Two cases of agnathia (otocephaly): with review of the role of fibroblast growth factor (FGF8) and bone morphogenetic protein (BMP4) in patterning of the first branchial arch

Persistent Buccopharyngeal Membrane - A Systematic Review of Case Reports and Case Series

OBJECTIVE

Persistent buccopharyngeal membrane (PBM) is a rare anomaly associated with failure of ecto-endodermal resorption of the buccopharyngeal membrane on the 26th day of intrauterine life. The current literature has insufficient information about PBM.

DESIGN

Systematic Review.

PATIENTS, PARTICIPANTS

Online electronic databases such as PubMed-MEDLINE, Embase, and Scopus were searched using appropriate keywords from the earliest available data until 30th August 2022, with no language restriction. Additional sources such as Google Scholar, major journals, gray literature, conference proceedings, and cross-referencing were also explored.

MAIN OUTCOME MEASURES

The present systematic review evaluated and analysed the data available on PBM along with its treatment options and clinicopathological findings, prevalence, and prognosis of the patient.

RESULTS

Thirty-four publications with 37 reported cases were included in this systematic review. The majority of patients had dyspnea (n = 18), followed by dysphagia (n = 10). Approximately 16 patients suffering from PBM reported orofacial abnormalities. Seventeen patients reported complete PBM, and 18 patients had partial PBM. The treatment modality followed by most patients (n = 15) was surgical excision of the membrane, along with stent placement in four patients. Oropharyngeal reconstruction was performed in four cases. The overall prognosis and survival rate of this rare condition is good.

CONCLUSION

This review suggests that PBM is poorly understood, and the diagnosis of partial PBM is confirmed only when the patient complains of difficulty in breathing or eating. In-depth analysis and follow-up of the reported cases should be performed to diagnose the disease early so that clinicians can provide adequate treatment to the patients.

Free Fibula Flap for the Treatment of Agnathia in a 10-Year-Old With Severe Agnathia-Otocephaly Complex

Agnathia-otocephaly complex (AOC), a first branchial arch defect, is characterized by mandibular hypoplasia or aplasia, ear abnormalities, microstomia, and macroglossia and is a rare and often fatal diagnosis. Herein, the technical considerations and details of mandibular reconstruction using virtual surgical planning (VSP) and a vascularized free fibula flap for further mandibular reconstruction in a 10-year-old boy are presented. The patient's preoperative examination was consistent with agnathia (absence of mandibular symphysis, bilateral mandibular bodies, condyles, coronoids, rami, and temporomandibular joint), severe microstomia, and a Tessier # 30 cleft (maintained to allow oral access until later in treatment). Virtual surgical planning was utilized to plan a 3-segment fibula for the reconstruction of the mandibular symphysis and bilateral body segments, and bilateral costochondral grafts were planned for the rami. To the authors' knowledge, this represents the first application of virtual surgical planning for mandibular reconstruction with a vascularized free fibula flap in a pediatric patient with severe agnathia-otocephaly complex.

A case of rare isolated agnathia and literature review

Agnathia is a rare congenital malformation with unknown etiology characterized by absence of the mandible, microstomia, and tongue aplasia, often found to have other anomalies including holoprosencephaly. The purpose of this paper was to describe the symptoms and imaging of a case of isolated agnathia and to conduct a comprehensive literature review of reported patients with isolated agnathia. Case reports of isolated agnathia are very rare, with most infants as stillborn. We report a child's management of isolated agnathia with microstomia and tongue aplasia. A literature review was performed with focus on diagnosis, airway, and feeding management of isolated agnathia. Polyhydramnios was a common pregnancy complication reported in 25 out of the 39 patients in the case study. Five infants were stillborn, while 23 died within the neonatal period. Of the deceased infants within the neonatal period, 19 died within minutes to hours while four died within days to weeks. There are nine patients with agnathia that survived past infancy. The results of this study suggest that isolated agnathia is a rare malformation which requires a multi-disciplinary approach for airway and feeding management.

Roles of FGF8 subfamily in embryogenesis and oral‑maxillofacial diseases (Review)

Fibroblast growth factors (FGFs) are diffusible polypeptides released by a variety of cell types. FGF8 subfamily members regulate embryonic development processes through controlling progenitor cell growth and differentiation, and are also functional in adults in tissue repair to maintain tissue homeostasis. FGF8 family members exhibit unique binding affinities with FGF receptors and tissue distribution patterns. Increasing evidence suggests that, by regulating multiple cellular signaling pathways, alterations in the FGF8 subfamily are involved in craniofacial development, odontogenesis, tongue development and salivary gland branching morphogenesis. Aberrant FGF signaling transduction, caused by mutations as well as abnormal expression or isoform splicing, plays an important role in the development of oral diseases. Targeting FGF8 subfamily members provides a new promising strategy for the treatment of oral diseases. The aim of this review was to summarize the aberrant regulations of FGF8 subfamily members and their potential implications in oral‑maxillofacial diseases.

Haploinsufficiency of BMP4 and OTX2 in the Foetus with an abnormal facial profile detected in the first trimester of pregnancy

Background

Interstitial microdeletion 14q22q23 is a rare chromosomal syndrome associated with variable defects: microphthalmia/anophthalmia, pituitary anomalies, polydactyly/syndactyly of hands and feet, micrognathia/retrognathia. The reports of the microdeletion 14q22q23 detected in the prenatal stages are limited and the range of clinical features reveals a quite high variability.

