Syndromes of the first and second branchial arches, part 2: syndromes

Imaging of Treacher Collins syndrome: A case report

Treacher Collins syndrome, also known as mandibulofacial dysostosis, is a rare congenital disorder affecting craniofacial development. It is caused by an autosomal dominant mutation, primarily in the TCOF1 gene, which impacts the development of the first and second branchial arches. We present the case of a 12-year-old male with bilateral conductive hearing loss and deformed ears, whose clinical and imaging findings were consistent with Treacher Collins syndrome. Imaging revealed microtia, atresia of the external auditory canals, and hypoplastic middle ear structures. Additionally, facial abnormalities such as retrognathia, hypoplastic zygomatic bones, and a cleft palate were identified. This case underscores the crucial role of imaging in diagnosing Treacher Collins syndrome and guiding multidisciplinary management strategies.

Genetic Testing in Craniofacial Care: Development of Algorithms for Testing Patients with Orofacial Clefting, Branchial Arch Anomalies, and Craniosynostosis

OBJECTIVE

To develop consensus-based algorithms for genetic testing in patients with common craniofacial conditions.

DESIGN

An online collaborative consisting of online meetings, independent work, and feedback across groups. Setting/Participants: A collaborative of genetics and pediatrics providers from three regional craniofacial centers (four institutions).

METHODS

Collaborative participants agreed upon a shared initial framework, developed algorithms independently, and presented/tested the algorithms with a national audience. Algorithms were modified based on consensus feedback.

RESULTS

The collaborative group developed final algorithms for genetic testing in patients with orofacial cleft, branchial arch conditions, and craniosynostosis.

CONCLUSIONS

Timely and accurate diagnosis of genetic conditions can support medical management recommendations that result in safer surgical interventions. Algorithms can help guide best-practices for testing, particularly in institutions without easy access to genetics providers.

Heterogeneity of Wnt1-Cre-marked and Pax2-Cre-marked first branchial arch cranial neural crest cells in mice

OBJECTIVES

This study aimed to explore the heterogeneity and gene ontology of Wnt1-Cre-marked and Pax2-Cre-marked first branchial arch cranial neural crest cells (CNCs) in mice.

METHODS

The embryos of Wnt1-Cre;R26RmTmG and Pax2-Cre;R26RmTmG at embryonic day (E)8.0-E9.25 were collected for histological observation. We performed immunostaining to compare green fluorescent protein (GFP)-positive CNCs in Pax2-Cre;R26RAi9 and Wnt1-Cre;R26RAi9 mice at E15.5. Single-cell RNA sequencing (scRNA-seq) was used to analyze the first branchial arch GFP-positive CNCs from Wnt1-Cre;R26RmTmG and Pax2-cre;R26RmTmGmice at E10.5. Real time fluorescence quantitative polymerase chain reaction (q-PCR) was performed to validate the differential genes.

RESULTS

Wnt1-Cre-marked and Pax2-Cre-marked CNCs migrated from the neural plateto first and second branchial arches and to the first branchial arch, respectively, at E8.0. Although Wnt1-Cre-marked and Pax2-Cre-marked CNCs were found mostly in cranial-facial tissues, the former had higher expression in palate and tongue. The results of scRNA-seq showed that Pax2-Cre-marked CNCs specifically contributed to osteoblast differentiation and ossification, while Wnt1-Cre-marked CNCs participated in limb development, cell migration, and ossification. The q-PCR data also confirmed the results of gene ontology analysis.

CONCLUSIONS

Pax2-Cre mice are perfect experimental animal models for research on first branchial arch CNCs and derivatives in osteoblast differentiation and ossification.

Clinical Outcomes in Orthognathic Surgery for Craniofacial Microsomia Following Mandibular Distraction Using CBCT Analysis: A Retrospective Study

OBJECTIVE

The aim of this study was to evaluate the outcomes of orthognathic surgery (OGS) in patients with craniofacial microsomia (CFM) who had previously undergone mandibular distraction osteogenesis (MDO).

DESIGN

A retrospective cohort study was performed including all patients with CFM who were treated with OGS at a single institution between 1996 and 2019. The clinical records, operative reports, and cone beam computed tomography (CBCT) scans were reviewed. CBCT data before OGS (T1), immediately after OGS (T2), and at long-term follow-up (T3) were analyzed using Dolphin three-dimensional software to measure the occlusal cant and chin point deviation.

