropic hypogonadism, potentially amenable to treatment.

SIN3A Defects Associated with Syndromic Congenital Hypogonadotropic Hypogonadism: An Overlap with Witteveen-Kolk Syndrome.

INTRODUCTION: Congenital hypogonadotropic hypogonadism (CHH) is a rare condition caused by GnRH deficiency. More than 40 genes have been associated with the pathogenesis of CHH, but most cases still remain without a molecular diagnosis. Mutations involving the same gene (e.g., FGFR1, PROK2/PROKR2, CHD7) were found to cause normosmic CHH and Kallmann syndrome (KS), with and without associated phenotypes, illustrating the coexistence of CHH with signs of other complex syndromes. The Witteveen-Kolk syndrome (WITKOS), caused by defects of the SIN3A gene, is a heterogeneous disorder characterized by distinctive facial features, microcephaly, short stature, delayed cognitive, and motor development. Although micropenis and cryptorchidism have been reported in this syndrome, WITKOS has not been formally associated with CHH so far. PATIENTS AND METHODS: A man with KS associated with mild syndromic features (S1) and a boy with global developmental delay, syndromic short stature, micropenis and cryptorchidism (S2), in whom common genetic defects associated with CHH and short stature had been previously excluded, were studied by either chromosomal microarray analysis or whole exome sequencing. RESULTS: Rare SIN3A pathogenic variants were identified in these 2 unrelated patients with CHH phenotypic features. A 550 kb deletion at 15q24.1, including the whole SIN3A gene, was identified in S1, and a SIN3A nonsense rare variant (p.Arg471*) was detected in S2. CONCLUSION: These findings lead us to propose a link between SIN3A defects and CHH, especially in syndromic cases, based on these 2 patients with overlapping phenotypes of WITKOS and CHH.

Idiopathic hypogonadotropic hypogonadism caused by compound heterozygosity for two novel mutations in the GNRH1 gene: a case report.

BACKGROUND: Idiopathic hypogonadotropic hypogonadism (IHH) is a rare congenital or acquired genetic disorder caused by gonadotropin-releasing hormone (GnRH) deficiency. IHH patients are divided into two major groups, hyposmic or anosmic IHH (Kallmann syndrome) and normosmic IHH (nIHH), according to whether their sense of smell is intact. Here we report a case of novel compound heterozygous mutations in the GNRH1 gene in a 15-year-old male with nIHH. CASE PRESENTATION: The patient presented typical clinical symptoms of delayed testicular development, with testosterone < 3.5 mmol/L and reduced gonadotropin (follicle-stimulating hormone, luteinizing hormone) levels. Two heterozygous variants of the GNRH1 gene were detected, nonsense variant 1: c.85G > T:p.G29* and variant 2: c.1A > G:p.M1V, which disrupted the start codon. CONCLUSIONS: Two GNRH1 mutations responsible for nIHH are identified in this study. Our findings extend the mutational spectrum of GNRH1 by revealing novel causative mutations of nIHH.

Successful pregnancy and delivery after ovulation induction therapy in a woman with congenital hypogonadotropic hypogonadism: a case report.

BACKGROUND: Congenital hypogonadotropic hypogonadism (CHH) is a rare disorder resulting from a deficient secretion of the episodic gonadotropin-releasing hormone, leading to delayed or absent puberty and infertility. In female patients with CHH, the most commonly used treatment is gonadotropin (Gn) therapy. Due to the rarity of the disease in females, there are limited case reports available. This article offers a management approach for this unusual disease that can be helpful for clinicians. CASE PRESENTATION: We report the case of a 29-year-old woman who successfully achieved pregnancy and delivered healthy twin girls after ovulation induction therapy. The patient was diagnosed with CHH at 18 years of age due to primary amenorrhea and the absence of secondary sexual characteristics. After experiencing infertility for three years, the patient sought medical assistance for conceiving. The patient was treated with gonadotropin therapy due to anovulation. In her first treatment cycle, the initial dose of HMG used for treatment was 75IU, which was increased to 150IU after six days. However, the cycle was canceled due to follicular dysplasia. In the second cycle, the treatment began with an initial dose of 150IU, and the follicles grew normally, but the estrogen level was low. Consequently, the treatment was interrupted. In a third ovulation stimulation cycle, HMG was adjusted to 150IU, and recombinant LH was added. After 12 days of ovulation, three mature follicles grew, the estrogen level was normal,and the treatment resulted in successful ovulation and subsequent pregnancy. At 35 weeks of gestation, the patient underwent a cesarean section and delivered two healthy female infants weighing 2,405 g and 2,755 g with an Apgar score of 10/10. CONCLUSIONS: Early diagnosis and timely and appropriate hormone replacement therapy are important for future pregnancy. Ovulation induction therapy is necessary to stimulate fertility. Gn therapy is a feasible and effective treatment for reproduction in CHH females, but the selection of Gn type and dosage must be personalized to maximize fertility outcomes. Effective treatment is available not only for inducing estrogenization and promoting fertility, but also for addressing concerns about psychological and emotional well-being.

