Otocephaly: report of five new cases and a literature review

Otocephaly: A Case Report of a Rare Congenital Anomaly

Otocephaly is a rare congenital abnormality characterized by the absence or underdevelopment of the mandible, misplacement of the ears towards the front, a small mouth, and absence or underdevelopment of the tongue. The syndrome complex of otocephaly can be categorized into four types based on associated anomalies. We present a case of this congenital anomaly in a newborn baby delivered by a 40-year-old woman who presented in active labor with premature rupture of membranes. Unfortunately, the newborn did not survive due to severe respiratory distress, which was consistent with the clinical features of this congenital anomaly. The rarity of otocephaly poses challenges for both parents and healthcare providers. Early antenatal scans are suggested for the early diagnosis of this condition. Further research and awareness are needed to better understand and manage this rare congenital disorder.

DLX6 and MSX1 from saliva samples as potential predictors of mandibular size: A cross-sectional study

INTRODUCTION

Morphologic features of the mandible are influenced by the genes of each individual. Mandible size is important to orthodontists because the mandible is the mechanism by which the lower face influences facial esthetics and dental function. To date, no biological marker has been identified that indicates eventual mandible size. This study aimed to correlate the expression of DLX5, DLX6, EDN1, HAND2, PRRX1, and MSX1 to mandible size.

METHODS

Fifty-nine orthodontic patients aged >6 years who had available cephalometric radiographs were studied. Patients were classified on the basis of condylion-to-gnathion measurements. Messenger RNA was isolated from saliva and subjected to real-time quantitative polymerase chain reaction.

RESULTS

Threshold cycle values for subjects with small mandibles (>1 standard deviation [SD] from the mean) had the least expression of DLX6 and MSX1. Threshold cycle values for subjects with large mandibles (>1 SD) had less expression of DLX6 and MSX1 than subjects within 1 SD but more than those with small mandibles.

CONCLUSIONS

DLX6 and MSX1 are related to mandible development and size. This finding could be used to improve treatment planning for medical and dental professionals seeking to understand the impact of genetics on bone growth.

Agnathia-Otocephaly Complex Due to a De Novo Deletion in the OTX2 Gene

Agnathia-otocephaly complex (AOC) is a rare and usually lethal malformation typically characterized by hypoplasia or the absence of the mandible, ventromedial and caudal displacement of the ears with or without the fusion of the ears, a small oral aperture with or without a tongue hypoplasia. Its incidence is reported as 1 in 70,000 births and its etiology has been attributed to both genetic and teratogenic causes. AOC is characterized by a wide severity clinical spectrum even when occurring within the same family, ranging from a mild mandibular defect to an extreme facial aberration incompatible with life. Most AOC cases are due to a de novo sporadic mutation. Given the genetic heterogeneity, many genes have been reported to be implicated in this disease but to date, the link to only two genes has been confirmed in the development of this complex: the orthodenticle homeobox 2 (OTX2) gene and the paired related homeobox 1 (PRRX1) gene. In this article, we report a case of a fetus with severe AOC, diagnosed in routine ultrasound scan in the first trimester of pregnancy. The genetic analysis showed a novel 10 bp deletion mutation c.766_775delTTGGGTTTTA in the OTX2 gene, which has never been reported before, together with a missense variant c.778T>C in cis conformation.

Gangliosides as Biomarkers of Human Brain Diseases: Trends in Discovery and Characterization by High-Performance Mass Spectrometry

Gangliosides are effective biochemical markers of brain pathologies, being also in the focus of research as potential therapeutic targets. Accurate brain ganglioside mapping is an essential requirement for correlating the specificity of their composition with a certain pathological state and establishing a well-defined set of biomarkers. Among all bioanalytical methods conceived for this purpose, mass spectrometry (MS) has developed into one of the most valuable, due to the wealth and consistency of structural information provided. In this context, the present article reviews the achievements of MS in discovery and structural analysis of gangliosides associated with severe brain pathologies. The first part is dedicated to the contributions of MS in the assessment of ganglioside composition and role in the specific neurodegenerative disorders: Alzheimer’s and Parkinson’s diseases. A large subsequent section is devoted to cephalic disorders (CD), with an emphasis on the MS of gangliosides in anencephaly, the most common and severe disease in the CD spectrum. The last part is focused on the major accomplishments of MS-based methods in the discovery of ganglioside species, which are associated with primary and secondary brain tumors and may either facilitate an early diagnosis or represent target molecules for immunotherapy oriented against brain cancers.