RESULTS

The study included 12 patients with CFM who underwent OGS (6 underwent OGS without MDO and 6 underwent OGS after MDO). There was a statistically significant improvement in occlusal cant and chin point deviation in both groups postoperatively. Occlusal cant relapsed by a mean of 0.6° (standard deviation [SD] 1.1°) in the patients who had OGS alone compared with 0.7° (SD 1.2°) in the patients who had OGS after MDO (P  =  .745) between T2 and T3. There was no statistically significant difference in chin point relapse between patients who had OGS alone compared with those who had OGS after MDO (0.1 mm [SD 2.5mm] vs 0.7mm [SD 2.2mm]; P  =  .808).

CONCLUSIONS

Within the limitations of this study, these findings suggest that OGS after MDO in patients with CFM can produce stable results.

Clinical manifestations and treatment strategies for congenital aural atresia with temporomandibular joint retroposition: a retrospective study of 30 patients

BACKGROUND

Patients with congenital aural atresia (CAA) can present with concomitant temporomandibular joint (TMJ) retroposition, implying that even with a high Jahrsdoerfer score, canaloplasty and tympanoplasty cannot be performed. Therefore, this study aimed to summarize the clinical manifestations and share our diagnostic and treatment experience of this rare entity, which has not been described previously.

METHODS

Thirty patients (30 ears) with CAA and TMJ retroposition without maxillofacial dysplasia were included. Diagnosis was based on patient history, physical examination, pure-tone average test results, and temporal bone high-resolution computed tomography (HRCT) findings. Their Jahrsdoerfer scores and interventions were also recorded.

RESULTS

Twenty-four and six patients among the 30 patients (males, n = 15) had CAA and TMJ retroposition on the right and left sides, respectively. Seventeen ears had a normal auricle; most had an enlarged cavum conchae and a large tragus. Twelve ears had an accessory auricle, and two had a preauricular fistula. All external auditory canals had complete atresia, including four with a shallow concavity and four with a small orifice in the cavum conchae. Temporal bone HRCT revealed poor or undeveloped tympanic temporal bone in the diseased ears, atresia in the external auditory canals, and partial/complete occupation of the mandibular condyle with or without soft tissue. The average Jahrsdoerfer score was 8.17. Thirteen patients opted for different surgeries, three wore a bone-conduction hearing aid, and fourteen chose no intervention.

CONCLUSIONS

CAA with TMJ retroposition was often unilateral, typically on the right side. Most patients had normal auricles, with an enlarged cavum conchae and a large tragus ("mirror ear"). Even with a high Jahrsdoerfer score, traditional hearing reconstruction surgery could not be performed. Patients can undergo Vibrant Soundbridge or Bonebridge implantation or wear bone-conduction hearing aids to improve hearing levels, or refuse intervention because of mild hearing loss. The TMJ location can be used as a Jahrsdoerfer Grading System supplement for preoperative evaluation.

Congenital first branchial cleft anomalies in children: a study of 100 surgical cases and a review of the literature

OBJECTIVE

To investigate the clinical features and surgical outcomes of pediatric congenital first branchial cleft anomalies (CFBCAs).

METHODS

We conducted a retrospective analysis of 100 children who were referred to Shanghai Children's Hospital from March 2014 to March 2022 for the treatment of CFBCAs.

RESULTS

This study included 100 patients (33 males, 67 females) with an average age of 4.0 ± 2.7 years. 64 cases were type I FBCAs and 36 were type II. The main clinical manifestations included having a skin pit or discharge from it (62%), painless masses (5%), mucopurulent otorrhea (8%) and recurrent swelling with pain (90%) in the Pochet's triangle area. 92% had infection histories, 84% had incision and drainage histories, and 18% had surgical histories. 6 cases of tympanic membranous attachment were found by auricular endoscopy. Ultrasonography (US) was 55.6% (30/54) accurate and enhanced CT was 75% (75/100) accurate in diagnosing CFBCAs. We dissected the facial nerve (FN) in 46% cases. Lesions ended in the external auditory canal (EAC) wall in 86 cases. 69 exhibited close relationship with the parotid. The patients were followed up 0.25-8.2 years. 11 had postoperative temporary facial paralysis and all improved within 6 months. 3 had recurrence and they were secondarily successfully retreated. No EAC stenosis were found.

CONCLUSIONS

CFBCAs often presented with repeated swelling and purulence in Pochet's triangle. CT, US and auricular endoscopy can assist in diagnosis and planning the surgical strategy. Complete excision in non-infection stage as soon as possible is the first choice for the treatment of CFBCAs.

