CHARGE syndrome includes hypogonadotropic hypogonadism and abnormal olfactory bulb development

Suppression of BMP signaling restores mitral cell development impaired by FGF signaling deficits in mouse olfactory bulb

Fibroblast growth factors (FGFs) and bone morphogenic proteins (BMPs) play various important roles in the development of the central nervous system. However, the roles of FGF and BMP signaling in the development of the olfactory bulb (OB) are largely unknown. In this study, we first showed the expression of FGF receptors (FGFRs) and BMP receptors (BMPRs) in OB RGCs, radial glial cells (RGCs) in the developing OB, which generate the OB projection neurons, mitral and tufted cells. When the FGF signaling was inhibited by a dominant-negative form of FGFR1 (dnFGFR1), OB RGCs accelerated their state transition to mitral cell precursors without affecting their transcription cascade and fate. However, the mitral cell precursors could not radially migrate to form the mitral cell layer (MCL). In addition, FGF signaling inhibition reduced the expression of a BMP antagonist, Noggin, in the developing OB. When BMP signaling was suppressed by the ectopic expression of Noggin or a dominant-negative form of BMPR1a (dnBMPR1a) in the developing OB, the defect in MCL formation caused by the dnFGFR1 was rescued. However, the dnBMPR1a did not rescue the accelerated state transition of OB RGCs. These results demonstrate that FGF signaling is important for OB RGCs to maintain their self-renewal state and MCL formation. Moreover, the suppression of BMP signaling is required for mitral cells to form the MCL. This study sheds new light on the roles of FGFs and BMPs in OB development.

Anterior Skull Base Abnormalities in Congenital Anosmia

INTRODUCTION

The structures of the skull and the brain are related to each other. Prior work in individuals with isolated congenital anosmia (ICA) showed that these individuals were characterized by olfactory bulb (OB) defects. The aim of this study was to compare the morphological pattern of the anterior skull base surrounding the OB between individuals with ICA and normosmic controls. We meant to investigate whether these features can help distinguish abnormalities from normal variation.

METHODS

We conducted a retrospective study to acquire T2-weighted magnetic resonance images from individuals diagnosed with ICA (n = 31) and healthy, normosmic controls matched for age and gender (n = 62). Between both groups, we compared the depth and width of the olfactory fossa, the angle of the ethmoidal fovea, as well as the angle of the lateral lamella of the cribriform plate. Within the ICA group, we further performed subgroup analyses based on the presence or absence of the OB, to investigate whether the morphology of the anterior skull base relates to the presence of OBs. The diagnostic performance of these parameters was evaluated using receiver operating characteristic analysis.

RESULTS

Individuals with ICA exhibited a flattened ethmoid roof and shallower olfactory fossa when compared to controls. Further, the absence of the OB was found to be associated with a higher degree of flattening of the ethmoid roof and a shallow olfactory fossa. We reached the results in the following areas under the receiver operating characteristic curves: 0.80 - angle of fovea ethmoidalis, 0.76 - depth of olfactory fossa, 0.70 - angle of lateral lamella of the cribriform plate for significant differentiation between individuals with ICA and normosmic controls.

CONCLUSION

Individuals with ICA exhibited an unusual anterior skull base surrounding the OB. This study supports the idea of an integrated development of OB and anterior skull base. Hence, the morphological pattern of the anterior skull base surrounding the OB helps distinguish individuals with ICA from normosmic controls and may therefore be useful for the diagnosis of ICA, although it is certainly not an invariable sign of congenital anosmia.

Combined pituitary hormone deficiency harboring CHD7 gene missense mutation without CHARGE syndrome: a case report

BACKGROUND

Heterozygous loss-of-function mutations in the chromodomain helicase DNA-binding protein 7 (CHD7) gene cause CHARGE syndrome characterized by various congenital anomalies. A majority of patients with CHARGE syndrome present with congenital hypogonadotropic hypogonadism (HH), and combined pituitary hormone deficiency (CPHD) can also be present. Whereas CHD7 mutations have been identified in some patients with isolated HH without a diagnosis of CHARGE syndrome, it remains unclear whether CHD7 mutations can be identified in patients with CPHD who do not fulfill the criteria for CHARGE syndrome.

CASE PRESENTATION

A 33-year-old woman was admitted to our hospital. She had primary amenorrhea and was at Tanner stage 2 for both pubic hair and breast development. She was diagnosed with CPHD (HH, growth hormone deficiency, and central hypothyroidism), and a heterozygous rare missense mutation (c.6745G > A, p.Asp2249Asn) in the CHD7 gene was identified. Our conservation analysis and numerous in silico analyses suggested that this mutation had pathogenic potential. She had mild intellectual disability, a minor feature of CHARGE syndrome, but did not fulfill the criteria for CHARGE syndrome.

CONCLUSIONS

We report a rare case of CPHD harboring CHD7 mutation without CHARGE syndrome. This case provides valuable insights into phenotypes caused by CHD7 mutations. CHD7 mutations can have a continuous phenotypic spectrum depending on the severity of hypopituitarism and CHARGE features. Therefore, we would like to propose a novel concept of CHD7-associated syndrome.

Expanding the reproductive organ phenotype of CHD7-spectrum disorder

CHD7 disorder is a multiple congenital anomaly syndrome with a highly variable phenotypic spectrum, and includes CHARGE syndrome. Internal and external genital phenotypes frequently seen in CHD7 disorder include cryptorchidism and micropenis in males, and vaginal hypoplasia in females, both thought to be secondary to hypogonadotropic hypogonadism. Here, we report 14 deeply phenotyped individuals with known CHD7 variants (9 pathogenic/likely pathogenic and 5 VOUS) and a range of reproductive and endocrine phenotypes. Reproductive organ anomalies were observed in 8 of 14 individuals and were more commonly noted in males (7/7), most of whom presented with micropenis and/or cryptorchidism. Kallmann syndrome was commonly observed among adolescents and adults with CHD7 variants. Remarkably, one 46,XY individual presented with ambiguous genitalia, cryptorchidism with Müllerian structures including uterus, vagina and fallopian tubes, and one 46,XX female patient presented with absent vagina, uterus and ovaries. These cases expand the genital and reproductive phenotype of CHD7 disorder to include two individuals with genital/gonadal atypia (ambiguous genitalia), and one with Müllerian aplasia.