Agnathia-otocephaly complex diagnosed by prenatal ultrasound: a case report

Agnathia-otocephaly complex (AOC) is a rare and complex craniofacial malformation characterized by mandibular hypoplasia or agnathia, auricular fusion (synotia), and microstomia with oroglossal hypoplasia or aglossia. It can occur alone or in combination with forebrain anomalies and cardiac malformations and has an extremely poor prognosis. Here, we report a case of AOC diagnosed by systemic fetal screening at a gestational age of 25⁺⁴ weeks. Ultrasound revealed that the S-curve formed by the normal lower jaw and lower lip had disappeared, the lower jaw and mandible were invisible, the mouth was extremely small, and the oral fissure was "pinhole-shaped". There was a cone-shaped perioral bulge. Both ears were located in the front side of the neck, and the right foot was inverted. Excessive amniotic fluid was observed. The absence of a mandible was confirmed on X-ray examination after induced abortion. Specimen observation showed that the ear positions were extremely low, and both earlobes were connected in the front side of the neck. It was particularly challenging to identify the development of the mandible and locate auricles during prenatal ultrasound diagnosis, and the prenatal diagnosis of AOC was confirmed by combining two-dimensional and three-dimensional ultrasound in our current case.

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.

Re-focusing on Agnathia-Otocephaly complex

OBJECTIVES

Agnathia-otocephaly complex is a rare condition characterized by mandibular hypoplasia or agnathia, ear anomalies (melotia/synotia) and microstomia with aglossia. This severe anomaly of the first branchial arch is most often lethal. The estimated incidence is less than 1 in 70.000 births, with etiologies linked to both genetic and teratogenic factors. Most of the cases are sporadic. To date, two genes have been described in humans to be involved in this condition: OTX2 and PRRX1. Nevertheless, the overall proportion of mutated cases is unknown and a significant number of patients remain without molecular diagnosis. Thus, the involvement of other genes than OTX2 and PRRX1 in the agnathia-otocephaly complex is not unlikely. Heterozygous mutations in Cnbp in mice are responsible for mandibular and eye defects mimicking the agnathia-otocephaly complex in humans and appear as a good candidate. Therefore, in this study, we aimed (i) to collect patients presenting with agnathia-otocephaly complex for screening CNBP, in parallel with OTX2 and PRRX1, to check its possible implication in the human phenotype and (ii) to compare our results with the literature data to estimate the proportion of mutated cases after genetic testing.

MATERIALS AND METHODS

In this work, we describe 10 patients suffering from the agnathia-otocephaly complex. All of them benefited from array-CGH and Sanger sequencing of OTX2, PRRX1 and CNBP. A complete review of the literature was made using the Pubmed database to collect all the patients described with a phenotype of agnathia-otocephaly complex during the 20 last years (1998-2019) in order (i) to study etiology (genetic causes, iatrogenic causes…) and (ii), when genetic testing was performed, to study which genes were tested and by which type of technologies.

RESULTS

In our 10 patients' cohort, no point mutation in the three tested genes was detected by Sanger sequencing, while array-CGH has allowed identifying a 107-kb deletion encompassing OTX2 responsible for the agnathia-otocephaly complex phenotype in 1 of them. In 4 of the 70 cases described in the literature, a toxic cause was identified and 22 out the 66 remaining cases benefited from genetic testing. Among those 22 patients, 6 were carrying mutation or deletion in the OTX2 gene and 4 in the PRRX1 gene. Thus, when compiling results from our cohort and the literature, a total of 32 patients benefited from genetic testing, with only 34% (11/32) of patients having a mutation in one of the two known genes, OTX2 or PRRX1.

