Auriculocondylar Syndrome Research Articles

Clinical evidence for a mandibular to maxillary transformation in Auriculocondylar syndrome

Clinical evidence for a mandibular to maxillary transformation in Auriculocondylar syndrome

Mutations in Endothelin 1 Cause Recessive Auriculocondylar Syndrome and Dominant Isolated Question-Mark Ears

Auriculocondylar syndrome (ACS) is a rare craniofacial disorder with mandibular hypoplasia and question-mark ears (QMEs) as major features. QMEs, consisting of a specific defect at the lobe-helix junction, can also occur as an isolated anomaly. Studies in animal models have indicated the essential role of endothelin 1 (EDN1) signaling through the endothelin receptor type A (EDNRA) in patterning the mandibular portion of the first pharyngeal arch. Mutations in the genes coding for phospholipase C, beta 4 (PLCB4) and guanine nucleotide binding protein (G protein), alpha inhibiting activity polypeptide 3 (GNAI3), predicted to function as signal transducers downstream of EDNRA, have recently been reported in ACS. By whole-exome sequencing (WES), we identified a homozygous substitution in a furin cleavage site of the EDN1 proprotein in ACS-affected siblings born to consanguineous parents. WES of two cases with vertical transmission of isolated QMEs revealed a stop mutation in EDN1 in one family and a missense substitution of a highly conserved residue in the mature EDN1 peptide in the other. Targeted sequencing of EDN1 in an ACS individual with related parents identified a fourth, homozygous mutation falling close to the site of cleavage by endothelin-converting enzyme. The different modes of inheritance suggest that the degree of residual EDN1 activity differs depending on the mutation. These findings provide further support for the hypothesis that ACS and QMEs are uniquely caused by disruption of the EDN1-EDNRA signaling pathway.

Understanding the basis of auriculocondylar syndrome: Insights from human, mouse and zebrafish genetic studies

AbstractAmong human birth defect syndromes, malformations affecting the face are perhaps the most striking due to cultural and psychological expectations of facial shape. One such syndrome is auriculocondylar syndrome (ACS), in which patients present with defects in ear and mandible development. Affected structures arise from cranial neural crest cells, a population of cells in the embryo that reside in the pharyngeal arches and give rise to most of the bone, cartilage and connective tissue of the face. Recent studies have found that most cases of ACS arise from defects in signaling molecules associated with the endothelin signaling pathway. Disruption of this signaling pathway in both mouse and zebrafish results in loss of identity of neural crest cells of the mandibular portion of the first pharyngeal arch and the subsequent repatterning of these cells, leading to homeosis of lower jaw structures into more maxillary‐like structures. These findings illustrate the importance of endothelin signaling in normal human craniofacial development and illustrate how clinical and basic science approaches can coalesce to improve our understanding of the genetic basis of human birth defect syndromes. Further, understanding the genetic basis for ACS that lies outside of known endothelin signaling components may help elucidate unknown aspects critical to the establishment of neural crest cell patterning during facial morphogenesis. © 2013 Wiley Periodicals, Inc.

Further characterization of atypical features in auriculocondylar syndrome caused by recessive PLCB4 mutations

Auriculocondylar syndrome (ACS) is a branchial arch syndrome typically inherited in an autosomal dominant fashion. Patients with ACS display the following core symptoms with varying severity: a specific malformation of the external ear, known as a "question mark ear," micrognathia and mandibular condyle hypoplasia. Recently, phospholipase C, β 4 (PLCB4) mutations were identified as the major cause of autosomal dominant ACS, with mutations of the PLCB4 catalytic domain predicted to have a dominant negative effect. In addition, one ACS patient born to related parents harbored a homozygous partial deletion of PLCB4, and presented with ACS plus central apnea and macropenis; these features had not been previously reported in association with ACS. His parents, each with a heterozygous partial PLCB4 deletion, were phenotypically normal, suggesting autosomal recessive inheritance of ACS, with complete loss of function of PLCB4 predicted in the patient. We herein describe two brothers with ACS caused by compound heterozygous splice site mutations in PLCB4. The patients were born to the same unrelated and healthy parents, with each parent harboring one of the mutations, indicating autosomal recessive ACS. Both patients reported here had mixed apneas, gastrointestinal transit defects and macropenis, in addition to typical craniofacial features of ACS. This is the first example of ACS caused by compound heterozygous splice site mutations in PLCB4, the second autosomal recessive case of ACS confirmed by molecular analysis, and strengthens the link between complete loss of function of PLCB4 and extra-craniofacial features.

