Normosmic Congenital Hypogonadotropic Hypogonadism Research Articles

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.

The diagnostic value of the olfactory evaluation for congenital hypogonadotropic hypogonadism

ObjectiveThe aim of this study was to evaluate the diagnostic accuracy of different olfactory evaluation tools in congenital hypogonadotropic hypogonadism (CHH) patients.MethodsSeventy-one CHH patients were prospectively recruited at Peking Union Medical College Hospital between November 2020 and July 2021. The Chinese Olfactory Function Test (COFT) and Self-reported Olfactory Scale (SROS) were adapted as the subjective tools for the evaluation of olfactory function, and magnetic resonance imaging of olfactory apparatus (MRI-OA) was the objective tool. The olfactory bulb volume (OBV) and the olfactory sulcus depth (OSD) were quantified.ResultsBased on the COFT, 36 patients were categorized as having normosmic CHH (nCHH), and the other 35 patients were categorized as having Kallmann syndrome (KS). Among nCHH patients, 35 patients were classified as having normal olfaction and 1 patient had abnormal olfaction by SROS. For KS patients, there were 30 patients grouped into abnormal olfaction, while 5 patients had normal olfaction by SROS. For MRI-OA, 67% (18/27) of nCHH patients showed normal olfactory apparatus, and 33% (9/27) showed bilateral or unilateral olfactory bulb aplasia or hypoplasia. Among KS patients, 96% (27/28) of patients showed bilateral olfactory bulb hypoplasia or aplasia, and 4% (1/28) of patients showed normal olfactory apparatus. All six patients with unilateral olfactory bulb aplasia and three patients with bilateral olfactory bulb aplasia showed normal olfactory function. The accuracy of the SROS in the diagnosis of nCHH and KS was 91.5%, with a sensitivity of 0.857 and a specificity of 0.972, while the accuracy of MRI-OA is 92.7%, with a sensitivity of 0.964 and a specificity of 0.889.ConclusionSROS and MRI-OA both showed high accuracy to distinguish between KS and nCHH. The abnormal structure of the olfactory apparatus was relatively common in nCHH patients. CHH patients with unilateral olfactory bulb aplasia dysplasia usually had normal olfaction. Normal olfaction without apparent olfactory bulbs is rare but occurred in male CHH patients.

Regional genotypic variations in normosmic congenital hypogonadotropic hypogonadism: our experience and systematic review

To describe phenotype-genotype data of Asian-Indian normosmic congenital hypogonadotropic hypogonadism (nCHH) from our centre and perform a systematic review of genetic studies using next-generation sequencing (NGS) in nCHH. Sixty-eight nCHH probands from our center, and 370 nCHH probands from published studies were included. Per-patient genetic variants were analyzed as per ACMG guidelines. Molecular diagnosis was defined as presence of a pathogenic or likely pathogenic variant in a known CHH gene following zygosity status as per known mode of genetic inheritance. At our centre molecular diagnosis was observed in 35.3% of probands {GNRHR:16.2%, FGFR1:7.3%, KISS1R:4.4%, GNRH1:2.9%, TACR3:2.9%, CHD7:1.4%}. Molecular diagnosis was observed more often (44.7% vs 14.3%, p = 0.026) with severe than partial reproductive-phenotype. The study adds 12 novel variants and suggests GNRHR p.Thr32Ala variant may have a founder effect. In per-patient systematic review (including our cohort), the molecular diagnosis was reached in 23.2%, ranging from 3.5 to 46.7% at different centers. The affected genes were FGFR1:6.4%, GNRHR:4.3%, PROKR2:3.6%, TACR3:1.8%, CHD7:1.6%, KISS1R:1.4%, GNRH1:1.4% and others (PROK2, SOX3, SOX10, SOX11, IL17RD, IGSF10, TAC3, ANOS1, oligogenic): < 1% each. FGFR1 was the most commonly affected gene in most cohorts except Asia, whereas PROKR2 (in China and Japan) and GNRHR (in India) were the commonest. (s): The global molecular diagnosis rate was 23.2% in nCHH cohorts whereas that in our cohort was 35% with a higher rate (44.7%) in those with severe reproductive-phenotype. The most commonly affected gene in nCHH patients was FGFR1 globally while it was PROKR2 in East Asia and GNRHR in India.