Extending the PAX1 spectrum: a dominantly inherited variant causes oculo-auriculo-vertebral syndrome

Oculo-auriculo-vertebral syndrome (OAVS) is a clinically heterogeneous disorder, with both genetic and environmental contributors. Multiple genes have been associated with OAVS and common molecular pathways, such as retinoic acid and the PAX-SIX-EYA-DACH (PSED) network, are being implicated in the disease pathophysiology. Biallelic homozygous nonsense or hypomorphic missense mutations in PAX1 cause otofaciocervical syndrome type 2 (OTFCS2), a similar but more severe multi-system disorder that can be accompanied by severe combined immunodeficiency due to thymic aplasia. Here we have identified a multi-generational family with mild features of OAVS segregating a heterozygous frameshift in PAX1. The four base duplication is expected to result in nonsense-mediated decay, and therefore cause a null allele. While there was full penetrance of the variant, expressivity of facial and ear features were variable. Our findings indicate there can be monoallelic and biallelic disorders associated with PAX1, and further implicate the PSED network in OAVS.

The Special Developmental Biology of Craniofacial Tissues Enables the Understanding of Oral and Maxillofacial Physiology and Diseases

Maxillofacial hard tissues have several differences compared to bones of other localizations of the human body. These could be due to the different embryological development of the jaw bones compared to the extracranial skeleton. In particular, the immigration of neuroectodermally differentiated cells of the cranial neural crest (CNC) plays an important role. These cells differ from the mesenchymal structures of the extracranial skeleton. In the ontogenesis of the jaw bones, the development via the intermediate stage of the pharyngeal arches is another special developmental feature. The aim of this review was to illustrate how the development of maxillofacial hard tissues occurs via the cranial neural crest and pharyngeal arches, and what significance this could have for relevant pathologies in maxillofacial surgery, dentistry and orthodontic therapy. The pathogenesis of various growth anomalies and certain syndromes will also be discussed.

Imaging of the Fetal Zygomatic Bone: A Key Role in Prenatal Diagnosis of First Branchial Arch Syndrome

OBJECTIVES

First arch syndromes are congenital defects caused by failure of neural crest cells to migrate into the first branchial arch. First arch syndrome is classified into 2 main clinical manifestations: Treacher Collins syndrome, characterized by bilateral underdevelopment of the zygomatic bones; and Pierre Robin sequence. The aim of this study was to describe the feasibility of visualization of the fetal zygomatic bone and assess its application in cases referred for features suggestive of first arch syndrome.

METHODS

A prospective cohort study was conducted. The feasibility of visualization of the zygomatic bone was performed in 50 sequential fetuses with a normal anatomic scan between 12 and 24 weeks' gestation using 3-dimensional sonography. Following this, cases referred for targeted scans for suspected first branchial arch syndrome were assessed for the presence or absence of the zygomatic bones.

RESULTS

Visualization of the fetal zygomatic bone was feasible in all low-risk cases. Cases referred for targeted scans included 11 isolated cases of micrognathia or retrognathia, 3 cases of microtia, and 3 cases of auricular or facial vestiges. Within this group, the zygomatic bones were visualized in all but 2 cases. No associated extrafacial malformations were detected; therefore, this phenotype was consistent with Treacher Collins syndrome.

CONCLUSIONS

Prenatal imaging of the zygomatic bones offers a clinically based sonographic approach to cases referred for features suggestive of first arch syndrome and enables differentiation between the 2 main clinical manifestations: Treacher Collins syndrome and Pierre Robin sequence.

Comparison Between Treacher Collins Syndrome and Pierre Robin Sequence: A Cephalometric Study

OBJECTIVE

The aim of this study was to compare the dentoskeletal pattern of Treacher Collins syndrome (TCS) and nonsyndromic Pierre Robin sequence (PRS).

DESIGN

Retrospective.

SETTING

Single center.

PATIENTS

Eighteen patients diagnosed with TCS (Group TCS) or PRS (Group PRS) in rehabilitation treatment at a single center. Group TCS was composed of 9 patients (4 male, 5 female) with a mean age of 12.9 years (standard deviation = 4.8). Group PRS was composed of 9 patients paired by age and sex with group TCS.

MAIN OUTCOME MEASURE(S)

Cone beam computed tomography-derived cephalometric images taken before the orthodontic or the orthodontic-surgical treatment were analyzed using Dolphin Imaging (Dolphin Imaging 11.0 & Management Solutions). Variables evaluating the cranial base, the maxillary and mandibular skeletal components, maxillomandibular relationship, the vertical components and the dentoalveolar region were measured. Intergroup comparisons were performed using t tests. The significance level considered was 5%.

RESULTS

Intergroup differences in the mandible size and growth pattern were observed. Group TCS showed a smaller mandibular length (Co-Go, Co-Gn) and a higher palatal plane (SN-Palatal Plane) and mandibular plane angles (SN-Go.Gn) compared to group PRS. No differences between TCS and PRS were observed for the sagittal position of the maxilla, maxillomandibular relationship, and dental components.

CONCLUSIONS

Treacher Collins syndrome presented a decreased mandible and a more severe vertical growth pattern compared to PRS.