CHARGE syndrome presenting with persistent hypoglycemia: case report and overview of the main genetic syndromes associated with neonatal hypoglycemia

Background

CHARGE syndrome (CS) is an autosomal dominant genetic condition whose recognition in the neonatal period is complicated by considerable phenotypic variability. Pediatric patients with genetic disorders have a known high incidence of hypoglycemia, due to many concurring factors. To date, neonatal hypoglycemia is a feature poorly explored in the literature associated with CS. This paper adds to the existing literature on hypoglycemia in CS and provides a brief review of the mechanisms through which CS, as well as the main genetic syndromes associated with neonatal hypoglycemia, may determine it.

Case presentation

The patient was a term newborn, first-born daughter to non-consanguineous parents. At birth, axial hypotonia with slight hypertonia of the limbs, and dysplastic auricles were noted. The incidental finding of asymptomatic hypoglycemia led to the initiation of glucose infusion on the II day of life, continued for a total of 8 days (maximum infusion rate: 8 mg/kg/min). In-depth endocrinological examinations showed poor cortisol response to the hypoglycemic stimulus, with normal GH values, thyroid function and ACTH. In view of the suspected hypoadrenalism, oral hydrocortisone therapy was initiated. Inappropriately low values of plasmatic and urinary ketones supported the hypothesis of concomitant transient hyperinsulinism, not requiring therapy. A brain MRI was performed, documenting thinning of the optic nerves, non-displayable olfactory bulbs and dysmorphic corpus callosum. An eye examination revealed bilateral chorioretinal coloboma. Temporal bone CT scan showed absence of the semicircular canals. The unexpected findings of coloboma and absence of semicircular canals led to the suspicion of CS, later confirmed by the molecular analysis of CHD7.

Conclusions

It seems important to consider CS in the differential diagnosis of persistent hypoglycemia in newborns with specific anomalies. At the same time, it is advisable to consider the risk of hypoglycemia in children with CS, as well as other genetic syndromes. Awareness of the many possible causes of hypoglycemia in newborns with genetic conditions may help steer the investigations, allowing for an appropriate and timely treatment.

Congenital Micropenis: Etiology And Management

In the newborn, penile length is determined by a number of androgen dependent and independent factors. The current literature suggests that there are interracial differences in stretched penile length in the newborn and although congenital micropenis should be defined as a stretched penile length of less than 2.5 SDS of the mean for the corresponding population and gestation, a pragmatic approach would be to evaluate all boys with a stretched penile length below 2 cm, as congenital micropenis can be a marker for a wide range of endocrine conditions. However, it remains unclear as to whether the state of micropenis, itself, is associated with any long-term consequences. There is a lack of systematic studies comparing the impact of different therapeutic options on long-term outcomes, in terms of genital appearance, quality of life, and sexual satisfaction. To date, research has been hampered by a small sample size and inclusion of a wide range of heterogeneous diagnoses; for these reasons, condition-specific outcomes have been difficult to compare between studies. Lastly, there is a need for a greater collaborative effort in collecting standardized data so that all real-world or experimental interventions performed at an early age can be studied systematically into adulthood.

Endocrinopathies in Inborn Errors of Immunity

Inborn errors of immunity (IEI), caused by hereditary or genetic defects, are a group of more than 400 disorders, in which the immune system, including lymphocytes, neutrophils, macrophages, and complements, does not function properly. The endocrine system is frequently affected by IEI as an associated clinical feature and a complex network of glands which regulate many important body functions, including growth, reproduction, homeostasis, and energy regulation. Most endocrine disorders associated with IEI are hypofunction which would be treated with supplementation therapy, and early diagnosis and appropriate management are essential for favorable long-term outcomes in patients with IEI. In this review, we aimed to comprehensively summarize and discuss the current understanding on the clinical features and the pathophysiology of endocrine disorders in IEI. This review is composed with three parts. First, we discuss the two major pathophysiology of endocrinopathy in IEI, autoimmune response and direct effects of the responsible genes. Next, the details of each endocrinopathy, such as growth failure, hypothyroidism, hypoparathyroidism, adrenal insufficiency, diabetes mellitus (DM) are specified. We also illustrated potential endocrinopathy due to hematopoietic stem cell transplantation, including hypogonadism and adrenal insufficiency due to glucocorticoid therapy.

Unilateral Choanal Atresia: Indications of Long-Term Olfactory Deficits and Volumetric Brain Changes Postsurgically

BACKGROUND

Very few studies have investigated whether unilateral choanal atresia is associated with permanent olfactory deficits.

OBJECTIVE

This study aimed to evaluate the olfactory performance of patients with unilateral choanal atresia postsurgically.

METHODS

Three patients with unilateral atresia were examined in terms of olfactory performance with the Sniffin' Sticks test (odor identification, threshold, and discrimination), size of the olfactory bulb, and volumetric brain changes.

RESULTS

All patients demonstrated significantly lower olfactory performance in terms of odor threshold on the same side with the choanal atresia. Grey matter reductions were found ipsilaterally in the hippocampus.

CONCLUSIONS

This pilot study indicates that persistent olfactory deficits and volumetric brain changes are present in patients with unilateral choanal atresia.

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.

Congenital Hypogonadotropic Hypogonadism with Anosmia and Gorlin Features Caused by a PTCH1 Mutation Reveals a New Candidate Gene for Kallmann Syndrome

BACKGROUND

Two loci (CHD7 and SOX10) underlying Kallmann syndrome (KS) were discovered through clinical and genetic analysis of CHARGE and Waardenburg syndromes, conditions that include congenital anosmia caused by olfactory bulb (CA/OBs) defects and congenital hypogonadotropic hypogonadism (CHH). We hypothesized that other candidate genes for KS could be discovered by analyzing rare syndromes presenting with these signs. Study Design, Size, Duration: We first investigated a family with Gorlin-Goltz syndrome (GGS) in which affected members exhibited clinical signs suggesting KS. Participants/Materials, Methods: Proband and family members underwent detailed clinical assessment. The proband received detailed neuroendocrine evaluation. Genetic analyses included sequencing the PTCH1 gene at diagnosis, followed by exome analyses of causative or candidate KS/CHH genes, in order to exclude contribution to the phenotypes of additional mutations. Exome analyses in additional 124 patients with KS/CHH probands with no additional GGS signs.