Genetic Profiles and Three-year Follow-up Study of Chinese Males With Congenital Hypogonadotropic Hypogonadism

BackgroundThe correlation between long-term treatment outcomes with genotypes in congenital hypogonadotropic hypogonadism (CHH) males is rarely reported. AimTo investigate the correlations among genotypes, phenotypes, and treatment outcomes for CHH male patients. MethodsWhole exome sequencing was performed for 73 Chinese CHH males from one academic center. Patients self-selected one of the 4 treatments: pulsatile Gonadorelin pump (PGP), cyclical gonadotropins therapy (CGT), human menopausal gonadotropin monotherapy, or testosterone replacement treatment. Clinical assessments were performed every 3 months for 3 years. OutcomesThe pathogenicity of variants was determined. Baseline clinical features, spermatogenesis outcomes were analysed. Results62 variants were identified in 51 patients (69.9%), 17 of which were novel. Among these mutations, variants on FGFR1, PROKR2, CHD7, ANOS1 and NSMF gene were 16.1%, 16.1%, 11.3%, 8.1% and 8.1% respectively. 11 patients followed the oligogenic pattern (21.6%). All CHD7 patients had hearing impairment or structural deformities of external/inner ear, and were diagnosed as CHARGE syndrome. 24.7% of CHH patients manifested with ear/hearing anomalies. KS patients had higher rates of cryptorchidism history and ear/hearing anomalies than normosmic CHH subjects. Male patients with PROKR2 mutations showed relatively better testicular development, less dental deformity when compared with FGFR1 mutations. About 30% normosmic patients defined by simple olfactory assessment showed olfactory nerve center (ONC) dysplasia under nasal sinus MRI examination. Among the CHH males treated with CGT or PGP, 70.2% reached spermatogenesis within 3 years of treatment. Clinical ImplicationsNo direct correlation was observed between certain responsible genes and spermatogenic outcomes. When CHH patients were identified with CHD7 variants, ear/hearing evaluation should be carefully performed. The precise assessment of ONC development was advised for normosmic CHH subjects. Strengths & LimitationsThis study provided informative long-term treatment data of CHH male patients screened with whole exome sequencing. The limitations included small number of subgroups with multifaceted gene variants, clinical heterogeneity, and uncontrolled sperm-inducing treatment method. The seventeen novel mutations worth experimental validation in the future. ConclusionThe clinical severity is partially related with specific gene variants, and detailed individualized data and outcomes were provided. Ear/hearing anomalies were closely connected with CHD7 variants, and were common problems for CHH patients. Simple olfactory assessment underestimated the true olfactory deficit. L. Zhang, Y. Gao, Q. Du, et al. Genetic Profiles and Three-year Follow-up Study of Chinese Males With Congenital Hypogonadotropic Hypogonadism. J Sex Med 2021;18:1500–1510.

SUN-032 Digenic Inheritance of PCSK1 and CHD7 Mutations in PAX4 Homozygous Diabetic Male with Normosmic Hypogonadotropic Hypogonadism