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.

Chromosomal microarray analysis in the prenatal diagnosis of orofacial clefts: Experience from a single medical center in mainland China

The aim of this study was to investigate the value of chromosomal microarray analysis (CMA) for the prenatal diagnosis of orofacial clefts.A total of 143 fetuses with oral clefts were detected by ultrasound during prenatal exam between 2012 and 2017 in our center. We categorized the cases into 4 groups: isolated cleft lip (CL) (CL only), isolated cleft palate (CP only), isolated cleft lip and palate (CLP) (CLP only), and syndromic CLP (combined with other malformations). The CMA was performed in all cases, while 139 fetuses were referred for G-banded chromosome analysis.There were 42 male and 10 female fetuses were born, with a sex ratio of 4.2:1. The isolated CLP group accounted for 74.1% (106/143) of cases, while the isolated CL, isolated CP, and syndromic CP groups accounted for 13.9% (20/143), 2% (3/143), and 10% (14/143), respectively. A total of 11 fetuses had pathogenic copy number variants (CNVs, 7.7%), including isolated CP (1/143, 0.7%), isolated CLP (5/143, 3.5%), and syndromic CLP (5/143, 3.5%). Compared with the CMA results, 5 fetuses were found to have an abnormal karyotype (5/139, 3.6%). However, no abnormalities were found in either karyotype analysis or CMA in the isolated CL group.CMA is a valuable tool for identifying submicroscopic chromosomal abnormalities in the prenatal diagnosis of oral clefts. An excellent outcome can be expected for fetuses with isolated CL that are negative for chromosomal abnormalities.

Oculoauriculovertebral spectrum and maxillary sinus volumes : CT-based comparative evaluation

OBJECTIVES

To evaluate, by comparing maxillary sinus volumes, how asymmetries related to oculoauriculovertebral spectrum (OAVS) affect upper-jaw development.

METHODS

From pre-existing multislice spiral computed tomography (MSCT) datasets, we selected 20 cases of 11 female and 9 male patients aged 6.1-24 years who were clinically and radiographically symmetrical (group 1) plus 20 cases of 8 female and 12 male patients aged 5.7-23.9 years who had OAVS (group 2). After three-dimensional reconstruction of the datasets, the volumes of the left and right maxillary sinuses were calculated and compared based on patient groups and based on the sides affected or unaffected by OAVS. To this end, the OAVS patients were subdivided into a group in whom both external acoustic pores were radiographically present (group 2a) and a group in whom the pore on the affected side was congenitally missing (group 2b).

RESULTS

Intrarater reliability was very high (0.997). Significantly larger volumes of the maxillary sinuses, amounting to a mean of 13.4 ml, were observed in the control group than in the asymmetric OAVS groups where the volumes averaged 9.8 ml or 10.3 ml, respectively (p = 0.03). No statistically significant differences in sinus volumes were found between the two OAVS groups (p = 0.557) and between the sides affected or unaffected by the OAVS (p = 0.8311 in group 2a and 0.4961 in group 2b).

CONCLUSIONS

Overall, we found the volumes of both maxillary sinuses to be somewhat smaller in the asymmetric patients than in the symmetric control group. This might indicate that OAVS was associated with a mild generalized hypoplasia of the maxilla, but significantly different sinus volumes were not seen between the affected and unaffected sides.

Clinical and cytogenomic findings in OAV spectrum

The oculoauriculovertebral spectrum (OAVS) is characterized by anomalies involving the development of the first and second pharyngeal arches during the embryonic period. The phenotype is highly heterogeneous, involving ears, eyes, face, neck, and other systems and organs. There is no agreement in the literature for the minimum phenotypic inclusion criteria, but the primary phenotype involves hemifacial microsomia with facial asymmetry and microtia. Most cases are sporadic and the etiology of this syndrome is not well known. Environmental factors, family cases that demonstrate Mendelian inheritance, such as preauricular appendages, microtia, mandibular hypoplasia, and facial asymmetry; chromosomal abnormalities and some candidate genes suggest a multifactorial inheritance model. We evaluated clinical, cytogenomic and molecularly 72 patients with OAVS, and compared our findings with patients from the literature. We found 15 CNVs (copy number variations) considered pathogenic or possibly pathogenic in 13 out of 72 patients. Our results did not indicated a single candidate genomic region, but recurrent chromosomal imbalances were observed in chromosome 4 and 22, in regions containing genes relevant to the OAVS phenotype or related to known OMIM diseases suggesting different pathogenic mechanisms involved in this genetically and phenotypic heterogeneous spectrum.