Case presentation

We report a detection of the microdeletion 14q22.1q23.1 spanning 7,7 Mb and involving the genes BMP4 and OTX2 in the foetus by multiplex ligation-dependent probe amplification (MLPA) and verified by microarray subsequently. The pregnancy was referred to the genetic counselling for abnormal facial profile observed in the first trimester ultrasound scan and micrognathia (suspicion of Pierre Robin sequence), hypoplasia nasal bone and polydactyly in the second trimester ultrasound scan. The pregnancy was terminated on request of the parents.

Conclusion

An abnormal facial profile detected on prenatal scan can provide a clue to the presence of rare chromosomal abnormalities in the first trimester of pregnancy despite the normal result of the first trimester screening test. The patients should be provided with genetic counselling. Usage of quick and sensitive methods (MLPA, microarray) is preferable for discovering a causal aberration because some of the CNVs cannot be detected with conventional karyotyping in these cases. To the best of our knowledge, this is the earliest detection of this microdeletion (occurred de novo), the first case detected by MLPA and confirmed by microarray. Literature review of the genotype-phenotype correlation in similar reports leads us to the conclusion that dosage imbalance of the chromosomal segment 14q22q23 (especially haploinsuffiency of the genes BMP4 and OTX2) contributes significantly to orofacial abnormalities. Association of the region with the Pierre Robin sequence appears to be plausible.

Separate development of the maxilla and mandible is controlled by regional signaling of the maxillomandibular junction during avian development

BACKGROUND

Syngnathia is a congenital craniofacial disorder characterized by bony or soft tissue fusion of upper and lower jaws. Previous studies suggested some causative signals, such as Foxc1 or Bmp4, cause the disruption of maxillomandibular identity, but their location and the interactive signals involved remain unexplored. We wanted to examine the embryonic origin of syngnathia based on the assumption that it may be located at the separation between the maxillary and mandibular processes. This region, known as the maxillomandibular junction (MMJ), is involved in segregation of cranial neural crest-derived mesenchyme into the presumptive upper and lower jaws.

RESULTS

Here we investigated the role of Fgf, Bmp, and retinoid signaling during development of MMJ in chicken embryos. By changing the levels of these signals with bead implants, we induced syngnathia with microstomia on the treated side, which showed increased Barx1 and neural cell adhesion molecule (NCAM) expression. Redistribution of proliferating cells was also observed at the proximal region to maxillary and mandibular arch around MMJ.

CONCLUSIONS

We propose that interactive molecular signaling by Fgfs, Bmps, and retinoids around MMJ is required for normal separation of the maxilla and mandible, as well as the proper positioning of beak commissure during early facial morphogenesis. Developmental Dynamics 246:28-40, 2017. © 2016 Wiley Periodicals, Inc.

Severe Agnathia-Otocephaly Complex: Surgical Management and Longitudinal Follow-up From Birth Through Adulthood

Agnathia-otocephaly complex (AOC) is characterized by mandibular hypo- or aplasia, ear abnormalities, microstomia, and microglossia. Though rare and often fatal, this is the first report detailing various reconstructive strategies beyond infancy as well as longitudinal follow-up into adulthood. All patients with AOC treated at our institution over a 30 year period were reviewed. Four patients were identified, one with agnathia, one with micrognathia. Two males with nanognathia (defined as a symphyseal remnant without body nor ramus) were also included. The mean follow-up was 17 years. All four underwent perinatal tracheostomy and gastrostomy-tube placement. Commissuroplasties were typically performed before 3 years of age and repeated as necessary to allow for oral hygiene. Mandibular reconstruction was most successful with rib between ages 3 and 8, after which time, free fibula transfer was utilized. Due to some resoprtion or extrusion, all patients underwent repeated bone grafting procedures. Tissue expansion of the neck was used to restore the lower third of the face, but was most successful in the teenage years. At last follow-up of the eldest patients, one was in college while another was pursuing graduate education. AOC need not be a fatal nor untreatable condition; a reasonable quality of life can be achieved. Although the lower-facial contour may be improved, and a stoma created, the lack of musculature make deglutition virtually impossible with current therapies. Just as transplantation has emerged as a modality for facial restoration following severe trauma, so too may it be a future option for congenital deformities.

Agnathia-otocephaly complex: a case report and examination of the OTX2 and PRRX1 genes

Agnathia-otocephaly is a rare, often lethal malformation characterized by absence or hypoplasia of the mandible, microstomia, hypoglossia/aglossia, and variable anterior midline fusion of the ears (melotia, synotia). Etiologies have been linked to both genetic and teratogenic factors and to date, a definitive, commonly identifiable cause has not been recognized. Mouse and human genetic studies have implicated OTX2 and PRRX1 as potential candidate genes for agnathia-otocephaly. In this study we report a sporadic case of agnathia-otocephaly complex with associated features of maldevelopment and examine the roles of OTX2 and PRRX1. The proband, a male born at 31 weeks, displayed severe micrognathia, microstomia, posteriorly-rotated and low set ears, and downward slanting palpebral fissures. Mutation analysis was performed after sequencing the entire coding regions of OTX2 and PRRX1 genes isolated from the proband and his parents. After thorough analysis, no DNA variations were detected. This suggests that mutations in different genes or environmental causes are responsible.