Asymptomatic laryngeal malformations are common in patients with Pallister-Hall syndrome

Disrupted endosomal trafficking of the Vangl-Celsr polarity complex underlies congenital anomalies in trachea-esophageal morphogenesis

Disruptions in foregut morphogenesis can result in life-threatening conditions where the trachea and esophagus fail to separate properly, such as esophageal atresia (EA) and tracheoesophageal fistulas (TEF). The developmental basis of these congenital anomalies is poorly understood, but recent genome sequencing reveals that de novo variants in intracellular trafficking genes are enriched in EA/TEF patients. Here we show that mutation of orthologous genes in Xenopus disrupts trachea-esophageal separation similar to EA/TEF patients. We show that the Rab11a recycling endosome pathway is required to localize Vangl-Celsr polarity complexes at the cell surface where opposite sides of the common foregut tube fuse. Partial loss of endosome trafficking or the Vangl/Celsr complex disrupts epithelial polarity and cell division orientation. Mutant cells accumulate at the fusion point, fail to downregulate cadherin, and do not separate into distinct trachea and esophagus. These data provide new insights into the mechanisms of congenital anomalies and general paradigms of tissue fusion during organogenesis.

Clinical and molecular heterogeneity of syndromic hypothalamic hamartoma

Two children are presented who have a distinct syndrome of multiple buccolingual frenula, a stiff and short fifth finger with small nails, a hypothalamic hamartoma, mild to moderate neurological impairment, and mild endocrinological symptoms. No variant assessed to be pathogenic or likely pathogenic was detected in the GLI3 gene in either child. This syndrome appears to be distinct from the inherited Pallister-Hall syndrome associated with GLI3 variants, which is characterized by hypothalamic hamartoma, mesoaxial polydactyly, and other anomalies. In the individuals described here, manifestations outside of the central nervous system were milder and the mesoaxial polydactyly, which is common in individuals with Pallister-Hall syndrome, was absent. Instead, these children had multiple buccolingual frenula together with the unusual appearance of the fifth digit. It remains unclear whether these two individuals represent a separate nosologic entity or if they represent a milder manifestation of one of the more severe syndromes associated with a hypothalamic hamartoma.

Pallister-Hall syndrome, GLI3, and kidney malformation

Pallister-Hall syndrome (PHS) is a rare autosomal dominant disease diagnosed by the presence of hypothalamic hamartoma, mesoaxial polydactyly and a truncating variant in the middle third of the GLI-Kruppel family member 3 (GLI3) gene. PHS may also include a wide range of clinical phenotypes affecting multiple organ systems including congenital anomalies of the kidney and urinary tract (CAKUT). The observed clinical phenotypes are consistent with the essential role of GLI3, a transcriptional effector in the hedgehog (Hh) signaling pathway, in organogenesis. However, the mechanisms by which truncation of GLI3 in PHS results in such a variety of clinical phenotypes with variable severity, even within the same organ, remain unclear. In this study we focus on presentation of CAKUT in PHS. A systematic analysis of reported PHS patients (n = 78) revealed a prevalence of 26.9% (21/78) of CAKUT. Hypoplasia (± dysplasia) and agenesis were the two main types of CAKUT; bilateral and unilateral CAKUT were reported with equal frequency. Examination of clinical phenotypes with CAKUT revealed a significant association between CAKUT and craniofacial defects, bifid epiglottis and a Disorder of Sex Development, specifically affecting external genitalia. Lastly, we determined that PHS patients with CAKUT predominately had substitution type variants (as opposed to deletion type variants in non-CAKUT PHS patients) in the middle third of the GLI3 gene. These results provide a foundation for future work aimed at uncovering the molecular mechanisms by which variant GLI3 result in the wide range and severity of clinical features observed in PHS.

Pallister–Hall syndrome diagnosed in a young man after an acute adrenal crisis

Pallister–Hall syndrome (PHS) is a very rare genetic disorder. The diagnosis is usually suspected at the young age when a hypothalamic hamartoma is associated with polydactyly. Endocrine manifestations are mostly related to hypothalamic hamartoma and rarely reveal the disease. We report the case of an 18‐year‐old young man in whom the diagnosis of PHS was delayed until his hospitalization in the endocrinology department for acute adrenal insufficiency.