Heterogeneity of mutational mechanisms and modes of inheritance in auriculocondylar syndrome

BackgroundAuriculocondylar syndrome (ACS) is a rare craniofacial disorder consisting of micrognathia, mandibular condyle hypoplasia and a specific malformation of the ear at the junction between the lobe and helix. Missense...

Ossicular fusion and cholesteatoma in auriculo‐condylar syndrome: In vivo evidence of arrest of embryogenesis

Auriculo-condylar syndrome (ACS) is a rare condition affecting first branchial arch structures. The types of hearing loss and temporal bone findings in ACS have not been reported. We describe a 14-year-old male with constricted pinnae, mandibular dysostosis, glossoptosis, a high-arched palate, hearing loss, and cholesteatoma. Computed tomography imaging demonstrated malleoincudal joint ankylosis. The fused malleoincudal complex was removed during mastoidectomy for cholesteatoma. Electron microscopy and histopathology of the joint suggested the fusion was congenital. This is the first report of ossicular fusion and cholesteatoma in ACS and the most detailed in vivo evidence of disruption of embryogenesis during malleoincudal joint formation.

A Human Homeotic Transformation Resulting from Mutations in PLCB4 and GNAI3 Causes Auriculocondylar Syndrome

Auriculocondylar syndrome (ACS) is a rare, autosomal-dominant craniofacial malformation syndrome characterized by variable micrognathia, temporomandibular joint ankylosis, cleft palate, and a characteristic "question-mark" ear malformation. Careful phenotypic characterization of severely affected probands in our cohort suggested the presence of a mandibular patterning defect resulting in a maxillary phenotype (i.e., homeotic transformation). We used exome sequencing of five probands and identified two novel (exclusive to the patient and/or family studied) missense mutations in PLCB4 and a shared mutation in GNAI3 in two unrelated probands. In confirmatory studies, three additional novel PLCB4 mutations were found in multigenerational ACS pedigrees. All mutations were confirmed by Sanger sequencing, were not present in more than 10,000 control chromosomes, and resulted in amino-acid substitutions located in highly conserved protein domains. Additionally, protein-structure modeling demonstrated that all ACS substitutions disrupt the catalytic sites of PLCB4 and GNAI3. We suggest that PLCB4 and GNAI3 are core signaling molecules of the endothelin-1-distal-less homeobox 5 and 6 (EDN1-DLX5/DLX6) pathway. Functional studies demonstrated a significant reduction in downstream DLX5 and DLX6 expression in ACS cases in assays using cultured osteoblasts from probands and controls. These results support the role of thepreviously implicated EDN1-DLX5/6 pathway in regulating mandibular specification in other species, which, when disrupted, results in a maxillary phenotype. This work defines the molecular basis of ACS as a homeotic transformation (mandible to maxilla) in humans.