RESULTS

The proband exhibited CA, absent OBs on magnetic resonance imaging, and had CHH with unilateral cryptorchidism, consistent with KS. Pulsatile Gonadotropin-releasing hormone (GnRH) therapy normalized serum gonadotropins and increased testosterone levels, supporting GnRH deficiency. Genetic studies revealed 3 affected family members harbor a novel mutation of PTCH1 (c.838G> T; p.Glu280*). This unreported nonsense deleterious mutation results in either a putative truncated Ptch1 protein or in an absence of translated Ptch1 protein related to nonsense mediated messenger RNA decay. This heterozygous mutation cosegregates in the pedigree with GGS and CA with OBs aplasia/hypoplasia and with CHH in the proband suggesting a genetic linkage and an autosomal dominant mode of inheritance. No pathogenic rare variants in other KS/CHH genes cosegregated with these phenotypes. In additional 124 KS/CHH patients, 3 additional heterozygous, rare missense variants were found and predicted in silico to be damaging: p.Ser1203Arg, p.Arg1192Ser, and p.Ile108Met.

CONCLUSION

This family suggests that the 2 main signs of KS can be included in GGS associated with PTCH1 mutations. Our data combined with mice models suggest that PTCH1 could be a novel candidate gene for KS/CHH and reinforce the role of the Hedgehog signaling pathway in pathophysiology of KS and GnRH neuron migration.

Olfactory Malformations in Mendelian Disorders of the Epigenetic Machinery

Usually overlooked by physicians, olfactory abnormalities are not uncommon. Olfactory malformations have recently been reported in an emerging group of genetic disorders called Mendelian Disorders of the Epigenetic Machinery (MDEM). This study aims to determine the prevalence of olfactory malformations in a heterogeneous group of subjects with MDEM. We reviewed the clinical data of 35 patients, 20 females and 15 males, with a mean age of 9.52 years (SD 4.99). All patients had a MDEM and an already available high-resolution brain MRI scan. Two experienced neuroradiologists reviewed the MR images, noting abnormalities and classifying olfactory malformations. Main findings included Corpus Callosum, Cerebellar vermis, and olfactory defects. The latter were found in 11/35 cases (31.4%), of which 7/11 had Rubinstein-Taybi syndrome (RSTS), 2/11 had CHARGE syndrome, 1/11 had Kleefstra syndrome (KLFS), and 1/11 had Weaver syndrome (WVS). The irregularities mainly concerned the olfactory bulbs and were bilateral in 9/11 patients. With over 30% of our sample having an olfactory malformation, this study reveals a possible new diagnostic marker for MDEM and links the epigenetic machinery to the development of the olfactory bulbs.

Neonatal presentation of growth hormone deficiency in CHARGE syndrome: the benefit of early treatment on long-term growth

CHARGE syndrome is a complex disorder involving multiple congenital anomalies and is caused by heterozygous mutations in the CHD7 gene. Growth retardation is a characteristic finding and about 10% of cases present growth hormone (GH) deficiency. GH treatment of short stature in CHARGE syndrome has shown some benefit, but normal height is rarely attained. We report a girl with CHARGE syndrome due to a de novo frameshift mutation in the CHD7 gene (c.2509_2512delCATT), in whom recurrent hypoglycaemia led to the diagnosis of GH deficiency in the second month of life. Early initiation of treatment with recombinant GH resulted in normal growth over ten years of follow-up. This case is the youngest reported CHARGE patient to be diagnosed and treated for GH deficiency and demonstrates that GH deficiency in CHARGE syndrome may manifest early in life through hypoglycaemia, before growth retardation is noted, and can be successfully treated with recombinant GH.

CHARGE syndrome

The article provides literature data and description of the clinical case of CHARGE syndrome with an autosomal – dominant type of inheritance in a child of 3 years and 7 months. The name of the syndrome is formed by the first letters of the characteristic congenital malformations: “C” (coloboma) – optic disc coloboma, “H” (heart defects) – cardiovascular abnormalities, “A” (atresia of choanae) – atresia or stenosis of choan, “R” (retardation of growth and development) – growth deficit, developmental delay, “G” (genital anomalies) – genital anomalies, “E” (ear abnormalities and sensorineural hearing loss) – hearing organ abnormalities. A feature of the clinical case is the early diagnosis of CHARGE syndrome, manifested by bilateral optic disc coloboma; unilateral paresis of the facial nerve; congenital heart disease (open aortic duct); retardation of growth, psychomotor and psycho-speech development; cryptorchidism; bilateral anomaly of the outer ear (short, wide, absence of the lobe and external curl), sensorineural hearing loss; bilateral renal hypopalasia, chronic kidney disease.

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.

Temporal bone and intracranial abnormalities in syndromic causes of hearing loss: an updated guide

PURPOSE

To describe in detail the temporal bone and brain findings in both common and rare syndromic causes of hearing loss, with the purpose of broadening among radiologists and enhance the current understanding of distinct imaging features in paediatric patients with syndromic hearing loss.

METHODS

A detailed search of electronic databases has been conducted, including PubMed, Ovid Medline, Scopus, Cochrane Library, Google Scholar, National Institute for Health and Care Excellence (NICE), Embase, and PsycINFO.

RESULTS

Syndromic causes of hearing loss are characterised by different and sometimes specific abnormalities in the temporal bone.

CONCLUSION

A complete knowledge of the image findings in the temporal bones, brain, skull and other body regions is critical for the optimal assessment and management of these patients.

Growth in CHARGE syndrome: optimizing care with a multidisciplinary approach

CHARGE (Coloboma of the eye, Heart defects, Atresia of the choanae, Retardation of growth and/or development, Genital hypoplasia, Ear anomalies including hearing loss) syndrome is a rare syndrome with an incidence of approximately 1:15,000 newborns. It is caused by pathogenic variants in the CHD7 gene and clinically characterized by a wide range of anomalies with variable expression. Growth retardation affects 60-72% of children with CHARGE syndrome, making it one of the most prominent medical issues in the syndrome. Growth retardation in CHARGE syndrome is thought to be multifactorial and can be influenced by almost all co-morbidities, requiring a multidisciplinary approach to the different medical problems. In this systematic review, we describe what is currently known about growth in CHARGE syndrome and how it is influenced by commonly seen clinical problems including feeding difficulties, hypogonadotropic hypogonadism and growth hormone deficiency. Furthermore, we provide recommendations for a multidisciplinary approach.

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.