Low-set ears and associated anomalies in human foetuses

OBJECTIVES

To determine the prevalence of low-set ears (LSE) in a group of human foetuses, to analyse the associated anomalies, and to review the development mechanisms possibly involved.

METHODS

A total of 1759 human foetuses from spontaneous abortion were evaluated. Foetuses were obtained from the Foetuses and Embryos Collection of the Embryology Department of the Faculty of Medicine of the Autonomous University of Nuevo León. The Ethics Committee gave its approval for this study (EH-230-16). The position of the auricles was determined according to the standards recommended by the Elements of Morphology. Two study groups were created: foetuses with LSE and foetuses with normal ears. In both groups, a detailed examination of the external morphology was performed, followed by thoraco-abdominal micro dissection. Statistical analysis was performed.

RESULTS

Two hundred two of the foetuses presented LSE (1148 per 10,000). In this group, 68.8% did not present associated anomalies, while 31.2% had an associated anomaly. The most frequently affected organ was the heart (53.6%), followed by the digestive tract (23.9%), urinary system (16.9%), head and neck (4.2%), and limbs (1.4%). In the group of foetuses with normal ears, only 7.4% of the specimens had associated anomalies, which was a significant difference compared with the LSE group.

CONCLUSIONS

Based on the obtained results, we consider that LSE can be used as a sensitive indicator of major anomalies. It is recommended to include a systematic assessment of the position of the auricles in the initial clinical evaluation of any newborn.

Targeted molecular investigation in patients within the clinical spectrum of Auriculocondylar syndrome

Auriculocondylar syndrome, mainly characterized by micrognathia, small mandibular condyle, and question mark ears, is a rare disease segregating in an autosomal dominant pattern in the majority of the families reported in the literature. So far, pathogenic variants in PLCB4, GNAI3, and EDN1 have been associated with this syndrome. It is caused by a developmental abnormality of the first and second pharyngeal arches and it is associated with great inter- and intra-familial clinical variability, with some patients not presenting the typical phenotype of the syndrome. Moreover, only a few patients of each molecular subtype of Auriculocondylar syndrome have been reported and sequenced. Therefore, the spectrum of clinical and genetic variability is still not defined. In order to address these questions, we searched for alterations in PLCB4, GNAI3, and EDN1 in patients with typical Auriculocondylar syndrome (n = 3), Pierre Robin sequence-plus (n = 3), micrognathia with additional craniofacial malformations (n = 4), or non-specific auricular dysplasia (n = 1), which could represent subtypes of Auriculocondylar syndrome. We found novel pathogenic variants in PLCB4 only in two of three index patients with typical Auriculocondylar syndrome. We also performed a detailed comparative analysis of the patients presented in this study with those previously published, which showed that the pattern of auricular abnormality and full cheeks were associated with molecularly characterized individuals with Auriculocondylar syndrome. Finally, our data contribute to a better definition of a set of parameters for clinical classification that may be used as a guidance for geneticists ordering molecular testing for Auriculocondylar syndrome. © 2017 Wiley Periodicals, Inc.

Three-dimensional assessment of the temporal bone and mandible deformations in patients with congenital aural atresia

OBJECTIVE

To investigate the deformations of temporal bone and mandible combined with congenital aural atresia.

METHODS

A total of 158 patients with congenital aural atresia were included in the study. The raw CT data of the temporal bone was imported into MIMICS v 12 and threshold dissection, region growing and three-dimensional (3D) calculation were used to calculate 3D models. The 3D characteristics of the temporal bone and upper part of mandible were assessed.

RESULTS

The tympanic part of the temporal bone was all undeveloped. Of all the patients included, 14 patients were found to have severe maxillofacial malformations. Among them, 2 cases have floating arch, 4 cases have interrupted arch, 5 cases have mandibular processes hypoplasia and 3 cases have interrupted arch combined with severe maxillary malformation. Ten of the 14 patients were suffered from dysplasia of the mastoid part of the temporal bone as well.

CONCLUSION

Maxillofacial malformations may sometimes coexist with congenital aural atresia. Otolaryngologists should not neglect the coexisted maxillofacial malformations and give timely referral to maxillofacial surgeons.

Diagnosis of fetal syndromes by three- and four-dimensional ultrasound: is there any improvement?