Background: Normosmic congenital hypogonadotropic hypogonadism denotes Kallmann syndrome not associated with anosmia or hyposmia. Over the past few years, the availability of next-generation sequencing has started to unravel the complex molecular basis of congenital hypogonadotrophic hypogonadism including digenic or oligogenic pathogenecity in addition to classic monogenic causality (1). Clinical Case: A 22-year-old male patient was referred to the endocrine clinic in 2018 with recent -onset hyperglycemia. His weight was 82.2 kg with a height of 180 cm (BMI of 25.3 kg/m2). Physical examination revealed small testes, micropenis, and no axillary and pubic terminal hair. His smell sense was intact. His hormonal test reveals low testosterone (0.10 ng/mL) and low free testosterone (0.65 pg/mL) levels with inappropriately low gonadotrophins levels. Secretion of LH and FSH increased 2-fold after GnRH stimulation. His bone age was 13-years 6-months old, and brain magnetic resonance imaging showed the presence of olfactory bulbs, and unremarkable findings except for small size of the pituitary gland. There were no signs associated with CHARGE syndrome (coloboma ocular, heart defects, atresia or stenosis of the choanae, retardation of growth and/or development, genitourinary anomalies, and ear abnormalities). Biochemical investigation demonstrated high serum glucose level and high HbA1c (13.8%). To identify variants to cause the phenotype of the proband, we adopted trio-based whole exome sequencing (WES) and candidate gene approach. Candidate genes was listed from the orphanet (https://www.orpha.net). WES of the proband revealed the presence of heterozygote missense mutations of the CHD7 gene (c.6107C>T, p.Pro2036Leu, rs369543203) and PCSK1 gene (c.239G>A, p.Arg80Gln, rs1799904). The missense variants were predicted to have a damaging effect on the encoded protein, by SIFT and PolyPhen-2 analyses. Genetic analyses of his family revealed that his father had the same heterozygote missense mutations of the CHD7 gene, but wild type of PCSK1. Proband’s mother had the same heterozygote missense mutations of PCSK1, but wild type of CHD7. Furthermore, the proband had homozygote missense mutation of PAX4 (c.575G>A, p.Arg192His, rs2233580) known as maturity-onset diabetes of the young (MODY) 9 gene. Both parents have the same but heterozygous mutation of PAX4 p.Arg192His, and pre-diabetic range of hyperglycemia. Conclusion: This is the first case demonstrating digenic inheritance of mutations in PCSK1 and CHD7 as a potential cause of normosmic hypogonadotrophic hypogonadism, interestingly in PAX4 homozygous diabetic male. Reference: (1) Maione L, et al. Genetic counseling for congenital hypogonadotropic hypogonadism and Kallmann syndrome: new challenges in the era of oligogenism and next-generation sequencing. Eur J Endocrinol. 2018;178(3):R55-R80.

A single-nucleotide polymorphism induced alternative splicing in Tacr3 involves in hypoxic-ischemic brain damage

Single-nucleotide polymorphism (SNP) and Alternative splicing (AS) were found to be implicated in certain diseases, nevertheless, the contributions of mRNA SNPs and AS to pathogenesis in developing rat brains with hypoxic-ischemic encephalopathy (HIE) remained largely vague. Additionally, the disease associated with Tacr3 was normosmic congenital hypogonadotropic hypogonadism, while the relationship between HIE and Tacr3 remained largely elusive. The current study was designed to investigate the differentially expressed mRNAs and related SNPs as well as AS in neonatal rats subjected to HIE to identify if the exhibition of AS was associated with SNPs under pathological condition. Firstly, we used postnatal day 7 Sprague-Dawley rats to construct neonatal HIE model, and analyzed the expression profiles of SNP mRNA in hypoxic-ischemic (HI) and sham brains by using RNA sequencing. Then four genes, including Mdfic, Lpp, Bag3 and Tacr3, connecting with HIE and exhibiting SNPs and AS were identified by bioinformatics analysis. Moreover, combined with exonic splicing enhancer (ESE) and alternative splice site predictor (ASSP) analysis, we found that Tacr3 is associated specifically with HIE through 258547789 G > A SNP in inside the Alt First Exon and 258548573 G > A SNP in outside the Alt First Exon. Taken together, our study provides new evidence to understand the role of Tacr3 in HIE and it is possibly a potential target for the treatment of HIE in future clinic trial.

Nonstop mutation in the Kisspeptin 1 receptor (KISS1R) gene causes normosmic congenital hypogonadotropic hypogonadism.

Congenital hypogonadotropic hypogonadism (CHH) is a rare genetic disorder mostly characterized by gonadotropins release and/or action deficiencies. Both isolated (idiopathic hypogonadotropic hypogonadism) and syndromic (Kallmann) forms are identified depending on the olfactory ability. Clinical and genetic heterogeneities of CHH have been widely explored, thus improving our understanding of the disease's pathophysiology. This work aims to (1) provide a detailed clinical and hormonal description of normosmic CHH patients and (2) identify the mutation linked to the studied phenotype. We investigated three affected patients with normosmic CHH, belonging to a consanguineous Tunisian family. Patients underwent an insulin-induced hypoglycemia test. We performed whole exome sequencing to identify the causal mutation. At first diagnosis, a total gonadotropic deficiency was identified in all patients. The insulin-induced hypoglycemia test has also revealed a reduced cortisol secretion and complete growth hormone deficiency. At 20.8years, one female exhibited a spontaneous recovery of the hypothalamic-pituitary-adrenal axis function, unlike her affected siblings who still depend on corticosteroid replacement therapy. Herein, we identified a novel homozygous nonstop mutation (c.1195T>C) in KISS1R gene in all affected subjects. This mutation led to the substitution of the physiologic stop codon by an arginine (p.X399R). Our study highlights the importance of the KISS1R signaling, in gonadotropin-releasing hormone neurons, in the control of reproductive function. Additionally, our data suggests a complex central and peripheral metabolic control of puberty, through the hypothalamic KISS1R signaling. We suggest a mutual link between the hypothalamic-pituitary-gonadal, -adrenal, and -somatotropic axes.