An analysis of body proportions in children with CHARGE syndrome using photogrammetric anthropometry

Background

Growth retardation is one of the main hallmarks of CHARGE syndrome (CS), yet little is known about the body proportions of these children. Knowledge of body proportions in CS may contribute to a better characterization of this syndrome. This knowledge is important when considering starting growth‐stimulating therapy.

Methods

For this cross‐sectional study, we selected 32 children with CS and a CHD7 mutation at the Dutch CHARGE Family Day in 2016 or 2017 and the International CHARGE conference in Orlando, Florida, in 2017. We used photogrammetric anthropometry—a measurement method based on digital photographs—to determine various body proportions. We compared these to measurements in 21 normally proportioned children with growth hormone deficiency, using independent‐samples t test, Mann–Whitney U test, or chi‐square test as appropriate.

Results

Children with CS appear to have a shorter trunk in proportion to their height, head length, and arm length. Children with CS also had smaller feet proportional to tibia length compared to controls. The change of body proportions with age was similar in children with CS and controls.

Conclusion

Body proportions in children with CS are significantly different from those of normally proportioned controls, but a similar change of body proportions with age was noted for both groups.

Development of the human olfactory system

This chapter focuses on the development of the human olfactory system. In this system, function does not require full neuroanatomical maturity. Thus, discrimination of odorous molecules, including a number within the mother's diet, occurs in amniotic fluid after 28-30 weeks of gestation, at which time the olfactory bulbs are identifiable by MRI. Hypoplasia/aplasia of the bulbs is documented in the third trimester and postnatally. Interestingly, olfactory axons project from the nasal epithelium to the telencephalon before formation of the olfactory bulbs and lack a peripheral ganglion, but the synaptic glomeruli of the future olfactory bulb serves this function. Histologic lamination of the olfactory bulb is present by 14 weeks, but maturation remains incomplete at term for neuronal differentiation, synaptogenesis, myelination, and persistence of the normal transitory fetal ventricular recess. Myelination occurs postnatally. Although olfaction is the only sensory system without direct thalamic projections, the olfactory bulb and anterior olfactory nucleus are, in effect, thalamic surrogates. For example, many dendro-dendritic synapses occur within the bulb between GABAergic granular neurons and periglomerular neurons. Moreover, bulbar synaptic glomeruli are analogous to peripheral ganglia of other sensory cranial nerves. The olfactory tract contains much gray as well as white matter. The olfactory epithelium and bulb both incorporate progenitor cells at all ages. Diverse malformations of the olfactory bulb can be detected by clinical examination, imaging, and neuropathology; indeed, olfactory reflexes of the neonate can be reliably tested. We recommend that such testing be routine in the neonatal neurologic examination, especially in children with brain malformations, endocrinopathies, chromosomopathies, genetic/metabolic disorders, and perinatal hypoxic/ischemic encephalopathy.

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.

Head and Neck MRI Findings in CHARGE Syndrome

Coloboma of the eye, Heart defects, Atresia of the choanae, Retardation of growth and/or development, Genital and/or urinary abnormalities, and Ear abnormalities and deafness (CHARGE) syndrome is a disorder with multiple congenital anomalies seen on imaging. A retrospective review of 10 patients with CHARGE syndrome who underwent MR imaging of the brain as part of a preoperative evaluation for cochlear implantation was conducted. Structural abnormalities of the entire MR imaging of the head were evaluated, including the auditory system, olfactory system, face, skull base, and central nervous system. The most frequent MR imaging findings included dysplasias of the semicircular canals and hypoplasia of the frontal lobe olfactory sulci. Less frequent findings included cleft lip/palate and coloboma. Our study uncovered new findings of a J-shaped sella, dorsal angulation of the clivus, and absent/atrophic parotid glands, not previously described in patients with CHARGE. Our results emphasize the utility of MR imaging in the diagnosis and management of patients with CHARGE syndrome.

Guidelines in CHARGE syndrome and the missing link: Cranial imaging

"CHARGE syndrome" is a complex syndrome with high and extremely variable comorbidity. As a result, clinicians may struggle to provide accurate and comprehensive care, and this has led to the publication of several clinical surveillance guidelines and recommendations for CHARGE syndrome, based on both single case observations and cohort studies. Here we perform a structured literature review to examine all the existing advice. Our findings provide additional support for the validity of the recently published Trider checklist. We also identified a gap in literature when reviewing all guidelines and recommendations, and we propose a guideline for neuroradiological evaluation of patients with CHARGE syndrome. This is of importance, as patients with CHARGE are at risk for peri-anesthetic complications, making recurrent imaging procedures under anesthesia a particular risk in clinical practice. However, comprehensive cranial imaging is also of tremendous value for timely diagnosis, proper treatment of symptoms and for further research into CHARGE syndrome. We hope the guideline for neuroradiological evaluation will help clinicians provide efficient and comprehensive care for individuals with CHARGE syndrome.

Reproductive endocrine phenotypes relating to CHD7 mutations in humans

Mutations in the gene CHD7 cause CHARGE syndrome, a rare multi-organ syndromic disorder. Gonadal defects are common in individuals with CHARGE syndrome (seen in ∼60-80% of cases) and represent the letter "G" in the CHARGE syndrome acronym. The gonadal defect in CHARGE syndrome results from congenital deficiency of the hypothalamic hormone Gonadotropin-releasing hormone (GnRH), which manifests clinically as pubertal failure and infertility, and biochemically as hypogonadotropic hypogonadism (low sex steroid hormone levels with inappropriately normal or low gonadotropin levels). In addition to the gonadal endocrine abnormalities, in a small minority of individuals with CHARGE, additional endocrine defects including growth hormone deficiency, multiple pituitary hormone deficits and primary hypothyroidism may also be seen. CHD7 mutations disrupt the targeting of olfactory axons and the migration of GnRH-synthesizing neurons during embryonic development, resulting in congenital idiopathic hypogonadotropic hypogonadism (IHH) and anosmia (or hyposmia), two features that define human Kallmann syndrome. Since Kallmann syndrome is one of the constituent phenotypes within CHARGE, recent studies have investigated the role of CHD7 mutations in individuals with IHH and established that deleterious missense mutations in CHD7 are associated with Kallmann syndrome as well as normosmic form of IHH. These missense mutations affect the ATPase and nucleosome remodeling activities of the CHD7 protein. These observations suggest that CHD7 protein function is critical for the ontogeny of GnRH neurons and neuroendocrine regulation of GnRH secretion.