With all of our present knowledge, high technology diagnostic equipment, electronic databases and other available supporting resources, detection of fetal syndromes is still a challenge for healthcare providers in prenatal as well as in the postnatal period. Prenatal diagnosis of fetal syndromes is not straightforward, and it is a difficult puzzle that needs to be assembled and solved. Detection of one anomaly should always raise a suspicion of the existence of more anomalies, and can be a trigger to investigate further and raise awareness of possible syndromes. Highly specialized software systems for three- and four-dimensional ultrasound (3D/4D US) enabled detailed depiction of fetal anatomy and assessment of the dynamics of fetal structural and functional development in real time. With recent advances in 3D/4D US technology, antenatal diagnosis of fetal anomalies and syndromes shifted from the 2nd to the 1st trimester of pregnancy. It is questionable what can and should be done after the prenatal diagnosis of fetal syndrome. The 3D and 4D US techniques improved detection accuracy of fetal abnormalities and syndromes from early pregnancy onwards. It is not easy to make prenatal diagnosis of fetal syndromes, so tools which help like online integrated databases are needed to increase diagnostic precision. The aim of this paper is to present the possibilities of different US techniques in the detection of some fetal syndromes prenatally.

The Role of Sonic Hedgehog in Craniofacial Patterning, Morphogenesis and Cranial Neural Crest Survival

Craniofacial defects (CFD) are a significant healthcare problem worldwide. Understanding both the morphogenetic movements which underpin normal facial development, as well as the molecular factors which regulate these processes, forms the cornerstone of future diagnostic, and ultimately, preventative therapies. The soluble morphogen Sonic hedgehog (Shh), a vertebrate orthologue of Drosophila hedgehog, is a key signalling factor in the regulation of craniofacial skeleton development in vertebrates, operating within numerous tissue types in the craniofacial primordia to spatiotemporally regulate the formation of the face and jaws. This review will provide an overview of normal craniofacial skeleton development, and focus specifically on the known roles of Shh in regulating the development and progression of the first pharyngeal arch, which in turn gives rise to both the upper jaw (maxilla) and lower jaw (mandible).

Respiratory and gastrointestinal dysfunctions associated with auriculo-condylar syndrome and a homozygous PLCB4 loss-of-function mutation

Auriculo-Condylar Syndrome (ACS) is a craniofacial malformation syndrome characterized by external ear anomalies, hypoplasia of the mandibular condyle, temporomandibular joint abnormalities, micrognathia, and microstomia. Glossoptosis, masticatory abnormalities, orthodontic problems, and malocclusion occur in a majority of affected subjects. The clinical diagnosis is usually suggested by the pathognomonic ear appearance ("question mark ear"), consisting of a variable degree of clefting between the helix and earlobe. The genetic mechanisms underlying ACS have recently been identified. Both autosomal dominant and recessive inheritance of mutations in phospholipase C, beta 4 (PLCB4) and endothelin 1 (EDN1) have been reported along with autosomal dominant mutations in guanine nucleotide-binding protein (G protein) α inhibiting activity polypeptide 3 (GNAI3). We report 6 years of follow-up of a child with a clinical phenotype consistent with ACS due to a homozygous frameshift mutation in PLCB4. The baby presented feeding difficulties associated with failure to thrive and a complex sleep-related respiratory disorder, characterized by central and obstructive apnoeas. Our observations of this case further delineate the phenotype of ACS associated with autosomal recessive PLCB4 loss-of-function mutations, underscoring gastrointestinal dysfunction and severe sleep-related breathing abnormalities as additional features when compared to patients with heterozygous mutations with a presumed dominant negative effect. © 2016 Wiley Periodicals, Inc.

Early Detection of Cleft Lip by Three-Dimensional Transvaginal Ultrasound in Niche Mode in a Fetus With Trisomy 18 Diagnosed by Celocentesis

Transabdominal ultrasound examination carried out at 11.3 weeks' gestation suggested the diagnosis of holoprosencephaly (HPE). Transvaginal three-dimensional (3D) scan performed using the niche-mode technique enabled diagnosis of HPE, hypotelorism, and cleft lip (CL). The fetus was diagnosed with trisomy 18 by means of transvaginal celocentesis at the time of pregnancy termination. Although prenatal diagnosis of orofacial cleft can be enhanced by 3D ultrasound, only a few cases have been detected early in pregnancy. Here, we report a first-trimester case in which 3D ultrasound in niche mode improved the antenatal diagnosis of CL. Early fetal karyotyping can be accomplished by celocentesis in these cases.

Imaging neonates and children with Pierre Robin sequence before and after mandibular distraction osteogenesis: what the craniofacial surgeon wants to know

Pierre Robin sequence is characterized by micrognathia and glossoptosis causing upper airway obstruction. Mandibular distraction osteogenesis is a mandibular lengthening procedure performed in neonates and children with Pierre Robin sequence to alleviate airway compromise. This pictorial review demonstrates the role of imaging in the preoperative and postoperative assessment of these children. It is important for pediatric radiologists to know what information about the mandible and airway the craniofacial surgeon needs from preoperative imaging and to identify any complications these children may encounter after surgery.