A novel rare case of normosmic congenital hypogonadotropic hypogonadism associating a GnRHR and a KISS1R variants

A novel rare case of normosmic congenital hypogonadotropic hypogonadism associating a GnRHR and a KISS1R variants

MON-244 GnRH Test Does Not Efficiently Discriminate Congenital Isolated Hypogonadotropic Hypogonadism from Constitutional Delay of Growth and Puberty in Males

Context: Delayed puberty can be due to either constitutional delay of growth and puberty (CDGP) or congenital hypogonadotropic hypogonadism (CHH). Differentiating between the two conditions either clinically or using current hormonal testing is difficult. GnRH test is currently used in many centers to differentiate CDGP from CHH but its diagnostic performance was not assessed in a significant number of CHH patients. Objective: To compare gonadotropin responses to GnRH challenge between CHH and C and to assess the diagnostic performance of this test in large cohorts of CHH and CDGP. Subjects: We included 127 men with CHH (68 Kallmann Syndrome (KS) and 69 normosmic CHH; age: 25.5±9.9 y), 74 men with CDGP (14.9±1.0 y) not treated, 31 control (C) men (25.9±5.2 y). Methods: Testicular volume (TV) was measured. Basal testosterone and inhibin B (IB, limit of detection: 3 pg/mL) were measured using sensitive immunoassays. Intravenous injection of 100 μg GnRH was performed. Serum FSH and LH were measured (at -15, 0, 15, 30, 60, and 120 min) using sensitive immunoradiometric assays with a detection limit of 0.05 IU/L for both gonadotropins. Results (mean±SD, [range]): Testosterone levels (ng/mL) were: C, 6.5±1.2 [4.2-8.7]; CHH/KS, 0.5±0.4 [0.0-2.1]; CDGP, 0.6±0.6 [0.0-2.5]. Testicular volumes (mL) were respectively in CHH/KS and CDGP: 3.1±2.8 [0.1-13.5] and 4.5±2.7 [0.7-10]. LH basal and peaks (IU/L) were: C, basal: 4.2±0.9 [2.9-6.1], peak 17.9±3.7 [11.1-26.0]; CHH/KS, basal 0.8±1.0 [0.1-4.2], peak: 6.9±7.8 [0.1-41.5]; CDGP, basal: 1.3±0.8 [0.1-3.7]; peak: 13.9±6.3 [4.0-33.4]. In 25/127 (21%) of CHH/KS, we found an overlapping in serum LH peaks levels when compared to C. Importantly, in 47% (60/127) of CHH/KS patients, GnRH-induced LH peaks overlapped with LH peak values observed in CDGP. However, none of the patients with CDGP had LH peak values below 4.0 IU/L while 68/127 (53%) of those with CHH/KS had LH peak levels below this threshold. In CHH/KS and CDGP, serum IB were respectively (58±64 [3-311] and 164±97 [35-630]). In 59% of untreated CHH/KS patients, serum IB overlapped with CDGP. In CHH, we found a significant positive correlation between LH peak and TV (r=0.41; p < 0.0001) and a stronger positive correlation between LH peak and IB (r=0.49; p< 0.0001). Conclusion: In both CHH/KS and CDGP, the ranges of GnRH induced LH peaks were very wide and a strong overlapping was found between the three groups studied. Both LH peak and IB were correlated with the severity of gonadotropin deficiency as reflected by TV. The GnRH challenge test is not efficient enough to discriminate CHH/KS from CDGP but very weak LH responses (4 IU/L) were specifically observed in CHH/KS. Diagnosis efficiency of serum IB will also be discussed.