CONCLUSIONS

From our work and the literature review, only mutations in OTX2 and PRRX1 have been found to date in patients, explaining around one third of the etiologies after genetic testing. Thus, agnathia-otocephaly complex remains unexplained in the majority of the patients, which indicates that other factors might be involved. Although involved in first branchial arch defects, no mutation in the CNBP gene was found in this study. This suggests that mutations in CNBP might not be involved in such phenotype in humans or that, unlike in mice, a compensatory effect might exist in humans. Nevertheless, given that agnathia-otocephaly complex is a rare phenotype, more patients have to be screened for CNBP mutations before we definitively conclude about its potential implication. Therefore, this work presents the current state of knowledge on agnathia-otocephaly complex and underlines the need to expand further the understanding of the genetic bases of this disorder, which remains largely unknown.

CLINICAL RELEVANCE

We made here an update and focus on the clinical and genetic aspects of agnathia-otocephaly complex as well as a more general review of craniofacial development.

Agnathia otocephaly: A case from the Katanga Copperbelt

BACKGROUND

Agnathia otocephaly is a rare craniofacial malformation complex characterised by absent/hypoplastic mandible, abnormally positioned ears meeting at level of neck. Besides mutations in two genes, PRRX1 and OTX2, a teratogenic cause has been suggested. A higher risk of congenital malformations has been associated with paternal work in mining in the Democratic Republic of the Congo's part of the Copperbelt.

CASE

We studied a female neonate with a clinical diagnosis of agnathia otocephaly, stillborn in Lubumbashi in 2019. The child's father had been working as an artisanal mineworker at the time of conception.

RESULTS

Genetic analysis did not reveal a causal mutation. The concentrations of cobalt, arsenic cadmium, and uranium in cord blood of the infant were much higher than those of normal neonates from a previous study.

CONCLUSION

In the absence of identified genetic causes, we hypothesize this case of agnathia otocephaly was related to an exogenous cause, possibly the father's mining-related job.

Expanding the spectrum of SMAD3-related phenotypes to agnathia-otocephaly

Background

Agnathia‐otocephaly is a rare and lethal anomaly affecting craniofacial structures derived from the first pharyngeal arch. It is characterized by agnathia, microstomia, aglossia, and abnormally positioned auricles with or without associated anomalies. Variants affecting function of OTX2 and PRRX1, which together regulate the neural crest cells and the patterning of the first pharyngeal arch as well as skeletal and limb development, were identified to be causal for the anomaly in a few patients.

Methods

Family‐based exome sequencing (ES) on a fetus with severe agnathia‐otocephaly, cheilognathopalatoschisis, laryngeal hypoplasia, fused lung lobes and other organ abnormalities and mRNA expression analysis were performed.

Results

Exome sequencing detected a de novo SMAD3 missense variant in exon 6 (c.860G>A) associated with decreased mRNA expression. Variants in SMAD3 cause Loeys–Dietz syndrome 3 presenting with craniofacial anomalies such as mandibular hypoplasia, micro‐ or retro‐gnathia, bifid uvula and cleft palate as well as skeletal anomalies and arterial tortuosity.

The SMAD3 protein acts as a transcriptional regulator in the transforming growth factor β (TGFB) and bone morphogenetic (BMP) signaling pathways, which play a key role in the development of craniofacial structures originating from the pharyngeal arches.

Conclusion

Agnathia‐otocephaly with or without associated anomalies may represent the severe end of a phenotypic spectrum related to variants in genes in the interacting SMAD/TGFB/BMP/SHH/FGF developmental pathways.

Stable transmission of complex chromosomal rearrangements involving chromosome 1q derived from constitutional chromoanagenesis

Background

Chromoanagenesis events encompassing chromoanasynthesis, chromoplexy, and chromothripsis are described in cancers and can result in highly complex chromosomal rearrangements derived from ‘all-at-once’ catastrophic cellular events. The complexity of these rearrangements and the original descriptions in cancer cells initially led to the assumption that it was an acquired anomaly. While rare, these phenomena involving chromosome 1 have been reported a few individuals in a constitutional setting.