Role of Imaging and Cytogenetics in Evaluation of DiGeorge Syndrome - A Rare Entity in Clinical Practice

DiGeorge syndrome is a congenital genetic disorder that affects the endocrine system, mainly the thymus and parathyroid glands. The syndrome produces different symptoms, which vary in severity and character between patients. It manifests with craniofacial dysmorphism and defects in the heart, parathyroid, and thymus. Patients can present with a palatal deformity and nasal speech. This rare entity is caused mainly due to deletion of chromosome 22q11.2. Radiographic evaluation of DiGeorge syndrome is necessary to define aberrant anatomy, evaluate central nervous system, craniofacial abnormalities, musculoskeletal system, and cardiothoracic contents. It also helps in planning surgical procedures and surgical reconstructions. We report a case of DiGeorge syndrome in a 4-month-old neonate and discuss the clinical, imaging, and cytogenetic findings that helped in the diagnosis of this rare entity.

Anteverted internal auditory canal as an inner ear anomaly in patients with craniofacial microsomia

Craniofacial microsomia involves structure of the first and second branchial arches. A wide range of ear anomalies, affecting external, middle and inner ear, has been described in association with this condition. We report three cases of anteverted internal auditory canal in patients presenting craniofacial microsomia. This unique internal auditory canal orientation was found on high-resolution computed tomography of the temporal bones. This internal auditory canal anomaly is yet unreported in craniofacial anomalies.

A LINE-1 insertion in DLX6 is responsible for cleft palate and mandibular abnormalities in a canine model of Pierre Robin sequence

Cleft palate (CP) is one of the most commonly occurring craniofacial birth defects in humans. In order to study cleft palate in a naturally occurring model system, we utilized the Nova Scotia Duck Tolling Retriever (NSDTR) dog breed. Micro-computed tomography analysis of CP NSDTR craniofacial structures revealed that these dogs exhibit defects similar to those observed in a recognizable subgroup of humans with CP: Pierre Robin Sequence (PRS). We refer to this phenotype in NSDTRs as CP1. Individuals with PRS have a triad of birth defects: shortened mandible, posteriorly placed tongue, and cleft palate. A genome-wide association study in 14 CP NSDTRs and 72 unaffected NSDTRs identified a significantly associated region on canine chromosome 14 (24.2 Mb–29.3 Mb; p_raw = 4.64×10⁻¹⁵). Sequencing of two regional candidate homeobox genes in NSDTRs, distal-less homeobox 5 (DLX5) and distal-less homeobox 6 (DLX6), identified a 2.1 kb LINE-1 insertion within DLX6 in CP1 NSDTRs. The LINE-1 insertion is predicted to insert a premature stop codon within the homeodomain of DLX6. This prompted the sequencing of DLX5 and DLX6 in a human cohort with CP, where a missense mutation within the highly conserved DLX5 homeobox of a patient with PRS was identified. This suggests the involvement of DLX5 in the development of PRS. These results demonstrate the power of the canine animal model as a genetically tractable approach to understanding naturally occurring craniofacial birth defects in humans.

Cleft palate is one of the most commonly occurring birth defects in children, and yet its cause is not completely understood. In order to better understand cleft palate we have turned to man's best friend, the domestic dog. Common breeding practices have made the dog a unique animal model to help understand the genetic basis of naturally occurring birth defects. A genome-wide association study of Nova Scotia Duck Tolling Retrievers with naturally occurring cleft palate led to the investigation of two homeobox genes, DLX5 and DLX6. Dogs with this mutation also have a shortened lower jaw, which resembles those who have Pierre Robin Sequence (PRS). Investigation into people with PRS identifies a mutation within a highly conserved and functional region of DLX5 that may contribute to the development of PRS. This exemplifies how the dog will help us better understand common birth defects.

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

Among 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.

Loss of function of the E3 ubiquitin-protein ligase UBE3B causes Kaufman oculocerebrofacial syndrome

Background

Kaufman oculocerebrofacial syndrome (KOS) is a developmental disorder characterised by reduced growth, microcephaly, ocular anomalies (microcornea, strabismus, myopia, and pale optic disk), distinctive facial features (narrow palpebral fissures, telecanthus, sparse and laterally broad eyebrows, preauricular tags, and micrognathia), mental retardation, and generalised hypotonia. KOS is a rare, possibly underestimated condition, with fewer than 10 cases reported to date. Here we investigate the molecular cause underlying KOS.

Methods

An exome sequencing approach was used on a single affected individual of an Italian consanguineous family coupled with mutation scanning using Sanger sequencing on a second unrelated subject with clinical features fitting the disorder.