Whole Exome Sequencing Revealed a Novel Nonsense Variant in the GNRHR Gene Causing Normosmic Hypogonadotropic Hypogonadism in a Pakistani Family

Background: Congenital hypogonadotropic hypogonadism (CHH) is a heterogeneous disorder characterized by delayed or loss of puberty and infertility due to functional deficiency in the hypothalamic gonadotropin-releasing hormone (GnRH). CHH can be classified into 2 subtypes on the basis of olfaction: Kallmann syndrome and normosmic CHH (nCHH). The spectrum of genetic variants causing CHH is continually expanding. Here, we recruited a consanguineous Pakistani family having 2 male and 2 female infertile patients diagnosed with idiopathic nCHH. Aims: The aim of this study was to investigate the genetic cause of nCHH in the family. Methods: Clinical and physical analyses were performed for the patients. Genetic analysis was carried out using whole exome and Sanger sequencing. Results: Clinical and physical investigations confirmed low levels of gonadotropins and failure of secondary sexual development in the patients. Genetic analysis identified a novel nonsense mutation (chr4: g.68619942G>A, c.112C>T, p.Arg38*) in the gonadotropin-releasing hormone receptor gene (GNRHR) recessively co-segregating with nCHH in this family. All the patients are homozygous and their parents are heterozygous carriers, while normal siblings are heterozygous carriers or wild-type for this mutation, indicating that the identified mutation is pathogenic for nCHH in the family. Conclusion: We report the first homozygous nonsense mutation in the GNRHR gene (chr4: g. 68619942G>A, c.112C>T, p. Arg38*) that is associated with familial nCHH. Hence, our study displayed a good correlation of the genotype and phenotype of nCHH patients.

Conformational Change in the Ligand-Binding Pocket via a KISS1R Mutation (P147L) Leads to Isolated Gonadotropin-Releasing Hormone Deficiency.

Context:Kisspeptin receptor (KISS1R) is expressed in hypothalamic gonadotropin-releasing hormone neurons and responsible for pubertal onset and reproductive functions. KISS1R mutations remain a rare cause of congenital hypogonadotropic hypogonadism (CHH).Objective:The aim of this study was to identify the genetic cause of CHH in a patient and to functionally characterize a KISS1R mutation.Design:The patient was a 47-year-old Japanese man whose parents were first cousins. He lacked secondary sexual characteristics owing to normosmic CHH. Exon segments for the KISS1R gene in this patient were screened for mutations. Functional analyses were performed using HEK293 cells expressing KISS1R mutants. Molecular dynamics simulations were performed to compare the ligand-KISS1R mutant complex with those of wild-type KISS1R variants.Results:A homozygous mutation (c.440C>T, p.P147L) in KISS1R was identified. The P147L mutation did not affect either receptor expression level or subcellular localization in the recombinant expression system. Intracellular calcium measurements and cellular dielectric spectroscopy demonstrated that the P147L mutation impaired receptor function to an extent more severe than that of a previously reported L148S mutation. A receptor-ligand binding assay showed the P147L mutation causes a substantial loss of ligand-binding affinity. Molecular dynamics simulations revealed the P147L mutation decreases the contact surface area of the ligand-receptor complex in an expanded ligand-binding pocket.Conclusion:We identified a loss-of-function mutation in KISS1R associated with CHH. Our results demonstrated that the P147L mutation causes a severe phenotype and functional impairment resulting from the loss of ligand-binding affinity due to an expanded ligand-binding pocket.

GNRHR biallelic and digenic mutations in patients with normosmic congenital hypogonadotropic hypogonadism.