ART outcomes of patients in women with Isolated Hypogonadotropic Hypogonadism: a retrospective study in China.

BACKGROUND: Isolated Hypogonadotropic Hypogonadism (IHH) is a rare reproductive disorder caused by the dysfunction of the gonadotropin-releasing hormone axis. Patients with IHH typically fail to enter or develop through puberty and retain infertile without an exogenous hormone supplement. This study aimed to investigate the population characteristics and reproductive outcomes in IHH patients undergoing assisted reproductive technology (ART) treatment, and evaluate the best-performed predictor for ovarian response and clinical pregnancy in patients with IHH. METHODS: This retrospective cohort study included 83 women with IHH who underwent fresh ART cycles and non-diagnosed controls (n = 676). The receiver operating characteristic curves were generated to assess the predictor for the ovarian response. Logistic regression analyses were performed to investigate the independent factors for clinical pregnancy in IHH. RESULTS: The basal hormone levels were significantly lower in the IHH group compared to the control group. The fertilization rate and 2PN rate were significantly higher in IHH groups, as was the number of transferable embryos. The study identified that AMH was the best predictor of high ovarian response in IHH, with an AUC of 0.767 (0.573, 0.961). Conversely, the follicle-to-oocyte index (FOI) exhibited the highest AUC of 0.814 (0.642, 0.985) for predicting low ovarian response. Based on FOI values, the IHH patients were divided into two groups, and the study found a significant increase in clinical pregnancy rate (43.8%, 58%; P < 0.001) and live birth rate (37.5%, 58%; P < 0.001) from the low FOI to the normal FOI groups. Moreover, the number of oocytes retrieved, fertilized embryos/rate, 2PN embryos/rate, and number of excellent quality embryos were significantly higher in the normal FOI group (P < 0.001 or P = 0.005) than in the low FOI group. Logistic regression analyses revealed FOI to be the independent factor affecting clinical pregnancy in IHH patients. CONCLUSIONS: The study findings suggest that patients with IHH were good responders to IVF treatment. Although AMH was the best-performed predictor for the high ovarian response, FOI had the best capability in predicting the low ovarian response. FOI was an independent factor affecting clinical pregnancy in IHH undergoing IVF/ICSI.

Pituitary imaging findings in pediatric patients with idiopathic hypogonadotropic hypogonadism.

Objective. Idiopathic hypogonadotropic hypogonadism in children is a disease leading to a puberty absence. Some hypothalamic and pituitary defects cause hypogonadotropic hypogonadism. Pituitary magnetic resonance imaging is routinely performed in these patients. In our study, we provide an information about pituitary pathologies associated with an idiopathic hypogonado-tropic hypogonadism in childhood. Methods. Twenty-two patients, who were admitted to the pediatric endocrine outpatient clinic of our hospital because of their undeveloped secondary sex characteristics during adolescence, were included in our study. Age, gender, history, physical examination findings, and laboratory tests were recorded in patients. Pituitary magnetic resonance imaging results were examined. The criteria for the diagnosis of hypogonadism were: absence of puberty or delayed puberty, clinical signs or symptoms of hypogonadism, and presence of low or normal gonadotropin levels. Results. In the present study, 22 patients were diagnosed with hypogonadotropic hypogonadism. The mean age of the patients was 15.90±1.09 years. Basal and stimulated luteinizing hormone and follicular stimulating hormone levels of the patients were found to be low. Prolactin, cortisol, adrenocorticotropic hormone, free thyroxine, and thyroid stimulating hormone levels were within normal limits in all patients. The pituitary magnetic resonance imaging revealed six patients with pituitary adenoma, one with empty sella turcica, and five with pituitary hypoplasia. Conclusions. The present data showed that in the presence of hypogonadotropic hypogonadism, the hypothalamic-pituitary abnormalities are more likely to be present in the children compared to the adult population. Thus, it can be strongly emphasized the importance of the pituitary imaging examination, especially in the idiopathic hypogonadotropic hypogonadism cases.