Disruption of Gprasp2 down-regulates Hedgehog signaling and leads to apoptosis in auditory cells

GPRASP2 is implicated in nervous system diseases, tumors and immune inflammation. In our previous study, G protein-coupled receptor associated sorting protein 2 (GPRASP2) was identified as a novel causal gene for X-linked recessive syndromic hearing loss (SHL). However, the role of GPRASP2 in auditory function has not been elucidated. The Gprasp2-knockout (KO) mouse HEI-OC1 auditory cells were constructed using CRISPR/Cas9-mediated gene editing. RNA-sequencing (RNA-seq) was used to investigate the differentially expressed genes (DEGs) and DEGs-enriched signaling pathways, which was verified by Western blot. Flow cytometry assay was used to examine cell apoptosis. The cytological pathology was evaluated by laser scanning confocal microscopy (LSCM) and transmission electron microscopy (TEM). Mitochondrial damage was observed in Gprasp2-KO HEI-OC1 cells. RNA-seq analysis suggested that Gprasp2-KO was implicated in the apoptosis process, which could be mediated by Hedgehog (Hh) signaling pathway. The key molecules in Hh signaling pathway (Smo, Gli1, Gli2) were detected to be down-regulated in Gprasp2-KO HEI-OC1 cells. The differential expression of apoptosis molecules (Bcl2, Bax, Caspase-3/cleaved-Caspase-3) indicated that Gprasp2-KO induced apoptosis in HEI-OC1 cells. The treatment of smoothened agonist (Purmorphamine, PUR) activated the Hh-Gli signaling pathway and reduced apoptosis in Gprasp2-KO HEI-OC1 cells. This study revealed that Gprasp2-disruption inhibited Hh signaling pathway and led to cell apoptosis in HEI-OC1 cells, which might provide the potential molecular mechanism of GPRASP2 mutation associated with human SHL.

Developmental basis of trachea-esophageal birth defects

Trachea-esophageal defects (TEDs), including esophageal atresia (EA), tracheoesophageal fistula (TEF), and laryngeal-tracheoesophageal clefts (LTEC), are a spectrum of life-threatening congenital anomalies in which the trachea and esophagus do not form properly. Up until recently, the developmental basis of these conditions and how the trachea and esophagus arise from a common fetal foregut was poorly understood. However, with significant advances in human genetics, organoids, and animal models, and integrating single cell genomics with high resolution imaging, we are revealing the molecular and cellular mechanisms that orchestrate tracheoesophageal morphogenesis and how disruption in these processes leads to birth defects. Here we review the current understanding of the genetic and developmental basis of TEDs. We suggest future opportunities for integrating developmental mechanisms elucidated from animals and organoids with human genetics and clinical data to gain insight into the genotype-phenotype basis of these heterogeneous birth defects. Finally, we envision how this will enhance diagnosis, improve treatment, and perhaps one day, lead to new tissue replacement therapy.

Mechanisms of larynx and vocal fold development and pathogenesis

The larynx and vocal folds sit at the crossroad between digestive and respiratory tracts and fulfill multiple functions related to breathing, protection and phonation. They develop at the head and trunk interface through a sequence of morphogenetic events that require precise temporo-spatial coordination. We are beginning to understand some of the molecular and cellular mechanisms that underlie critical processes such as specification of the laryngeal field, epithelial lamina formation and recanalization as well as the development and differentiation of mesenchymal cell populations. Nevertheless, many gaps remain in our knowledge, the filling of which is essential for understanding congenital laryngeal disorders and the evaluation and treatment approaches in human patients. This review highlights recent advances in our understanding of the laryngeal embryogenesis. Proposed genes and signaling pathways that are critical for the laryngeal development have a potential to be harnessed in the field of regenerative medicine.

Neonatal Lateral Epiglottic Defects

INTRODUCTION

Multiple congenital abnormalities of the epiglottis have been reported and iatrogenic injuries to the larynx and subglottis are well known. We present a new pattern of defect not previously reported in the literature.

METHODS

Epiglottic abnormalities at two institutions are reviewed. Cases of defects involving the lateral aspect of the epiglottis and aryepiglottic fold are identified. A literature review of known epiglottic defects is performed.