The Question Mark Ear in Patients with Mandibular Hypoplasia

Sir:FigureThe question mark ear is characterized by a cleft between the lower part of the helix and the earlobe, sometimes with a prominent upper pole of the pinna, and was first described in 1961.1 The term “question mark ear” was coined in 1970.2 Ear malformations and mandibular hypoplasia can occur together in oculoauriculovertebral spectrum (Online Mendelian Inheritance in Man no. 164210) (including craniofacial microsomia and Goldenhar syndrome), Treacher Collins syndrome (Online Mendelian Inheritance in Man no. 154500), Pierre Robin sequence, and auriculocondylar syndrome (Online Mendelian Inheritance in Man no. 602483). Auricular malformations in four patients with mandibular hypoplasia were reviewed. In case 1, an 11-year-old girl presented with bilateral question mark ears and micrognathia (Fig. 1). Her mother and sister both had a unilateral question mark ear. The patient underwent bilateral mandibular distraction and later ear reconstruction.Fig. 1: Case 1. An 11-year-old girl with bilateral question mark ears and micrognathia.In case 2, a 2-year-old boy presented with a left question mark ear, Pierre Robin sequence, micrognathia, and severe obstructive sleep apnea (Fig. 2). He successfully underwent bilateral mandibular distraction osteogenesis to improve his airway.Fig. 2: Case 2. A 2-year-old boy with Pierre Robin sequence, micrognathia, and a unilateral question mark ear.In case 3, a 3-month-old boy was referred with bilateral question mark ears and severe micrognathia requiring emergency tracheostomy at birth. He had macrostomia with a trifurcated, hypoplastic tongue and gingival hypertrophy. He required bilateral hearing aids. He underwent approximately 20 operations, including mandibular distraction osteogenesis, free fibula mandibular reconstruction, release of jaw ankylosis, temporomandibular joint reconstructions, tongue Z-plasty, release of floor-of-mouth adhesions, iliac bone graft to the anterior mandible, and further bilateral mandibular distraction. In case 4, a 14-year-old boy presented with a left question mark ear and micrognathia. He underwent bilateral vertical L-osteotomies of the mandible with interpositional iliac bone grafts, bilateral coronoidectomies, and alloplastic genioplasty. The question mark ear is rare. It can arise spontaneously or by means of autosomal dominant inheritance, with high intrafamilial variability.3 The cleft associated with the question mark ear can be explained as an arrest of fusion of the fifth (helical) and sixth (lobular) hillocks.4 The reason for any accompanying mandibular or condylar hypoplasia is unknown, but both structures arise from the first pharyngeal arch. The question mark ear is thought to be a diagnostic trait for auriculocondylar syndrome, described in 1978 in a mother and two sons with bilateral external ear malformations and mandibular hypoplasia.5 Condylar hypoplasia, temporomandibular joint abnormalities, microstomia, stenotic ear canals, and hearing loss are associated. Auriculocondylar syndrome has features that overlap with other first and second pharyngeal arch disorders, especially oculoauriculovertebral spectrum. The heart, kidneys, and spine should be evaluated: auriculocondylar syndrome is thought to be similar to Goldenhar syndrome but lacks vertebral anomalies. Expression of auriculocondylar syndrome is variable. Surgery aims to reduce size and prominence of the upper pole of the ear and to correct the cleft.3 The anomaly has been classified as moderate and severe.3 Rib or contralateral conchal cartilage grafts are used to correct cartilage deficiency.4 A V-Y flap from the posterior surface of the ear can be advanced to correct the skin deficiency.4 If a notch remains, a Z-plasty can realign tissue but makes the ear smaller.4 Transposition flaps with cartilage grafts are an alternative. Ear reconstruction should be delayed until after the mandibular deficiency has been corrected, especially if there are associated respiratory problems. Aina V. H. Greig, Ph.D., F.R.C.S.(Plast.) Silvio Podda, M.D. Charles H. Thorne, M.D. Joseph G. McCarthy, M.D. Institute of Reconstructive Plastic Surgery, New York University Langone Medical Center, New York, N.Y. DISCLOSURE The authors have no financial interest to declare in relation to the content of this article. PATIENT CONSENT Parents or guardians provided written consent for the use of the patient images.

Auriculo‐condylar syndrome. Confronting a diagnostic challenge

Auriculo-condylar syndrome (ACS) is characterized by typical ears malformation (so-called "question mark" ears), prominent cheeks, microstomia, and abnormality of the temporomandibular joint and condyle of the mandible. In this report we describe a new simplex case and a previously unreported family with affected individuals in three generations documenting clinical variability. Linkage study for markers located in candidate region for ACS1 (1p21.1-q23.3) was excluded in our familial case, reinforcing the hypothesis of genetic heterogeneity for this condition. A review of the literature focusing diagnostic criteria and features of ACS was performed.

Auriculo-condylar syndrome

The auriculo-condylar syndrome is caused by abnormalities of the first and second pharyngeal arches during embryonic development. Its inheritance follows the autosomal dominant pattern. Both familial and individual cases are reported in the literature. The syndrome is characterized by wide phenotypic variation, with affected individuals expressing clinical signs of variable severity due to variable expressivity of the responsible genes. Clinical signs of the syndrome include auricular malformation, hypoplasia of the mandibular condyles, anomalies of the temporomandibular joints, malocclusion, and, in more severe cases, cleft palate, glossoptosis, facial asymmetry, and respiratory problems. The aim of this article is to report a case of a female patient with signs of the auriculo-condylar syndrome and to present the pedigree of her family. Clinical findings, diagnosis, treatment plan, and final treatment are analyzed.