Sex difference in developmental changes in visualized Kiss1 neurons in newly generated Kiss1-Cre rats.

Hypothalamic kisspeptin neurons are master regulators of mammalian reproduction via direct stimulation of gonadotropin-releasing hormone and consequent gonadotropin release. Here, we generated novel Kiss1 (kisspeptin gene)-Cre rats and investigated the developmental changes and sex differences in visualized Kiss1 neurons of Kiss1-Cre-activated tdTomato reporter rats. First, we validated Kiss1-Cre rats by generating Kiss1-expressing cell-specific Kiss1 knockout (Kiss1-KpKO) rats, which were obtained by crossing the current Kiss1-Cre rats with Kiss1-floxed rats. The resulting male Kiss1-KpKO rats lacked Kiss1 expression in the brain and exhibited hypogonadotropic hypogonadism, similar to the hypogonadal phenotype of global Kiss1 KO rats. Histological analysis of Kiss1 neurons in Kiss1-Cre-activated tdTomato reporter rats revealed that tdTomato signals in the anteroventral periventricular nucleus (AVPV) and arcuate nucleus (ARC) were not affected by estrogen, and that tdTomato signals in the ARC, AVPV, and medial amygdala (MeA) were sexually dimorphic. Notably, neonatal AVPV tdTomato signals were detected only in males, but a larger number of tdTomato-expressing cells were detected in the AVPV and ARC, and a smaller number of cells in the MeA was detected in females than in males at postpuberty. These findings suggest that Kiss1-visualized rats can be used to examine the effect of estrogen feedback mechanisms on Kiss1 expression in the AVPV and ARC. Moreover, the Kiss1-Cre and Kiss1-visualized rats could be valuable tools for further detailed analyses of sexual differentiation in the brain and the physiological role of kisspeptin neurons across the brain in rats.

Gonadotropin-Releasing Hormone Receptor (GnRHR) and Hypogonadotropic Hypogonadism.

Human sexual and reproductive development is regulated by the hypothalamic-pituitary-gonadal (HPG) axis, which is primarily controlled by the gonadotropin-releasing hormone (GnRH) acting on its receptor (GnRHR). Dysregulation of the axis leads to conditions such as congenital hypogonadotropic hypogonadism (CHH) and delayed puberty. The pathophysiology of GnRHR makes it a potential target for treatments in several reproductive diseases and in congenital adrenal hyperplasia. GnRHR belongs to the G protein-coupled receptor family and its GnRH ligand, when bound, activates several complex and tissue-specific signaling pathways. In the pituitary gonadotrope cells, it triggers the G protein subunit dissociation and initiates a cascade of events that lead to the production and secretion of the luteinizing hormone (LH) and follicle-stimulating hormone (FSH) accompanied with the phospholipase C, inositol phosphate production, and protein kinase C activation. Pharmacologically, GnRHR can be modulated by synthetic analogues. Such analogues include the agonists, antagonists, and the pharmacoperones. The agonists stimulate the gonadotropin release and lead to receptor desensitization with prolonged use while the antagonists directly block the GnRHR and rapidly reduce the sex hormone production. Pharmacoperones include the most recent GnRHR therapeutic approaches that directly correct the misfolded GnRHRs, which are caused by genetic mutations and hold serious promise for CHH treatment. Understanding of the GnRHR's genomic and protein structure is crucial for the most appropriate assessing of the mutation impact. Such mutations in the GNRHR are linked to normosmic hypogonadotropic hypogonadism and lead to various clinical symptoms, including delayed puberty, infertility, and impaired sexual development. These mutations vary regarding their mode of inheritance and can be found in the homozygous, compound heterozygous, or in the digenic state. GnRHR expression extends beyond the pituitary gland, and is found in reproductive tissues such as ovaries, uterus, and prostate and non-reproductive tissues such as heart, muscles, liver and melanoma cells. This comprehensive review explores GnRHR's multifaceted role in human reproduction and its clinical implications for reproductive disorders.

Genetic Analysis of Patients with Congenital Hypogonadotropic Hypogonadism: A Case Series.