Versatile Roles of the Chromatin Remodeler CHD7 during Brain Development and Disease

CHD7 (Chromo-Helicase-DNA binding protein 7) protein is an ATP-dependent chromatin remodeler. Heterozygous mutation of the CHD7 gene causes a severe congenital disease known as CHARGE syndrome. Most CHARGE syndrome patients have brain structural anomalies, implicating an important role of CHD7 during brain development. In this review, we summarize studies dissecting developmental functions of CHD7 in the brain and discuss pathogenic mechanisms behind neurodevelopmental defects caused by mutation of CHD7. As we discussed, CHD7 protein exhibits a remarkably specific and dynamic expression pattern in the brain. Studies in human and animal models have revealed that CHD7 is involved in multiple developmental lineages and processes in the brain. Mechanistically, CHD7 is essential for neural differentiation due to its transcriptional regulation in progenitor cells.

Kallmann syndrome in pediatric otorhinolaryngology practice - Case report and literature review

BACKGROUND

Kallmann syndrome (KS) is an isolated form of hypogonadotrophic hypogonadism (HH) in combination with a defect in olfactory function. The diagnosis of KS before maturation is often difficult to make due to the broad spectrum of presentation and genetic heterogeneities. ENT examination including smell test is essential for proper diagnosis of olfactory disturbances and non olfactory abnormalities in craniofacial region which may also be existent in KS.

CASE

A 17-year-old girl admitted to ENT Department because of the olfactory sense disturbances since two years. The patient reported also amenorrhea caused by primary HH. A diagnostic work-up using double-checked Sniffin' Sticks test and 6-items olfactory test confirmed serious hyposmia and identified the presence of KS.

CONCLUSION

Usually anosmia is not recognized by the affected individuals, so it is recommended to perform olfactory screening tests and obligatory ENT examination in the event of a HH even when patient reports a normal sense of smell. It leads to early diagnosis of KS and will benefit the relevant patient care.The KS diagnosis should be done at an early stage, but symptoms and clinical manifestations are not always evident both in ENT and pediatric field. In this article we would like to highlight the need for a multidisciplinary assessment and awareness for KS symptoms in pediatric practice as a hole.

Suprameatal Cochlear Implantation in a CHARGE Patient With a Novel CHD7 Variant and KALLMANN Syndrome Phenotype: A Case Report

OBJECTIVE

We present the clinical findings, technique of the suprameatal cochlear implantation, postoperative auditory results, and genetic analysis of the CHD7 gene.

PATIENT

A 19-year-old Japanese woman was referred because of progressive hearing loss since early childhood. She had used verbal language for the main mode of communication until the age of 17. Examination revealed coloboma, heart defect, choanal atresia, genital hypoplasia, and deafness, which was diagnosed as CHARGE syndrome. Examination also revealed features of Kallmann syndrome.

INTERVENTIONS

Cochlear implantation was performed in the left ear at age 20. Targeted resequencing of the CHD7 gene was performed by next-generation sequencing.

RESULTS

Cochlear implantation was performed using a suprameatal approach (SMA) with cartilage protection because of a venous malformation of the temporal bone. The electrode introduced into the scala tympani through the cochleostomy could be fully inserted. The electrode was covered with cartilage to avoid contact with the skin of the external auditory canal. No intra- or postoperative complications have occurred up to 4 years postoperatively, and the patient uses verbal language again as the main mode of communication. A novel variant c.6405_6406delAG,p.(Ala2137Argfs*2) in CHD7 was identified by next-generation and Sanger sequencing analyses, resulting in a 2137-amino-acid truncated polypeptide. Parental genetic screening confirmed the sporadic origin of the mutation.

CONCLUSION

Cochlear implantation surgery using the SMA with cartilage protection technique appears to be a feasible and effective option for patients with ear anomalies that obstruct the usual approach. A novel frameshift variant c.6405_6406delAG,p.(Ala2137Argfs*2) in CHD7 was also identified in this patient.

Olfactory Development, Part 2: Neuroanatomic Maturation and Dysgeneses

Olfactory axons project from nasal epithelium to the primitive telencephalon before olfactory bulbs form. Olfactory bulb neurons do not differentiate in situ but arrive via the rostral migratory stream. Synaptic glomeruli and concentric laminar architecture are unlike other cortices. Fetal olfactory maturation of neuronal differentiation, synaptogenesis, and myelination remains incomplete at term and have a protracted course of postnatal development. The olfactory ventricular recess involutes postnatally but dilates in congenital hydrocephalus. Olfactory bulb, tract and epithelium are repositories of progenitor stem cells in fetal and adult life. Diverse malformations of the olfactory bulb can be diagnosed by clinical examination, imaging, and neuropathologically. Cellular markers of neuronal differentiation and synaptogenesis demonstrate immaturity of the olfactory system at birth, previously believed by histology alone to occur early in fetal life. Immaturity does not preclude function.

Expanding the CHARGE Geno-Phenotype: A Girl with Novel CHD7 Deletion, Hypogonadotropic Hypogonadism, and Agenesis of Uterus and Ovaries

BACKGROUND

CHARGE syndrome is a variable entity. Clinical diagnosis is based on the Blake-Verloes criteria and can be confirmed by identifying a mutation or deletion in the CHD7 gene. Hypoplasia of the male genitalia and lack or incomplete secondary sexual development in both sexes is a common feature, and is most often attributable to hypogonadotropic hypogonadism which is described in >80% of the CHARGE patients. Other genital anomalies in CHARGE patients are rare.

METHODS AND RESULTS

We describe the case of a girl with a novel heterozygous deletion in exon 15 of the CHD7 gene and combined agenesis of uterus and ovaries, besides gonadotropin deficiency, thus expanding the geno-phenotype of CHARGE syndrome.

CONCLUSION

In case of persistent primary amenorrhea, despite estrogen replacement, this unusual combination should be considered in girls with CHARGE syndrome.

Central Adrenal Insufficiency Is Not a Common Feature in CHARGE Syndrome: A Cross-Sectional Study in 2 Cohorts

OBJECTIVE

To evaluate whether central adrenal insufficiency (CAI) is present in CHARGE (Coloboma of the eye, Heart defects, Atresia of the choanae, Retardation of growth and/or development, Genital hypoplasia, and Ear abnormalities, including deafness) syndrome, a complex malformation disorder that includes central endocrine dysfunction.