RESULTS

Two children possessing lateral notch injuries at the aryepiglottic attachment to the epiglottis are described. Both children have a history of multiple laryngeal instrumentation attempts and prolonged intubation. Both have swallowing difficulties and are gastrostomy dependent. Congenital epiglottic defects include aplasia and midline bifidity, however, no lateral congenital epiglottic defects have been reported.

CONCLUSION

Epiglottic defects, while rare, should be part of the differential for children with aspiration and feeding difficulties. A new pattern of defect is described and iatrogenic etiology proposed.

Postoperative respiratory complications and disposition in patients with type 1 laryngeal clefts undergoing injection or repair - A single institution experience

OBJECTIVE

Identify incidence and factors associated with respiratory complications after type 1 cleft repair.

METHODS

Retrospective chart review of patients who underwent cleft repair over a 5-year period performed by a single surgeon. Primary endpoint was respiratory complications (oxygen desaturation <90%). Fisher's exact test was used to identify differences between repair types (endoscopic carbon dioxide laser-assisted repair and injection laryngoplasty). Logistic regression was used to identify predictors of respiratory events.

RESULTS

Fifty-five patients were included. Thirty-four (62%) patients underwent endoscopic carbon dioxide laser-assisted repair and 21 (38%) underwent injection laryngoplasty. Average hospital stay for each group was 1.6 days (SD = 3.1) and 0.6 days (SD = 0.9), respectively. Desaturations occurred in three patients (9%) in the laser-assisted repair group and one patient (4%) in the injection group. All occurred within 3 h after surgery and resolved with supplemental oxygen, oral airway placement, and/or mask ventilation. Two affected patients had comorbid diagnosis of asthma (one had poor medication compliance), and one had a history of developmental delay and hypotonia. In the injection group, desaturations occurred in one patient with a history of tracheal stenosis and double aortic arch. No correlation existed between repair type and desaturation (p = 0.57). No variables were significant predictors of events.

CONCLUSIONS

In this cohort, respiratory events after type 1 laryngeal cleft repair occurred early in the postoperative period, in children with cardiac and pulmonary comorbidities. This suggests postoperative admission may only be necessary for a select group of patients undergoing type 1 cleft repair. However, further research is needed to determine criteria for same-day discharge.

Genetic factors in isolated and syndromic laryngeal cleft

A laryngotracheoesophageal cleft (LC) is a rare congenital anomaly of the upper aerodigestive tract resulting from the absence of fusion of the posterior cricoid lamina, which affects an abnormal communication between the larynx, trachea and esophagus. The genetic etiology of LC remains elusive. The involvement of genetic factors in the development of LC is suggested by reports of familial occurrence, and the increased prevalence of component features among first-degree relatives of affected individuals and murine knockout models. No consistent pattern of inheritance has been found in nonsyndromic patients, except for cases associated with described syndromes. Once the syndrome related to the laryngeal cleft is considered, an active search for the cleft must be initiated. The genetic evaluation of patients with LCs should be guided by the type and location of the malformation, specific medical history and a detailed physical examination. The application of genetic approaches, such as microarrays and exome sequencing might lead to elucidating the etiology of LCs.

Association of bifid epiglottis and laryngeal web with Bardet-Biedl syndrome: A case report

Bardet-Biedl syndrome (BBS) is a rare autosomal-recessive disease characterized by rod-cone dystrophy, obesity, postaxial polydactyly, cognitive impairment, hypogonadism and renal abnormalities. Bifid epiglottis and anterior laryngeal web are rare congenital anomalies and are often constituent of polymalformation syndromes. We report a case of a 9-month-old patient initially referred in otolaryngology (ENT) for dysphonia and recurrent respiratory infections. Physical exam and fiberoptic nasopharyngolaryngoscopy showed bifid epiglottis and laryngeal web associated with BBS. Those laryngeals anomalies may be underdiagnosed in BBS and this case supports the importance of upper airway evaluation by an ENT team, especially with respiratory symptoms or dysphagia.

Pallister-Hall syndrome with orofacial narrowing and tethered cord: a case report

Background

Pallister–Hall syndrome is a rare, autosomal dominant, genetic disorder characterized by different congenital abnormalities: hypothalamic hamartoblastoma, bifid or shortened epiglottis, polydactyly, renal anomalies, and imperforate anus.