Congenital hypogonadotropic hypogonadism (cHH)/Kallmann syndrome (KS) is a rare genetic disorder with variable penetrance and a complex inheritance pattern. Consequently, it does not always follow Mendelian laws. More recently, digenic and oligogenic transmission has been recognized in 1.5-15% of cases. We report the results of a clinical and genetic investigation of five unrelated patients with cHH/KS analyzed using a customized gene panel. Patients were diagnosed according to the clinical, hormonal, and radiological criteria of the European Consensus Statement. DNA was analyzed using next-generation sequencing with a customized panel that included 31 genes. When available, first-degree relatives of the probands were also analyzed to assess genotype-phenotype segregation. The consequences of the identified variants on gene function were evaluated by analyzing the conservation of amino acids across species and by using molecular modeling. We found one new pathogenic variant of the CHD7 gene (c.576T>A, p.Tyr1928) and three new variants of unknown significance (VUSs) in IL17RD (c.960G>A, p.Met320Ile), FGF17 (c.208G>A, p.Gly70Arg), and DUSP6 (c.434T>G, p.Leu145Arg). All were present in the heterozygous state. Previously reported heterozygous variants were also found in the PROK2 (c.163del, p.Ile55*), CHD7 (c.c.2750C>T, p.Thr917Met and c.7891C>T, p.Arg2631*), FLRT3 (c.1106C>T, p.Ala369Val), and CCDC103 (c.461A>C, p.His154Pro) genes. Molecular modeling, molecular dynamics, and conservation analyses were performed on three out of the nine variants identified in our patients, namely, FGF17 (p.Gly70Arg), DUSP6 (p.Leu145Arg), and CHD7 p.(Thr917Met). Except for DUSP6, where the L145R variant was shown to disrupt the interaction between ß6 and ß3, needed for extracellular signal-regulated kinase 2 (ERK2) binding and recognition, no significant changes were identified between the wild-types and mutants of the other proteins. We found a new pathogenic variant of the CHD7 gene. The molecular modeling results suggest that the VUS of the DUSP6 (c.434T>G, p.Leu145Arg) gene may play a role in the pathogenesis of cHH. However, our analysis indicates that it is unlikely that the VUSs for the IL17RD (c.960G>A, p.Met320Ile) and FGF17 (c.208G>A, p.Gly70Arg) genes are involved in the pathogenesis of cHH. Functional studies are needed to confirm this hypothesis.

Insulin-like Growth Factor 1, Growth Hormone, and Anti-Müllerian Hormone Receptors Are Differentially Expressed during GnRH Neuron Development.

Gonadotropin-releasing hormone (GnRH) neurons are key neuroendocrine cells in the brain as they control reproduction by regulating hypothalamic-pituitary-gonadal axis function. In this context, anti-Müllerian hormone (AMH), growth hormone (GH), and insulin-like growth factor 1 (IGF1) were shown to improve GnRH neuron migration and function in vitro. Whether AMH, GH, and IGF1 signaling pathways participate in the development and function of GnRH neurons in vivo is, however, currently still unknown. To assess the role of AMH, GH, and IGF1 systems in the development of GnRH neuron, we evaluated the expression of AMH receptors (AMHR2), GH (GHR), and IGF1 (IGF1R) on sections of ex vivo mice at different development stages. The expression of AMHR2, GHR, and IGF1R was assessed by immunofluorescence using established protocols and commercial antibodies. The head sections of mice were analyzed at E12.5, E14.5, and E18.5. In particular, at E12.5, we focused on the neurogenic epithelium of the vomeronasal organ (VNO), where GnRH neurons, migratory mass cells, and the pioneering vomeronasal axon give rise. At E14.5, we focused on the VNO and nasal forebrain junction (NFJ), the two regions where GnRH neurons originate and migrate to the hypothalamus, respectively. At E18.5, the median eminence, which is the hypothalamic area where GnRH is released, was analyzed. At E12.5, double staining for the neuronal marker ß-tubulin III and AMHR2, GHR, or IGF1R revealed a signal in the neurogenic niches of the olfactory and VNO during early embryo development. Furthermore, IGF1R and GHR were expressed by VNO-emerging GnRH neurons. At E14.5, a similar expression pattern was found for the neuronal marker ß-tubulin III, while the expression of IGF1R and GHR began to decline, as also observed at E18.5. Of note, hypothalamic GnRH neurons labeled for PLXND1 tested positive for AMHR2 expression. Ex vivo experiments on mouse sections revealed differential protein expression patterns for AMHR2, GHR, and IGF1R at any time point in development between neurogenic areas and hypothalamic compartments. These findings suggest a differential functional role of related systems in the development of GnRH neurons.