STUDY DESIGN

Two cross-sectional studies were performed in Dutch (September 2013-February 2015) and Australian (January 2012-January 2014) CHARGE syndrome clinics. Twenty-seven Dutch and 19 Australian patients (aged 16 months-18 years) with genetically confirmed CHARGE syndrome were included. The low-dose adrenocorticotropin (ACTH) test was used to assess CAI in the Dutch cohort. A peak cortisol response less than 18.1 μg/dL (500 nmol/L) was suspected for CAI, and a glucagon stimulation test was performed for confirmation. Australian patients were screened by single measurements of ACTH and cortisol levels. If adrenal dysfunction was suspected, a standard-dose ACTH test was performed.

RESULTS

The low-dose ACTH test was performed in 23 patients (median age 8.4 [1.9-16.9] years). Seven patients showed an insufficient maximum cortisol level (10.3-17.6 μg/dL, 285-485 nmol/L), but CAI was confirmed by glucagon stimulation test in only 1 patient (maximum cortisol level 15.0 μg/dL, 415 nmol/L). In the Australian cohort, 15 patients (median age 9.1 [1.3-17.8] years) were screened, and none had CAI.

CONCLUSIONS

CAI was not common in our cohorts, and routine testing of adrenal function in children with CHARGE syndrome is not indicated.

Ultrasound evaluation of development of olfactory sulci in normal fetuses: a possible role in diagnosis of CHARGE syndrome

OBJECTIVES

To describe the timing of the ultrasound appearance of olfactory sulci in normal fetuses, according to gestational age.

METHODS

Olfactory sulci were assessed prospectively in the coronal plane on routine brain ultrasound examination in 100 normal fetuses between 22 and 31 + 6 weeks' gestation. Examinations were divided into five groups according to gestational age: Group 1, 22 to 23 + 6 weeks (n = 22); Group 2, 24 to 25 + 6 weeks (n = 9); Group 3, 26 to 27 + 6 weeks (n = 25); Group 4, 28 to 29 + 6 weeks (n = 22) and Group 5, 30 to 31 + 6 weeks (n = 22). For each fetus, olfactory sulci were assessed as absent, developing or formed.

RESULTS

Developing sulci appeared as primitive smooth depressions in the frontal lobe, which evolved into deep sharp complete sulci in later pregnancy. It was possible to assess the development of sulci in all cases. Olfactory sulci were consistently absent in Group 1. In Group 2, 44.4% of fetuses had absent olfactory sulci and 55.6% had developing sulci. In Group 3, the olfactory sulci were still developing in 21 (84.0%) fetuses and were completely formed in four (16.0%). Sulci were completely formed in all fetuses in Groups 4 and 5.

CONCLUSIONS

Fetal brain ultrasound can visualize developing olfactory sulci from as early as 24 weeks' gestation. After 26 weeks, fetuses have detectable olfactory sulci and, after 28 weeks, they are completely formed. Abnormal development of olfactory sulci is a key feature of CHARGE syndrome. These results may help to improve the prenatal diagnosis of CHARGE syndrome. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Short Children with CHARGE Syndrome: Do They Benefit from Growth Hormone Therapy?

AIM

The aim of this study was to evaluate the response to recombinant growth hormone (GH) treatment in short children with CHARGE syndrome.

PATIENTS

We identified 51 children (28 boys and 23 girls) in KIGS (Pfizer International Growth Database). The median chronological age was 7.6 years at the start of GH therapy and 13.2 years at the latest visit. Evaluation for GH deficiency (n = 33) was based on the following: peak GH level 7.3 μg/l and IGF-I level -2.01 standard deviation score (SDS). Sixteen subjects (9 boys) were followed longitudinally for 2 years.

RESULTS

Birth length (median SDS, -0.47) and weight (-0.97) were slightly reduced. At the start of GH therapy, height was -3.6 SDS, BMI -0.7 SDS, and the GH dose was 0.26 mg/kg/week. At the latest visit after 2.7 years of GH therapy, height had increased to -2.2 SDS and BMI to -0.5 SDS. In the longitudinal group, height increased from -3.72 SDS at the start of GH therapy to -2.92 SDS after 1 year to -2.37 SDS after 2 years of therapy (start - 2 years: p < 0.05), height velocity increased from -1.69 to 2.98 to 0.95 SDS, and BMI and GH dose (mg/kg/week) remained almost unchanged.

CONCLUSIONS

Our data show a positive effect of conventional doses of GH on short-term growth velocity for the longitudinal as well as for the total group, without any safety issues.

Maturation and Dysgenesis of the Human Olfactory Bulb

The olfactory bulb with its unique architecture was studied for neuronal maturation in human fetuses. Neuroblasts stream into the olfactory bulb from the rostral telencephalon and secondarily migrate radially. The transitory olfactory ventricular recess regresses postnatally. Olfactory is the only sensory system without thalamic projections but incorporates intrinsic thalamic equivalents. The bulb is a repository of progenitor cells. Maturation of the bulb and tract was studied in 18 normal human fetuses of 16-41 weeks gestation; mid-gestational twins with hydrocephalus; 7 arrhinencephaly/holoprosencephaly; 2 olfactory dysgeneses. Multiple immunoreactivities were performed. Synaptophysin around mitral neurons, in a few synaptic glomeruli and concentric lamination of the outer granular layer, was seen at 16 weeks. Outer granular neurons exhibited NeuN at 16 weeks, only 2/3 were reactive at term. Concentric alternating sheets of granular neurons and their dendrodendritic synapses are seen during maturation. Calretinin reactivity is seen in neurons and neurites, primary olfactory nerve axons, periglomerular cells and neuroepithelial cells surrounding the ventricular recess; reactivity occurs later in synaptic glomeruli than with synaptophysin; not all glomeruli are strongly reactive even at term. Nestin- and vimentin-reactive bipolar progenitor cells were demonstrated at all ages and extend into the olfactory tract. Myelin is demonstrated by Luxol fast blue (LFB) only postnatally. In hydrocephalus, the olfactory recess is dilated. Mitral cell dispersion, disrupted glomeruli, heterotopia and maturational delay are seen in some dysgeneses. Malformations exhibit unique findings. Fusion of hypoplastic bulbs can occur. Abnormal architecture is seen in hemimegalencephaly. More documentation of olfactory dysgenesis is needed in other major brain malformations.