Case presentation

In this case report, we describe the case of a 13-year-old Lebanese-Armenian boy born with Pallister–Hall syndrome showing newly associated manifestations (orofacial narrowing and tethered cord), and currently showing a spontaneous puberty with normal growth pattern following management with growth hormones.

Conclusions

This case report shows a practical approach to this very rare syndrome, mainly with testosterone and growth hormones, and its follow-up in the long term. Being familiar with such cases may allow improvement of our knowledge for better management in the future.

Cilia-mediated Hedgehog signaling controls form and function in the mammalian larynx

Acoustic communication is fundamental to social interactions among animals, including humans. In fact, deficits in voice impair the quality of life for a large and diverse population of patients. Understanding the molecular genetic mechanisms of development and function in the vocal apparatus is thus an important challenge with relevance both to the basic biology of animal communication and to biomedicine. However, surprisingly little is known about the developmental biology of the mammalian larynx. Here, we used genetic fate mapping to chart the embryological origins of the tissues in the mouse larynx, and we describe the developmental etiology of laryngeal defects in mice with disruptions in cilia-mediated Hedgehog signaling. In addition, we show that mild laryngeal defects correlate with changes in the acoustic structure of vocalizations. Together, these data provide key new insights into the molecular genetics of form and function in the mammalian vocal apparatus.

DOI:http://dx.doi.org/10.7554/eLife.19153.001

Nearly all animals communicate using sound. In many cases these sounds are in the form of a voice, which in mammals is generated by a specialized organ in the throat called the larynx. Millions of people throughout the world have voice defects that make it difficult for them to communicate. Such defects are distinct from speech defects such as stuttering, and instead result from an inability to control the pitch or volume of the voice. This has a huge impact because our voice is so central to our quality of life.

A wide range of human birth defects that are caused by genetic mutations are known to result in voice problems. These include disorders in which the Hedgehog signaling pathway, which allows cells to exchange information, is defective. Projections called cilia that are found on the outside of many cells transmit Hedgehog signals, and birth defects that affect the cilia (called ciliopathies) also often result in voice problems.

Although the shape of the larynx has a crucial effect on voice, relatively little is known about how it develops in embryos. Mice are often studied to investigate how human embryos develop. By studying mouse embryos that had genetic mutations similar to those seen in humans with ciliopathies, Tabler, Rigney et al. now show that many different tissues interact in complex ways to form the larynx. A specific group of cells known as the neural crest was particularly important. The neural crest helps to form the face and skull and an excess of these cells causes face and skull defects in individuals with ciliopathies. Tabler, Rigney et al. show that having too many neural crest cells can also contribute towards defects in the larynx of mice with ciliopathies, despite the larynx being in the neck.

Further investigation showed that the Hedgehog signaling pathway was required for the larynx to develop properly. Furthermore, recordings of the vocalizations of the mutant mice showed that they had defective voices, thus linking the defects in the shape of the larynx with changes in the vocalizations that the mice made.

Overall, Tabler, Rigney et al. show that mice can be used to investigate how the genes that control the shape of the larynx affect the voice. The next step will be to use mice to investigate other genetic defects that cause voice defects in humans. Further research in other animals could also help us to understand how the larynx has evolved.

DOI:http://dx.doi.org/10.7554/eLife.19153.002

Cleft Palate and Aglossia Result From Perturbations in Wnt and Hedgehog Signaling

OBJECTIVE

The objective of this study was to explore the molecular basis for cleft secondary palate and arrested tongue development caused by the loss of the intraflagellar transport protein, Kif3a.

DESIGN

Kif3a mutant embryos and their littermate controls were analyzed for defects in facial development at multiple stages of embryonic development. Histology was employed to understand the effects of Kif3a deletion on palate and tongue development. Various transgenic reporter strains were used to understand how deletion of Kif3a affected Hedgehog and Wnt signaling. Immunostaining for structural elements of the tongue and for components of the Wnt pathway were performed. BrdU activity analyses were carried out to examine how the loss of Kif3a affected cell proliferation and led to palate and tongue malformations.