ObjectiveNormosmic congenital hypogonadotropic hypogonadism (nCHH) is a rare disorder characterised by lack of pubertal development and infertility, due to deficient production, secretion or action of gonadotropin-releasing hormone (GnRH) and, unlike Kallmann syndrome, is associated with a normal sense of smell. Mutations in the GNRHR gene cause autosomal recessive nCHH. The aim of this study was to determine the prevalence of GNRHR mutations in a group of 40 patients with nCHH.DesignCross-sectional study of 40 unrelated patients with nCHH.MethodsPatients were screened for mutations in the GNRHR gene by DNA sequencing.ResultsGNRHR mutations were identified in five of 40 patients studied. Four patients had biallelic mutations (including a novel frameshift deletion p.Phe313Metfs*3, in two families) in agreement with autosomal recessive inheritance. One patient had a heterozygous GNRHR mutation associated with a heterozygous PROKR2 mutation, thus suggesting a possible role of synergistic heterozygosity in the pathogenesis of the disorder.ConclusionsThis study further expands the spectrum of known genetic defects associated with nCHH. Although GNRHR mutations are usually biallelic and inherited in an autosomal recessive manner, the presence of a monoallelic mutation in a patient should raise the possibility of a digenic/oligogenic cause of nCHH.

Expanding the genetic spectrum of ANOS1 mutations in patients with congenital hypogonadotropic hypogonadism.

What is the prevalence and functional consequence of ANOS1 (KAL1) mutations in a group of men with congenital hypogonadotropic hypogonadism (CHH)? Three of forty-two (7.1%) patients presented ANOS1 mutations, including a novel splice site mutation leading to exon skipping and a novel contiguous gene deletion associated with ichthyosis. CHH is characterized by lack of pubertal development and infertility, due to deficient production, secretion or action of GnRH, and can be associated with anosmia/hyposmia (Kallmann syndrome, KS) or with a normal sense of smell (normosmic CHH). Mutations in the anosmin-1 (ANOS1) gene are responsible for the X-linked recessive form of KS. This cross-sectional study included 42 unrelated men with CHH (20 with KS and 22 with normosmic CHH). Patients were screened for mutations in the ANOS1 gene by DNA sequencing. Identified mutations were further investigated by RT-PCR analysis and multiplex ligation-dependent probe amplification (MLPA) analysis. Hemizygous mutations were identified in three (7.1%) KS cases: a novel splice acceptor site mutation (c.542-1G>C), leading to skipping of exon 5 in the ANOS1 transcript in a patient with self-reported normosmia (but hyposmic upon testing); a recurrent nonsense mutation (c.571C>T, p.Arg191*); and a novel 4.8 Mb deletion involving ANOS1 and eight other genes (VCX3B, VCX2, PNPLA4, VCX, STS, HDHD1, VCX3A and NLGN4X) in KS associated with ichthyosis. Objective olfactory testing was not performed in all cases of self-reported normosmia and this may have underestimated the olfactory deficits. This study further expands the spectrum of known genetic defects associated with CHH and suggests that patients with self-reported normal olfactory function should not be excluded from ANOS1 genetic testing. This study was funded by the Portuguese Foundation for Science and Technology. The authors have no conflicts of interest. N/A.

Triallelic digenic mutation in the prokineticin 2 and GNRH receptor genes in two brothers with normosmic congenital hypogonadotropic hypogonadism

Purpose/aim of the study: To date, different genes have been identified as responsible for the presence of normosmic congenital hypogonadotropic hypogonadism (nCHH). Herein, we report the molecular findings regarding the analysis of PROK2, in two brothers with nCHH. Subjects and methods: Two siblings with nCHH, in whom mutations in GNRHR, PROKR2 and FGFR1 had been investigated previously, as well as their family were studied. DNA was amplified by PCR and sequenced for the PROK2 gene. Controls were analyzed by restriction fragment-length polymorphism. The structure of PROK2 and its mutant protein were compared using a protein molecular model. Results: Both affected siblings exhibited a heterozygous p.R117W mutation in PROK2, while their mother was a heterozygous carrier and their father, an unaffected brother and their sister were homozygous wild type. Besides, both patients presented a homozygous p.E90K mutation in GNRHR that had been previously reported. Conclusions: We found a novel mutation in PROK2 in two siblings in whom a mutation in the GNRHR gene had been previously reported.

Sex steroids, precursors, and metabolite deficiencies in men with isolated hypogonadotropic hypogonadism and panhypopituitarism: a GCMS-based comparative study.