Novel features in auriculo-condylar syndrome

Auriculo-condylar syndrome (ACS, OMIM 602483) is an autosomal dominant condition with marked phenotypic variability. In some patients, the condition may be limited to the auricular deformity which can vary from auricular cleft, cupped helix to the 'question mark' ear, where there is constriction between the middle and lower thirds of the ear. The latter has also been reported in isolation. Other clinical features are; facial asymmetry, round faces with prominent cheeks, microstomia, micrognathia, dental malocclusion and hearing loss. Radiological findings include abnormalities of the temporomandibular joint and/or the mandibular condyle. We describe nine ACS patients (five familial, four singleton) with novel clinical signs including facial clefts, pre-auricular and cheek pits further delineating the features of this highly variable condition. Delayed diagnosis is a common feature suggesting that ACS is largely unrecognized and may be more common than the literature suggests.

Syndromes of the first and second pharyngeal arches: A review

Our aim in this review is to discuss currently known mechanisms associated with three important syndromes of the first and second pharyngeal arches: Treacher Collins syndrome (TCS), Oculo-auriculo-vertebral syndrome (AOVS) and Auriculo-Condylar syndrome (ACS) or question mark ear syndrome. TCS and ACS are autosomal dominant diseases, with nearly complete penetrance and wide spectrum of clinical variability. The phenotype of the latter has several overlapping features with OAVS, but OAVS may exist in both sporadic and autosomal dominant forms. Mutations in the TCOF1 gene are predicted to cause premature termination codons, leading to haploinsuficiency of the protein treacle and causing TCS. Low amount of treacle leads ultimately to a reduction in the number of cranial neural crest cells migrating to the first and second pharyngeal arches. Other than TCS, the genes associated with ACS and OAVS are still unknown. The first locus for ACS was mapped by our group to 1p21-23 but there is genetic heretogeneity. Genetic heterogeneity is also present in OAVS. Based on the molecular analysis of balanced translocation in an OAVS patient, it has been suggested that abnormal expression of BAPX1 possibly due to epigenetic disregulation might be involved with the etiology of OAVS. Involvement of environmental events has also been linked to the causation of OAVS. Identification of factors leading to these disorders are important for a comprehensive delineation of the molecular pathways underlying the craniofacial development from the first and the second pharyngeal arches, for genetic counseling and to open alternative strategies for patient treatment.

Autosomal dominant isolated question mark ear

Question mark (Cosman) ear is an auricular abnormality characterized by a cleft between the lobule and the lower part of the helix, sometimes accompanied by a prominent or deficient upper part of the helix, shallow skin dimple on the posterior surface of the ear, or transposition of the ear lobe/antitragus. It can be inherited as an autosomal dominant trait. Only two families with more than one member with Question mark ear have been reported previously. Here we report on a female infant with bilateral isolated Question mark ear. The family history revealed a similar abnormality in her father and paternal grandfather. The similarity of the Question mark ear to the ear abnormalities described in auriculo-condylar syndrome (ACS) is discussed.

Evaluation of Molar Teeth and Buds in Patients Submitted to Mandible Distraction: Long-Term Results

Despite all benefits offered by mandible distraction, complications and long-term consequences need to be evaluated to define its safety and morbidity. Forty mandible distractions were studied. Panoramic mandible radiographs obtained preoperatively, during distraction, and during the postoperative period were reviewed, with the intention of evaluating development and complications of molar buds and teeth in the distraction area. The mean patient age was 8.1 years. Twenty-five patients had craniofacial microsomia (one associated with a no. 10 facial cleft), five had temporomandibular joint ankylosis, two had familiar cases of auriculocondylar syndrome, one had a Tessier no. 30 facial cleft, and one had Treacher Collins syndrome. The severity of mandible hypoplasia was Pruzansky grade I in four cases, grade IIA in eight cases, grade IIB in 16 cases, and grade III in one case. Mean radiographic follow-up was 44.8 months. Molar buds located in the distraction area erupted without any deformity or displacement in 18 sides (45 percent). Fourteen cases presented distalization of a dental bud to a superior position in the mandibular ramus (four migrated back to the original position). Six molar buds presented perforations, four had shape deformities (two caused by dental fracture), and two had dental root injuries followed by root absorption lately. One case developed a dentigerous cyst. Almost half of the patients did not have any molar bud or tooth alterations after mandible distraction, and more than 20 percent presented only bud distalization. Therefore, preventive bud enucleation or tooth extraction should be avoided before mandible distraction.