RESULTS

Kif3a deletion causes cranial neural crest cells to become unresponsive to Hedgehog signals and hyper-responsive to Wnt signals. This aberrant molecular signaling causes abnormally high cell proliferation, but paradoxically outgrowths of the tongue and the palatal processes are reduced. The basis for this enigmatic effect can be traced back to a disruption in epithelial/mesenchymal signaling that governs facial development.

CONCLUSION

The primary cilium is a cell surface organelle that integrates Hh and Wnt signaling, and disruptions in the function of the primary cilium cause one of the most common-of the rarest-craniofacial birth defects observed in humans. The shared molecular basis for these dysmorphologies is an abnormally high Wnt signal simultaneous with an abnormally low Hedgehog signal. These pathways are integrated in the primary cilium.

Congenital Bilateral Saccular Cysts and Bifid Epiglottis: Presentation and Management

Saccular disorders are rare representing only 1.5 % of all laryngeal anomalies. Bifid epiglottis is also an extremely rare congenital anomaly that usually occurs in a syndromic picture in association with other anomalies such as polydactyly, cleft palate and micrognathia, which are seen in Pallister-Hall Syndrome and rarely with other syndromes. We report a case of bilateral saccular cysts and bifid epiglottis in a full term neonate presenting with stridor. The patient's other congenital anomalies included microretrognathia, short neck, polydactyly of four extremities and hypospadias. The patient underwent staged endoscopic microsurgical marsupialization of both cysts and endoscopic repair of the bifid epiglottis.

Interarytenoid Sodium Carboxymethylcellulose Gel Injection for Management of Pediatric Aspiration

Objective:

This study aimed to investigate the role of interarytenoid injection laryngoplasty (IL) for the management of pediatric aspiration.

Methods:

Medical records of 30 patients, 9 female, with radiographically confirmed chronic aspiration who underwent intraoperative IL were retrospectively reviewed. Clinical improvement was defined as successful advancement of feeds to thinner consistencies.

Results:

Clinical improvement was observed in 57% of patients. Six children with type 1 posterior laryngeal cleft (PLC-1) were not significantly more likely to show improvement compared to the children without PLC-1. Type 1 posterior laryngeal cleft was associated with older age and higher prevalence of neurodevelopmental risk factors relative to absence of PLC-1. Patients with PLC-1 were more likely than noncleft patients to show recurrence of symptoms after initial improvement with IL. Five patients underwent endoscopic repair. Repair was successful in 3 patients who improved after IL but not in 2 patients who did not improve after IL.

Conclusion:

Chronic aspiration can improve after IL even in patients with normal anatomy. Injection laryngoplasty can be performed to improve selection of PLC-1 patients for definitive endoscopic repair. Further prospective research, with a randomized control group, is needed to understand whether interarytenoid incompetence plays a role in some patients with chronic aspiration, who do not have a PLC-1.

De novo GLI3 mutation in esophageal atresia: reproducing the phenotypic spectrum of Gli3 defects in murine models

Esophageal atresia is a common and life-threatening birth defect with a poorly understood etiology. In this study, we analyzed the sequence variants of coding regions for a set of esophageal atresia-related genes including MYCN, SOX2, CHD7, GLI3, FGFR2 and PTEN for mutations using PCR-based target enrichment and next-generation sequencing in 27 patients with esophageal atresia. Genomic copy number variation analysis was performed using Affymetrix SNP 6.0. We found a de novo heterozygous mutation in the N-terminal region of the GLI3 gene (c.332T>C, p.M111T) in a patient with esophageal atresia and hemivertebrae. The N-terminal region (amino acids 1-397) of GLI3 contains the repressor domain, which interacts with SKI family proteins. Using the co-immunoprecipitation assay, we found that interaction of GLI3 with the SKI family protein SKIL was significantly compromised by the p.M111T mutation of GLI3. Thus far, all the identified mutations mapped within the repressor domain of GLI3 were nonsense and frame-shift mutations. In this study, a missense mutation was initially detected in this region. Our finding is the first to link this GLI3 gene mutation with esophageal atresia in humans, which was previously suggested in an animal model.