Both testicular and adrenal steroid secretions are impaired in men with panhypopituitarism (Hypo-Pit), whereas only testicular steroid secretion is impaired in men with isolated gonadotropin deficiency (IHH) caused by normosmic congenital hypogonadotropic hypogonadism or Kallmann syndrome. The objective of the study was to compare the serum levels of sex steroids, precursors, and metabolites between men with complete IHH and those with Hypo-Pit. We studied 42 healthy men, 16 untreated men with IHH (normosmic congenital hypogonadotropic hypogonadism/Kallmann syndrome) and 23 men with Hypo-Pit (14 with craniopharyngioma, 9 with congenital hypopituitarism) receiving hydrocortisone, thyroxine, and GH replacement therapy but not T. Gas chromatography/mass spectrometry (GCMS) was used to measure the serum levels of sex steroids [T, dihydrotestosterone (DHT), and estradiol (E2)], their precursors (pregnenolone, 17-hydroxypregnenolone, dehydroepiandrosterone, androstenediol, progesterone, 17-hydroxyprogesterone, and androstenedione), and their metabolites (androsterone, estrone, and estrone sulfate) as well as pregnenolone and dehydroepiandrosterone sulfate esters. All the above-mentioned steroids, and notably T, DHT, and E2, were significantly lower in IHH patients than in controls but remained well above the detection limit of the relevant assays. In Hypo-Pit men, all these steroids were dramatically and significantly lower than in IHH. Interestingly, T, DHT, and E2, as well as pregnenolone and dehydroepiandrosterone sulfate esters, were undetectable or barely detectable in the Hypo-Pit men. Steroid deficiencies are marked but partial in men with complete IHH. In contrast, men with Hypo-Pit have a very severe overall steroid deficiency. These deficiencies could affect health and quality of life.

Hypogonadismes hypogonadotrophiques congénitaux et syndrome de Kallmann chez l’homme

Congenital hypogonadotropic hypogonadism (CHH) and Kallmann syndrome (KS) are a group of rare disorders responsible for complete or partial pubertal failure due to lack or insufficient secretion of the pituitary gonadotropins LH and FSH. The underlying neuroendocrine abnormalities are classically divided into two main groups: molecular defects of the gonadotrope cascade leading to isolated normosmic CHH (nCHH), and developmental abnormalities affecting the hypothalamic location of GnRH neurons, but also olfactory bulbs and tracts morphogenesis and responsible for KS. Identification of genetic abnormalities related to CHH/KS has provided major insights into the pathways critical for the development, maturation and function of the gonadotrope axis. In patients affected by nCHH, particularly in familial cases, genetic alterations affecting GnRH secretion (mutations in GNRH1, GPR54/KISS1R and TAC3 and TACR3) or the GnRH sensitivity of gonadotropic cells (GNRHR) have been found. Mutations in KAL1, FGFR1/FGF8/FGF17, PROK2/PROKR2, NELF, CHD7, HS6ST1, WDR11, SEMA3A, SOX10, IL17RD2, DUSP6, SPRY4, and FLRT3 have been associated with KS but sometimes also with its milder hyposmic/normosmic CHH clinical variant. A number of observations, particularly in sporadic cases, suggest that CHH/KS is not always a monogenic mendelian disease as previously thought but rather a digenic or potentially oligogenic condition. Before the age of 18 years, the main differential diagnosis of isolated nCHH is the relatively frequent constitutional delay of growth and puberty (CDGP). However, in male patients with pubertal delay and low gonadotropin levels, the presence of micropenis and/or cryptorchidism argues strongly in favor of CHH and against CDGP. CHH/KS are not always congenital life-long disorders as initially thought, because in nearly 10 % of patients the disease seems not permanent, as evidenced by partial recovery of the pulsatile activity of the hypothalamic-pituitary-gonadal axis after discontinuation of treatment in adulthood (the so-called reversible CHH/KS). The clinical and hormonal diagnosis and the therapeutic management as well as the genetic counseling of these patients will be discussed here based on the experience acquired in our department during the past 30 years, from monitoring more than 400 patients with these rare conditions.