Question mark ears and post-auricular tags

Questions mark ears are an easily recognisable but uncommon malformation of the external ear. They can be found as an isolated malformation and are a pathognomonic sign of the auriculo-condylar syndrome. An additional unique sign in this syndrome may be present in the form of post-auricular tags. Such malformations should prompt further investigation for other signs of the auriculo-condylar syndrome.

Auriculo-condylar syndrome: mapping of a first locus and evidence for genetic heterogeneity

Auriculo-condylar syndrome (ACS), an autosomal dominant disorder of first and second pharyngeal arches, is characterized by malformed ears ('question mark ears'), prominent cheeks, microstomia, abnormal temporomandibular joint, and mandibular condyle hypoplasia. Penetrance seems to be complete, but there is high inter- and intra-familial phenotypic variation, with no evidence of genetic heterogeneity. We herein describe a new multigeneration family with 11 affected individuals (F1), in whom we confirm intra-familial clinical variability. Facial asymmetry, a clinical feature not highlighted in other ACS reports, was highly prevalent among the patients reported here. The gene responsible for ACS is still unknown and its identification will certainly contribute to the understanding of human craniofacial development. No chromosomal rearrangements have been associated with ACS, thus mapping and positional cloning is the best approach to identify this disease gene. To map the ACS gene, we conducted linkage analysis in two large ACS families, F1 and F2 (F2; reported elsewhere). Through segregation analysis, we first excluded three known loci associated with disorders of first and second pharyngeal arches (Treacher Collins syndrome, oculo-auriculo-vertebral spectrum, and Townes-Brocks syndrome). Next, we performed a wide genome search and we observed evidence of linkage to 1p21.1-q23.3 in F2 (LOD max 3.01 at theta=0). Interestingly, this locus was not linked to the phenotype segregating in F1. Therefore, our results led to the mapping of a first locus of ACS (ACS1) and also showed evidence for genetic heterogeneity, suggesting that there are at least two loci responsible for this phenotype.

Microtia, severe micrognathia and absent ossicles: auriculo-condylar syndrome or new entity?

The differential diagnosis of syndromes with anomalies of the first and second branchial arches includes the oculo-auriculo-vertebral syndrome, the Treacher-Collins syndrome, the acrofacial dysostoses (including Nager and Miller syndromes), the dysgnathia complex and the auriculo-condylar syndrome. Isolated microtia may also be present with involvement of other facial structures and distant organs. We report here a patient with first and second branchial arch anomalies, born to consanguineous parents. Pertinent physical findings include severe micrognathia, absence of the upper portion of the helices, atresia of the external meati and absence of the middle ear ossicles, mildly down-slanting palpebral fissures and a highly arched palate with a submucous cleft. Discussion of the differential diagnosis highlights the clinical overlap between these conditions. This constellation of findings may represent a more severe manifestation of the auriculo-condylar syndrome or a previously undescribed syndrome.

Auriculo‐condylar syndrome is associated with highly variable ear and mandibular defects in multiple kindreds

We report on 20 individuals in 4 kindreds with auriculo-condylar syndrome (ACS), an autosomal dominant disorder characterized by congenital auricular clefts, mandibular condyle hypoplasia, temporomandibular joint (TMJ) abnormalities, micrognathia, microstomia, and a round facial appearance with prominent cheeks. Affected individuals have varying degrees of glossoptosis, respiratory distress, masticatory abnormalities, and malocclusion. Data from these families and those previously described suggest that this is a unique disorder with widely variable expression, including lack of obvious external anomalies in some individuals and severe ear malformations, condyle agenesis, and characteristic facial features in others. Early recognition of this condition should permit appropriate counseling and anticipatory guidance, including evaluation for reconstructive surgery and orthodontia and intervention for upper airway obstruction and sleep apnea.

The Correction of Auricular and Mandibular Deformities in Auriculo-Condylar Syndrome

Auriculo-condylar syndrome is a rare genetic syndrome. The characteristic features of the syndrome are auricular deformity and mandibular hypoplasia. The special auricular deformity is called a question mark ear because of the appearance of the auricle. A 21-year-old male patient with auriculo-condylar syndrome is presented. The auricular deformities are treated by local flaps and anterior scoring. The mandibular contour deformity is corrected by porous polyethylene implant. Both reconstructions were successful, and patient satisfaction was good.