Mutational analysis of NOG in esophageal atresia and tracheoesophageal fistula patients

PURPOSE

The NOG protein is a secretory antagonist of bone morphogenetic proteins (BMPs). Nog-/- mouse embryos demonstrate proximal esophageal atresia (EA) and distal tracheoesophageal fistula (TEF) compatible with the most common configuration of EA/TEF observed in humans. Four microdeletions that span the NOG locus at 17q22 have been described in human patients having EA/TEF. We investigated the incidence of point mutations in the coding region of the NOG gene in human EA/TEF.

METHODS

DNA was collected from 50 patients previously treated for EA/TEF. PCR was used to amplify the coding region of NOG. To detect single nucleotide polymorphisms (SNPs), amplicons were subjected to temperature gradient capillary electrophoresis (TGCE). Candidate SNPs were directly sequenced.

RESULTS

TGCE analysis revealed a SNP in the coding region of NOG in 1 of 50 patients (2%). DNA sequencing revealed a synonymous SNP at position 468 (C-T) of the NOG coding region.

CONCLUSION

SNPs in the coding region of the NOG gene are identified infrequently in human cases of EA/TEF. Further investigation of SNPs in the promoter region of NOG is warranted, as is the effect of synonymous SNPs on NOG mRNA stability.

Bifid epiglottis: syndromic constituent rather than isolated anomaly

BACKGROUND

Bifid epiglottis is a congenital malformation defined as a midline-cleft of the epiglottis, which can be presented as an isolated anomaly as well as a part of malformation complexes. Its common occurrence in Pallister-Hall syndrome (PHS) has recently been attracting special attention. In the embryo, epiglottis, hypothalamus, and digital buds develop synchronously. Some disturbances during this stage may account for the concurrence of bifid epiglottis, hypothalamic hamartoma, and polysyndactyly in PHS. The incidence of bifid epiglottis remains unknown.

METHODS

We report here four children with bifid epiglottis out of 472 children who underwent laryngoscopy during the period from January 1995 to December 2004 in our hospital.

RESULTS

All four children presented stridor of variable degrees. One had a partial cleft of the epiglottis associated with only tracheomalacia. The other three had a complete cleft of the epiglottis associated with complex malformations: one had accessory auricles with preauricular sinus, polycystic kidney disease with intrahepatic biliary dilatation, endocardial cushion defect, and postaxial polydactyly; another had hypothalamic hamartoma, Hirschsprung disease, and polydactyly, which warranted a diagnosis of PHS; the other had no other dysmorphic features.

CONCLUSION

Bifid epiglottis can be presented as a syndromic constituent of congenital malformation syndromes rather than as an isolated anomaly. A high index of suspicion of bifid epiglottis should be raised in children with brachy-poly-syndactyly and clinical symptoms of upper airway obstruction.

Morphogenesis of the trachea and esophagus: current players and new roles for noggin and Bmps

The development of the anterior foregut of the mammalian embryo involves changes in the behavior of both the epithelial endoderm and the adjacent mesoderm. Morphogenetic processes that occur include the extrusion of midline notochord cells from the epithelial definitive endoderm, the folding of the endoderm into a foregut tube, and the subsequent separation of the foregut tube into trachea and esophagus. Defects in foregut morphogenesis underlie the constellation of human birth defects known as esophageal atresia (EA) and tracheoesophageal fistula (TEF). Here, we review what is known about the cellular events in foregut morphogenesis and the gene mutations associated with EA and TEF in mice and humans. We present new evidence that about 70% of mouse embryos homozygous null for Nog, the gene encoding noggin, a bone morphogenetic protein (Bmp) antagonist, have EA/TEF as well as defects in lung branching. This phenotype appears to correlate with abnormal morphogenesis of the notochord and defects in its separation from the definitive endoderm. The abnormalities in foregut and lung morphogenesis of Nog null mutant can be rescued by reducing the gene dose of Bmp4 by 50%. This suggests that normal foregut morphogenesis requires that the level of Bmp4 activity is carefully controlled by means of antagonists such as noggin. Several mechanisms are suggested for how Bmps normally function, including by regulating the intercellular adhesion and behavior of notochord and foregut endoderm cells. Future research must determine how Noggin/Bmp antagonism fits into the network of other factors known to regulate tracheal and esophagus development, both in mouse or humans.