Cases of hypogonadotropic hypogonadism: A single-center experience.

Background: Delayed puberty (DP) affects approximately 2% of adolescents. In most patients of both genders, delayed puberty is due to constitutional delay in growth and puberty (CDGP); it is a self-limiting condition starting later than usual during puberty but progressing normally. Other causes of DP include permanent hypogonadotropic hypogonadism, functional hypogonadotropic hypogonadism, and gonadal insufficiency. Methods: Nine patients admitted to the Ankara Atatürk Sanatoryum Training and Research Hospital Pediatric Endocrinology Department with hypogonadotropic hypogonadism between January 2012 and December 2022 were analyzed. Results: Nine patients who applied to our pediatric endocrinology clinic with delayed puberty were analyzed. These nine patients were diagnosed and reported as hypogonadotropic hypogonadism with molecular methods. We aimed to determine the status of these cases from a molecular point of view, to emphasize the importance of hypogonadotropic hypogonadism in patients with delayed puberty, and to reveal the rarely encountered delayed puberty together with the clinical and laboratory data set of the patients. Conclusions: To emphasize the importance of hypogonadotropic hypogonadism, which is a rare cause of delayed puberty, the molecular predispositions of our patients followed in our clinic are reviewed, and the data we have provided will contribute to the accumulation of data in this area.

PLXNA1 and PLXNA3 cooperate to pattern the nasal axons that guide gonadotropin-releasing hormone neurons.

Gonadotropin-releasing hormone (GnRH) neurons regulate puberty onset and sexual reproduction by secreting GnRH to activate and maintain the hypothalamic-pituitary-gonadal axis. During embryonic development, GnRH neurons migrate along olfactory and vomeronasal axons through the nose into the brain, where they project to the median eminence to release GnRH. The secreted glycoprotein SEMA3A binds its receptors neuropilin (NRP) 1 or NRP2 to position these axons for correct GnRH neuron migration, with an additional role for the NRP co-receptor PLXNA1. Accordingly, mutations in SEMA3A, NRP1, NRP2 and PLXNA1 have been linked to defective GnRH neuron development in mice and inherited GnRH deficiency in humans. Here, we show that only the combined loss of PLXNA1 and PLXNA3 phenocopied the full spectrum of nasal axon and GnRH neuron defects of SEMA3A knockout mice. Together with Plxna1, the human orthologue of Plxna3 should therefore be investigated as a candidate gene for inherited GnRH deficiency.

The p190 RhoGAPs, ARHGAP35, and ARHGAP5 are implicated in GnRH neuronal development: Evidence from patients with idiopathic hypogonadotropic hypogonadism, zebrafish, and in vitro GAP activity assay.

PURPOSE: The study aimed to identify novel genes for idiopathic hypogonadotropic hypogonadism (IHH). METHODS: A cohort of 1387 probands with IHH underwent exome sequencing and de novo, familial, and cohort-wide investigations. Functional studies were performed on 2 p190 Rho GTPase-activating proteins (p190 RhoGAP), ARHGAP35 and ARHGAP5, which involved in vivo modeling in larval zebrafish and an in vitro p190A-GAP activity assay. RESULTS: Rare protein-truncating variants (PTVs; n = 5) and missense variants in the RhoGAP domain (n = 7) in ARHGAP35 were identified in IHH cases (rare variant enrichment: PTV [unadjusted P = 3.1E-06] and missense [adjusted P = 4.9E-03] vs controls). Zebrafish modeling using gnrh3:egfp phenotype assessment showed that mutant larvae with deficient arhgap35a, the predominant ARHGAP35 paralog in the zebrafish brain, display decreased GnRH3-GFP+ neuronal area, a readout for IHH. In vitro GAP activity studies showed that 1 rare missense variant [ARHGAP35 p.(Arg1284Trp)] had decreased GAP activity. Rare PTVs (n = 2) also were discovered in ARHGAP5, a paralog of ARHGAP35; however, arhgap5 zebrafish mutants did not display significant GnRH3-GFP+ abnormalities. CONCLUSION: This study identified ARHGAP35 as a new autosomal dominant genetic driver for IHH and ARHGAP5 as a candidate gene for IHH. These observations suggest a novel role for the p190 RhoGAP proteins in GnRH neuronal development and integrity.