Perspectives in Pediatric Pathology, Chapter 14. Natural History of Undescended Testes

Cryptorchidism is one of the most frequent problems encountered in pediatric urology. Its causes, associated lesions, and prognosis in terms of fertility have been a source of interest and discrepancies for pediatric pathologists and urological surgeons.

RNA-seq analysis of developing olfactory bulb projection neurons

Transmission of olfactory information to higher brain regions is mediated by olfactory bulb (OB) projection neurons, the mitral and tufted cells. Although mitral/tufted cells are often characterized as the OB counterpart of cortical projection neurons (also known as pyramidal neurons), they possess several unique morphological characteristics and project specifically to the olfactory cortices. Moreover, the molecular networks contributing to the generation of mitral/tufted cells during development are largely unknown. To understand the developmental patterns of gene expression in mitral/tufted cells in the OB, we performed transcriptome analyses targeting purified OB projection neurons at different developmental time points with next-generation RNA sequencing (RNA-seq). Through these analyses, we found 1202 protein-coding genes that are temporally differentially-regulated in developing projection neurons. Among them, 388 genes temporally changed their expression level only in projection neurons. The data provide useful resource to study the molecular mechanisms regulating development of mitral/tufted cells. We further compared the gene expression profiles of developing mitral/tufted cells with those of three cortical projection neuron subtypes, subcerebral projection neurons, corticothalamic projection neurons, and callosal projection neurons, and found that the molecular signature of developing olfactory projection neuron bears resemblance to that of subcerebral neurons. We also identified 3422 events that change the ratio of splicing isoforms in mitral/tufted cells during maturation. Interestingly, several genes expressed a novel isoform not previously reported. These results provide us with a broad perspective of the molecular networks underlying the development of OB projection neurons.

Congenital Hypogonadotropic Hypogonadism and Kallmann Syndrome: Past, Present, and Future

The proper development and coordination of the hypothalamic-pituitary-gonadal (HPG) axis are essential for normal reproductive competence. The key factor that regulates the function of the HPG axis is gonadotrophin-releasing hormone (GnRH). Timely release of GnRH is critical for the onset of puberty and subsequent sexual maturation. Misregulation in this system can result in delayed or absent puberty and infertility. Congenital hypogonadotropic hypogonadism (CHH) and Kallmann syndrome (KS) are genetic disorders that are rooted in a GnRH deficiency but often accompanied by a variety of non-reproductive phenotypes such as the loss of the sense of smell and defects of the skeleton, eye, ear, kidney, and heart. Recent progress in DNA sequencing technology has produced a wealth of information regarding the genetic makeup of CHH and KS patients and revealed the resilient yet complex nature of the human reproductive neuroendocrine system. Further research on the molecular basis of the disease and the diverse signal pathways involved will aid in improving the diagnosis, treatment, and management of CHH and KS patients as well as in developing more precise genetic screening and counseling regime.

Spontaneous postnatal growth is reduced in children with CHARGE syndrome

AIM

There is a scarcity of data on postnatal growth in children with CHARGE syndrome, a genetic disorder. This study analysed spontaneous growth and weight in German children with CHARGE from birth to the age of 6 years.

METHODS

This was a retrospective analysis of 19 children, nine females and 10 males, using data from child health records. Standard deviation scores (SDS) were calculated based on Swiss references.

RESULTS

The median birthweight was 2950 g (-0.78 SDS), and the birth length was 49 cm (-0.5 SDS). There was a significant loss of median body length, at around 4 weeks of age from -0.5 to -2.3 SDS (p < 0.05). At 1 year, the median length was -2.6 SDS and it remained low until 5 years of age when the lowest value was found to be -2.8 SDS. There was a significant increase in median body mass index (BMI) from -1.15 SDS at 1 year to -0.15 SDS at 5 years (p < 0.01).

CONCLUSION

Children with CHARGE syndrome displayed almost normal length and weight data at birth, with just one of the 19 infants having below average length for gestational age. However, postnatal growth was retarded during infancy and childhood, and the increase in BMI-SDS did not correlate with growth.

CHARGE syndrome and Cochlear implantation: difficulties and outcomes in the paediatric population

OBJECTIVES

CHARGE syndrome is a complex cluster of congenital abnormalities, these children may have absent or hypoplastic auditory nerves. Our objective was to assess preoperative factors and outcomes for paediatric cochlear implant recipients with CHARGE syndrome, to enable better surgical preparation and family counselling.

METHODS

The Sydney Cochlear Implant Centre database was searched for children with CHARGE syndrome who had received a cochlear implant at ages 16 and less. Data were collected regarding clinical history; hearing assessments; MRI and CT scan findings; preoperative transtympanic electrical Auditory Brainstem Response (ABR); intraoperative findings and intraoperative electrical ABR and Neural Response Telemetry; and language outcomes in terms of main language used and Categories of Auditory Performance scores (0-7 ranking).

RESULTS

Ten children were identified. All seven prelingual profoundly deaf children with CHARGE syndrome had hypoplastic or absent auditory nerves bilaterally on MRI scans. Middle ear anatomy was often abnormal, affecting surgical landmarks and making identification of the cochlea very difficult in some cases. Three cases required repeated surgery to obtain successful cochlear implant insertion, one under CT scan image guided technique. All seven children used sign language, or simpler gestures, as their main mode of communication. Two children of of these children, who were implanted early, also attained some spoken language. CAP scores ranged from 0 to 6. The three children with CHARGE syndrome and progressive sensorineural hearing loss had a normal auditory nerve in at least one ear on MRI scans. All had preoperative verbal language, with CAP scores of 6, and continued with CAP scores of 6 following receipt of the cochlear implant.

CONCLUSION

Children with CHARGE and congenital profound hearing loss all had hypoplasia or absent auditory nerves, affecting their outcomes with cochlear implants. They often had markedly abnormal middle ear anatomy and CT image guided surgery can be helpful. These children should be offered a bilingual early intervention approach, using sign language and verbal language, to ensure best language outcomes. Children with CHARGE syndrome and progressive profound hearing loss did well with cochlear implants and continue to be able to use verbal language.