What you can learn from one gene: GLI3

The study of patients with rare multiple congenital anomaly syndromes can provide illuminating insights into normal development and the pathogenesis of congenital anomalies. The GLI3 gene is a particularly good example as it illuminates the phenomena of pleiotropy, phenocopies, syndrome families, and evolutionary conservation of pathogenesis, and raises questions about how diagnoses are conceptualised. These topics are reviewed in turn, in the context of the clinical and biological data derived from patients with mutations in GLI3 and experimental work in model systems.

Laryngotracheoesophageal cleft type 3 and double outlet right ventricle: unique combination

The laryngotracheoesophageal cleft is marked by the absence of the anatomic separation of the esophagus and the larynx. The cleft functionally can be restricted to involve the interarytenoid musculature (type 1), cricoid involvement (type 2), the proximal laryngotracheoesophagus (type 3), or missing of the whole tracheoesophageal septum (type 4). Association with significant congenital heart disease is uncommon. In this report, we are presenting a 2-week-old preterm girl presented with frequent aspiration pneumonitis, cyanosis, and heart murmur. Mechanical ventilation was extremely difficult because of endotracheal tube air leak and excessive secretions. Endoscopic evaluation revealed type 3 laryngotracheoesophageal cleft. Echocardiogram revealed double outlet right ventricle with subpulmonic ventricular septal defect. Such unique combination with severe airway disease and complex congenital heart disease was thought to constitute very high morbimortality if intervention is contemplated. It was elected to proceed with compassionate care.

Genetic players in esophageal atresia and tracheoesophageal fistula

Esophageal atresia is a common and serious developmental anomaly, of which the causes remain largely unknown. Studies in vertebrate models indicate the importance of the sonic hedgehog pathway in esophageal atresia, but its relevance to the human condition remains to be defined. Now, three genes have been identified that cause syndromic forms of esophageal atresia when mutated. NMYC and SOX2 are transcription factors, whereas CHD7 is encoded by a chromodomain helicase DNA-binding gene, important for chromatin structure and gene expression. These new genes broaden our view of human foregut development.

Psychiatric and neuropsychological characterization of Pallister-Hall syndrome

Pallister-Hall syndrome (PHS) is a rare, single-gene, malformation syndrome that includes central polydactyly, hypothalamic hamartoma, bifid epiglottis, endocrine dysfunction, and other anomalies. The syndrome has variable clinical manifestations and is inherited in an autosomal dominant pattern. We sought to determine whether psychiatric disorders and/or neuropsychological impairment were characteristic of PHS. We prospectively conducted systematic neuropsychiatric evaluations with 19 PHS subjects ranging in age from 7 to 75 years. The evaluation included detailed clinical interviews, clinician-rated and self-report instruments, and a battery of neuropsychological tests. Seven of 14 adult PHS subjects met diagnostic criteria for at least one DSM-IV Axis I disorder. Three additional subjects demonstrated developmental delays and/or neuropsychological deficits on formal neuropsychological testing. However, we found no characteristic psychiatric phenotype associated with PHS, and the frequency of each of the diagnoses observed in these subjects was not different from that expected in this size sample. The overall frequency of psychiatric findings among all patients with PHS cannot be compared to point prevalence estimates of psychiatric disease in the general population because of biased ascertainment. This limitation is inherent to the study of behavioral phenotypes in rare disorders. The general issue of psychiatric evaluation of rare genetic syndromes is discussed in light of this negative result.

Significance of bifid epiglottis

Bifid epiglottis is a rare anomaly, which is heterogeneous and is often associated with other anomalies, particularly polydactyly. It has been reported in 40% of patients with Pallister-Hall syndrome and rarely in other syndromes. We report two brothers with bifid epiglottis who also have features suggestive of Bardet-Biedl syndrome. We also review the features seen in 22 patients reported in the literature with bifid epiglottis. No patient had bifid epiglottis as an isolated anomaly. Other malformations include clefts, micropenis, renal abnormalities, anal malformations, hypospadias, hypothalamic hamartomas, hypopituitarism, heart defects, and Hirschprung disease. Bifid epiglottis may be an under-recognized feature of Bardet-Biedl syndrome and should be considered in these patients, particularly if there are airway symptoms. Many of the anomalies associated with bifid epiglottis have potentially serious consequences and thus, a thorough evaluation of the patient with bifid epiglottis is warranted.