R31C GNRH1 Mutation and Congenital Hypogonadotropic Hypogonadism

Normosmic congenital hypogonadotropic hypogonadism (nCHH) is a rare reproductive disease leading to lack of puberty and infertility. Loss-of-function mutations of GNRH1 gene are a very rare cause of autosomal recessive nCHH. R31C GNRH1 is the only missense mutation that affects the conserved GnRH decapeptide sequence. This mutation was identified in a CpG islet in nine nCHH subjects from four unrelated families, giving evidence for a putative “hot spot”. Interestingly, all the nCHH patients carry this mutation in heterozygosis that strikingly contrasts with the recessive inheritance associated with frame shift and non-sense mutations. Therefore, after exclusion of a second genetic event, a comprehensive functional characterization of the mutant R31C GnRH was undertaken. Using different cellular models, we clearly demonstrate a dramatic reduction of the mutant decapeptide capacity to bind GnRH-receptor, to activate MAPK pathway and to trigger inositol phosphate accumulation and intracellular calcium mobilization. In addition it is less able than wild type to induce lh-beta transcription and LH secretion in gonadotrope cells. Finally, the absence of a negative dominance in vitro offers a unique opportunity to discuss the complex in vivo patho-physiology of this form of nCHH.

KISS1Rmutations in normosmic congenital hypogonadotropic hypogonadism: clinical evaluation of two families and molecular characterization of a novel mutation

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Computed Tomography of the Anterior Skull Base in Kallmann Syndrome Reveals Specific Ethmoid Bone Abnormalities Associated With Olfactory Bulb Defects

Kallmann syndrome (KS) is characterized by congenital hypogonadotropic hypogonadism (CHH) and an impaired sense of smell related to defective development of the olfactory system. The aim of the study was to use high-resolution computed tomography (CT) to detect specific abnormalities in the ethmoid bone region surrounding the olfactory bulbs in patients with KS. Thirty-seven KS patients were compared to normosmic CHH (nCHH) patients (n = 15) and controls (n = 30) of similar age. We conducted a prospective study in a single referral center. Subjects underwent CT in bone windows with axial, coronal, and sagittal reconstructions centered on the olfactory fossa (OF) and cribriform plate (CP). We characterized the OF structure by measuring OF height, width, and surface area and a series of angles. The CP foramina were counted bilaterally. Olfactory bulb magnetic resonance imaging, performed in parallel, was compared with CT findings. OF height, width, and surface area were all significantly lower in KS patients than in nCHH patients and controls (P < .0001). KS patients also had wider angles than nCHH patients and controls (P < .0001). KS subjects with olfactory bulb agenesis on magnetic resonance imaging or who harbored KAL1 mutations had the most marked changes in OF measurements and angles. Coronal OF height distinguished KS patients from controls with the best sensitivity and specificity. The mean number of CP foramina was similar in KS, nCHH, and control subjects. KS is associated with specific ethmoid bone abnormalities. The preserved number of CP foramina in KS patients suggests that the integrity of olfactory structures is not mandatory for their formation during fetal development or their maintenance in adult life.

Two Families with Normosmic Congenital Hypogonadotropic Hypogonadism and Biallelic Mutations in KISS1R (KISS1 Receptor): Clinical Evaluation and Molecular Characterization of a Novel Mutation

Context KISS1R mutations have been reported in few patients with normosmic congenital hypogonadotropic hypogonadism (nCHH) (OMIM #146110).ObjectiveTo describe in detail nCHH patients with biallelic KISS1R mutations belonging to 2 unrelated families, and to functionally characterize a novel KISS1R mutation.ResultsAn original mutant, p.Tyr313His, was found in the homozygous state in 3 affected kindred (2 females and 1 male) from a consanguineous Portuguese family. This mutation, located in the seventh transmembrane domain, affects a highly conserved amino acid, perturbs the conformation of the transmembrane segment, and impairs MAP kinase signaling and intracellular calcium release. In the second family, a French Caucasian male patient with nCHH was found to carry two recurrent mutations in the compound heterozygous state (p.Leu102Pro/Stop399Arg). In this man, pulsatile GnRH (Gonadotropin Releasing Hormone) administration restored pulsatile LH (Luteinizing Hormone) secretion and testicular hormone secretion. Later, long-term combined gonadotropin therapy induced spermatogenesis, enabling 3 successive pregnancies that resulted in 2 miscarriages and the birth of a healthy boy.ConclusionWe show that a novel loss-of-function mutation (p.Tyr313His) in the KISS1R gene can cause familial nCHH, revealing the crucial role of this amino acid in KISS1R function. The observed restoration of gonadotropin secretion by exogenous GnRH administration further supports, in humans, the hypothalamic origin of the gonadotropin deficiency in this genetic form of nCHH.