Chromodomain helicase DNA-binding proteins in stem cells and human developmental diseases

Dynamic regulation of gene expression is vital for proper cellular development and maintenance of differentiated states. Over the past 20 years, chromatin remodeling and epigenetic modifications of histones have emerged as key controllers of rapid reversible changes in gene expression. Mutations in genes encoding enzymes that modify chromatin have also been identified in a variety of human neurodevelopmental disorders, ranging from isolated intellectual disability and autism spectrum disorder to multiple congenital anomaly conditions that affect major organ systems and cause severe morbidity and mortality. In this study, we review recent evidence that chromodomain helicase DNA-binding (CHD) proteins regulate stem cell proliferation, fate, and differentiation in a wide variety of tissues and organs. We also highlight known roles of CHD proteins in human developmental diseases and present current unanswered questions about the pleiotropic effects of CHD protein complexes, their genetic targets, nucleosome sliding functions, and enzymatic effects in cells and tissues.

Functionally compromised CHD7 alleles in patients with isolated GnRH deficiency

Inactivating mutations in chromodomain helicase DNA binding protein 7 (CHD7) cause CHARGE syndrome, a severe multiorgan system disorder of which Isolated gonadotropin-releasing hormone (GnRH) deficiency (IGD) is a minor feature. Recent reports have described predominantly missense CHD7 alleles in IGD patients, but it is unclear if these alleles are relevant to causality or overall genetic burden of Kallmann syndrome (KS) and normosmic form of IGD. To address this question, we sequenced CHD7 in 783 well-phenotyped IGD patients lacking full CHARGE features; we identified nonsynonymous rare sequence variants in 5.2% of the IGD cohort (73% missense and 27% splice variants). Functional analyses in zebrafish using a surrogate otolith assay of a representative set of these CHD7 alleles showed that rare sequence variants observed in controls showed no altered function. In contrast, 75% of the IGD-associated alleles were deleterious and resulted in both KS and normosmic IGD. In two families, pathogenic mutations in CHD7 coexisted with mutations in other known IGD genes. Taken together, our data suggest that rare deleterious CHD7 alleles contribute to the mutational burden of patients with both KS and normosmic forms of IGD in the absence of full CHARGE syndrome. These findings (i) implicate a unique role or preferential sensitivity for CHD7 in the ontogeny of GnRH neurons, (ii) reiterate the emerging genetic complexity of this family of IGD disorders, and (iii) demonstrate how the coordinated use of well-phenotyped cohorts, families, and functional studies can inform genetic architecture and provide insights into the developmental biology of cellular systems.

CHARGE syndrome: a review

CHARGE syndrome is a complex genetic syndrome, owing to the wide range of tissues/systems affected by mutations in the CHD7 gene. In this review, we discuss the diagnosis, clinical features and management of CHARGE syndrome.

Effect of long-term GH treatment in a patient with CHARGE association

CHARGE association is characterized by ocular Coloboma, Heart malformations, choanal Atresia, Retardation of growth and development, Genital abnormalities and inner and external Ear abnormalities. Growth failure is a frequent find mainly associated with feeding difficulties or systemic diseases. To date, GH deficiency has been reported in only few patients with CHARGE association however long-term effects of GH treatment, up to final height, have never been reported. We describe a patient with CHARGE association and GH deficiency treated with GH from the age of 3 years and 10 months up to adult height.

CHD7, the gene mutated in CHARGE syndrome, regulates genes involved in neural crest cell guidance

Heterozygous loss of function mutations in CHD7 (chromodomain helicase DNA-binding protein 7) lead to CHARGE syndrome, a complex developmental disorder affecting craniofacial structures, cranial nerves and several organ systems. Recently, it was demonstrated that CHD7 is essential for the formation of multipotent migratory neural crest cells, which migrate from the neural tube to many regions of the embryo, where they differentiate into various tissues including craniofacial and heart structures. So far, only few CHD7 target genes involved in neural crest cell development have been identified and the role of CHD7 in neural crest cell guidance and the regulation of mesenchymal-epithelial transition are unknown. Therefore, we undertook a genome-wide microarray expression analysis on wild-type and CHD7 deficient (Chd7 (Whi/+) and Chd7 (Whi/Whi)) mouse embryos at day 9.5, a time point of neural crest cell migration. We identified 98 differentially expressed genes between wild-type and Chd7 (Whi/Whi) embryos. Interestingly, many misregulated genes are involved in neural crest cell and axon guidance such as semaphorins and ephrin receptors. By performing knockdown experiments for Chd7 in Xenopus laevis embryos, we found abnormalities in the expression pattern of Sema3a, a protein involved in the pathogenesis of Kallmann syndrome, in vivo. In addition, we detected non-synonymous SEMA3A variations in 3 out of 45 CHD7-negative CHARGE patients. In summary, we discovered for the first time that Chd7 regulates genes involved in neural crest cell guidance, demonstrating a new aspect in the pathogenesis of CHARGE syndrome. Furthermore, we showed for Sema3a a conserved regulatory mechanism across different species, highlighting its significance during development. Although we postulated that the non-synonymous SEMA3A variants which we found in CHD7-negative CHARGE patients alone are not sufficient to produce the phenotype, we suggest an important modifier role for SEMA3A in the pathogenesis of this multiple malformation syndrome.

[Congenital hypogonadotropic hypogonadism and Kallmann syndrome in males]

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.

CHD7 and retinoic acid signaling cooperate to regulate neural stem cell and inner ear development in mouse models of CHARGE syndrome

CHARGE syndrome is a multiple congenital anomaly disorder that leads to life-threatening birth defects, such as choanal atresia and cardiac malformations as well as multiple sensory impairments, that affect hearing, vision, olfaction and balance. CHARGE is caused by heterozygous mutations in CHD7, which encodes an ATP-dependent chromatin remodeling enzyme. Identification of the mechanisms underlying neurological and sensory defects in CHARGE is a first step toward developing treatments for CHARGE individuals. Here, we used mouse models of Chd7 deficiency to explore the function of CHD7 in the development of the subventricular zone (SVZ) neural stem cell niche and inner ear, structures that are important for olfactory bulb neurogenesis and hearing and balance, respectively. We found that loss of Chd7 results in cell-autonomous proliferative, neurogenic and self-renewal defects in the perinatal and mature mouse SVZ stem cell niche. Modulation of retinoic acid (RA) signaling prevented in vivo inner ear and in vitro neural stem cell defects caused by Chd7 deficiency. Our findings demonstrate critical, cooperative roles for RA and CHD7 in SVZ neural stem cell function and inner ear development, suggesting that altered RA signaling may be an effective method for treating Chd7 deficiency.