Molecular and clinical analyses of Greig cephalopolysyndactyly and Pallister-Hall syndromes: robust phenotype prediction from the type and position of GLI3 mutations

Mutations in the GLI3 zinc-finger transcription factor gene cause Greig cephalopolysyndactyly syndrome (GCPS) and Pallister-Hall syndrome (PHS), which are variable but distinct clinical entities. We hypothesized that GLI3 mutations that predict a truncated functional repressor protein cause PHS and that functional haploinsufficiency of GLI3 causes GCPS. To test these hypotheses, we screened patients with PHS and GCPS for GLI3 mutations. The patient group consisted of 135 individuals: 89 patients with GCPS and 46 patients with PHS. We detected 47 pathological mutations (among 60 probands); when these were combined with previously published mutations, two genotype-phenotype correlations were evident. First, GCPS was caused by many types of alterations, including translocations, large deletions, exonic deletions and duplications, small in-frame deletions, and missense, frameshift/nonsense, and splicing mutations. In contrast, PHS was caused only by frameshift/nonsense and splicing mutations. Second, among the frameshift/nonsense mutations, there was a clear genotype-phenotype correlation. Mutations in the first third of the gene (from open reading frame [ORF] nucleotides [nt] 1-1997) caused GCPS, and mutations in the second third of the gene (from ORF nt 1998-3481) caused primarily PHS. Surprisingly, there were 12 mutations in patients with GCPS in the 3' third of the gene (after ORF nt 3481), and no patients with PHS had mutations in this region. These results demonstrate a robust correlation of genotype and phenotype for GLI3 mutations and strongly support the hypothesis that these two allelic disorders have distinct modes of pathogenesis.

The amino-terminal region of Gli3 antagonizes the Shh response and acts in dorsoventral fate specification in the developing spinal cord

A concentration gradient of Shh is thought to pattern the ventral neural tube, and these ventral cell types are absent in shh-/- mice. Based on in vitro and genetic studies, the zinc finger-containing transcription factors Gli 1, 2, and 3 are mediators of the Shh intracellular response. The floorplate and adjacent cell types are absent in gli1-/-;gli2-/- mice, but part of the Shh-/- phenotype in the neural tube is alleviated in the Shh-/-;gli3-/- double mutant. This is consistent with the predicted role of Gli3 as a repressor of the Shh response. Gli3 repressor activity is blocked by Shh. In order to test the role of the repressor form of Gli3 in the neural tube, a truncated version of Gli3 (Gli3R*) was designed to mimic a Pallister Hall allele. Gli3R* acts as a constitutive repressor independent of Shh signaling. Misexpression of Gli3R* in the chick neural tube caused a ventral expansion of class-I, dorsal progenitor proteins and a loss of class-II, ventral progenitor proteins consistent with expected activity as a repressor of the Shh response. Activation of the BMP response is sufficient to maintain gli3 expression in neural plate explants, which might be a mechanism by which BMPs antagonize the Shh response.

Prenatal diagnosis of laryngeal atresia

Prenatal diagnosis of congenital atresia of the larynx is difficult but is possible by the findings of increased lung echogenicity and size coexisting with fetal ascites in ultrasonography. Sonographic findings may not always be typical. We report on a case of congenital laryngeal atresia diagnosed prenatally by the findings of fetal hydrops and hyperechogenic lungs. Our case presented with oligohydramnios. We also review syndromes that demonstrate laryngeal anomalies.

The VACTERL association: lessons from the Sonic hedgehog pathway

VACTERL represents a non-random association of congenital anomalies in humans of poorly known etiology and pathogenesis. From our mutant analysis of Gli genes, which encode transcription factors mediating Sonic hedgehog (Shh) signal transduction, we observed that defective Shh signaling leads to a spectrum of developmental anomalies in mice strikingly similar to those of VACTERL. In this review, we will discuss the function of the three Gli transcription factors in Shh signaling and mammalian development. We propose that VACTERL could be caused by defective Shh signaling during human embryogenesis and suggest that the Gli mutant mice can serve as useful models for studying the pathogenesis of VACTERL.