Results

Exome sequencing was able to identify homozygosity for a novel truncating mutation (c.556C>T, p.Arg186stop) in UBE3B, which encodes a widely expressed HECT (homologous to the E6-AP carboxyl terminus) domain E3 ubiquitin-protein ligase. Homozygosity for a different nonsense lesion affecting the gene (c.1166G>A, p.Trp389stop) was documented in the second affected subject, supporting the recessive mode of inheritance of the disorder. Mutation scanning of the entire UBE3B coding sequence on a selected cohort of subjects with features overlapping, in part, those recurring in KOS did not reveal disease-causing mutations, suggesting phenotypic homogeneity of UBE3B lesions.

Discussion

Our data provide evidence that KOS is caused by UBE3B loss of function, and further demonstrate the impact of misregulation of protein ubiquitination on development and growth. The available clinical records, including those referring to four UBE3B mutation-positive subjects recently described as belonging to a previously unreported entity, which fits KOS, document the clinical homogeneity of this disorder.

Coexistence of bilateral first and second branchial arch anomalies

Branchial arch anomalies are one of the most common congenital anomalies that are usually unilateral and bilateral presentation is rare. The simultaneous presence of bilateral second branchial arch anomalies along with bilateral first arch anomalies is extremely rare, with only three such cases reported in the literature. We present two non-syndromic cases of coexisting bilateral first and second arch anomalies. Developmental anomalies of the branchial apparatus account for 17% of all paediatric cervical masses and are the most common type of congenital cervical mass. They usually present in the paediatric age group. About 96-97% of these anomalies are unilateral. Bilateral presentation is seen in 2-3% having a strong familial association. Congenital syndromes also have been associated with first and second branchial arch anomalies. Thorough clinical examination and investigations should be done to rule out these syndromes.

Prenatal diagnosis of treacher-collins syndrome using three-dimensional ultrasonography and differential diagnosis with other acrofacial dysostosis syndromes

Treacher-Collins syndrome (TCS) is a rare dominant autosomal anomaly resulting from malformation or disruption of the development of the first and second branchial arches. It is characterized by micrognathia, malar hypoplasia, and malformations of the eyes and ears. The prenatal diagnosis using two-dimensional ultrasonography (2DUS) is characterized by identification of facial malformations together with polyhydramnios. Three-dimensional ultrasonography (3DUS) has the capacity to spatially display these facial malformations, thus making it easy for the parents to understand them. We present a case of TCS diagnosed in the 33rd week using 3DUS, with postnatal confirmation using cranial computed tomography and anatomopathological analysis.

Elongation factor 1 alpha1 and genes associated with Usher syndromes are downstream targets of GBX2

Gbx2 encodes a DNA-binding transcription factor that plays pivotal roles during embryogenesis. Gain-and loss-of-function studies in several vertebrate species have demonstrated a requirement for Gbx2 in development of the anterior hindbrain, spinal cord, inner ear, heart, and neural crest cells. However, the target genes through which GBX2 exerts its effects remain obscure. Using chromatin immunoprecipitation coupled with direct sequencing (ChIP-Seq) analysis in a human prostate cancer cell line, we identified cis-regulatory elements bound by GBX2 to provide insight into its direct downstream targets. The analysis revealed more than 286 highly significant candidate target genes, falling into various functional groups, of which 51% are expressed in the nervous system. Several of the top candidate genes include EEF1A1, ROBO1, PLXNA4, SLIT3, NRP1, and NOTCH2, as well as genes associated with the Usher syndrome, PCDH15 and USH2A, and are plausible candidates contributing to the developmental defects in Gbx2(-/-) mice. We show through gel shift analyses that sequences within the promoter or introns of EEF1A1, ROBO1, PCDH15, USH2A and NOTCH2, are directly bound by GBX2. Consistent with these in vitro results, analyses of Gbx2(-/-) embryos indicate that Gbx2 function is required for migration of Robo1-expressing neural crest cells out of the hindbrain. Furthermore, we show that GBX2 activates transcriptional activity through the promoter of EEF1A1, suggesting that GBX2 could also regulate gene expression indirectly via EEF1A. Taken together, our studies show that GBX2 plays a dynamic role in development and diseases.

Developmental maxillofacial anomalies

There is a wide variety of developmental maxillofacial anomalies secondary to defective transformation of the first pair of pharyngeal arches into adult structures. Computed tomography and magnetic resonance imaging are essential to precisely define aberrant maxillofacial anatomy and guide appropriate management. This review article provides an overview of maxillofacial embryogenesis, clinical symptoms, and characteristic imaging features of several anomalies, including choanal atresia, congenital nasal piriform aperture stenosis, dacryocystoceles, nasolacrimal duct stenosis, cleft lip and palate, micrognathia, and midline nasal masses. Finally the major features of common first pharyngeal arch syndromes are discussed.