Case presentation

Here, we describe a newborn baby who was initially referred for cytogenetic testing for multiple congenital anomalies including cystic encephalomalacia, patent ductus arteriosus, inguinal hernia, and bilateral undescended testicles. Chromosome analysis was performed and revealed a derivative chromosome 1 with an 1q24-q31 segment inserted into 1q42.13 resulting in gain of 1q24-q31. Whole genome SNP microarray analysis showed a complex pattern of copy number variants with four gains and one loss involving 1q24-q31. Mate pair next-generation sequencing analysis revealed 18 chromosome breakpoints, six gains along an 1q24-q31 segment, one deletion of 1q31.3 segment and one deletion of 1q42.13 segment, which is strongly evocative of a chromoanasynthesis event for developing this complex rearrangement. Parental chromosome analyses were performed and showed the same derivative chromosome 1 in the mother.

Conclusions

To our knowledge, our case is the first case with familial constitutional chromoanagenesis involving chromosome 1q24-q42. This report emphasizes the value of performing microarray and mate pair next-generation sequencing analysis for individuals with germline abnormal or complex chromosome rearrangements.

First-Trimester Diagnosis of Agnathia-Otocephaly Complex: A Series of 4 Cases and Review of the Literature

First-trimester ultrasound findings in 4 fetuses with agnathia-otocephaly complex are described. In addition, information from 3 cases reported in the literature was also reviewed, for a total of 7 cases analyzed. All 7 fetuses presented with agnathia and 6 with ventrocaudal displacement of the ears (melotia/synotia). Four fetuses had holoprosencephaly. In 6 cases, the parents opted for termination of pregnancy. The remaining case resulted in premature delivery at 26 weeks due to severe polyhydramnios and early neonatal death. This report highlights the important role of ultrasound in the identification of agnathia-otocephaly complex in the first trimester of pregnancy.

Syndromes associated with holoprosencephaly

Holoprosencephaly (HPE) is partial or complete failure of the forebrain to divide into hemispheres and can be an isolated finding or associated with a syndrome. Most cases of HPE are associated with a syndrome and roughly 40%-60% of fetuses with HPE have trisomy 13 which is the most common etiology of HPE. Other syndromes associated with HPE include additional aneuploidies like trisomy 18 and single gene disorders such as Smith-Lemli-Opitz syndrome. There are a number of syndromes such as pseudotrisomy 13 which do not have a known molecular etiology; therefore, this review has two parts: syndromes with a molecular diagnosis and syndromes where the etiology is yet to be found. As most HPE is syndromic, this review provides a comprehensive list and description of syndromes associated with HPE that may be used as a differential diagnosis and starting point for evaluating individuals with HPE.

Cyclopia: isolated and with agnathia-otocephaly complex

Cyclopia is a rare form of lethal holoprosencephaly (HPE) due to incomplete cleavage of prosencephalon during embryogenesis, leading to failure of the orbits of the eye to divide into two cavities. We report two cases, one with cyclopia and another case of cyclopia with agnathia-otocephaly complex (AOC). AOC (also known as agnathia-microstomia-synotia syndrome) is a rare lethal congenital malformation of the first branchial arch characterised by the association of agnathia (agenesis of mandible) or mandibular hypoplasia, melotia (anteromedial malposition of ears), microstomia (small mouth), aglossia or microglossia (absent or rudimentary tongue). These two reported cases had in common a single eye and alobar HPE. The first case was live born and the second stillborn. Both mothers did not have antenatal care.

Prenatal Diagnosis of Isolated Agnathia-Otocephaly: A Case Report and Review of the Literature

Agnathia is a rare disease characterized by the absence of a mandible. Few cases of prenatally diagnosed isolated agnathia have been reported. We present a case report and review of the literature of prenatally diagnosed agnathia. A 38-year-old woman (gravida 0, para 0) was referred to our hospital at 28 weeks and 3 days of gestation for fetal evaluation because of polyhydramnios and suspected facial anomalies. Three-dimensional ultrasonography and MRI indicated agnathia. Premature rupture of the membranes occurred before the parents could reach a decision on the postnatal treatment. We performed emergency cesarean section on the second day of the 33rd week of gestation. The neonate was deemed nonresuscitable and he died of airway obstruction shortly after birth. Because agnathia is associated with very poor prognosis, accurate prenatal diagnosis and detailed counseling should be promptly provided before unexpected delivery to the parents for the determination of postnatal treatment.

Otocephaly: Agnathia- Microstomia-Synotia Syndrome- A Rare Congenital Anomaly

Otocephaly is a rare malformation characterized by the association of agnathia (agenesis of mandible) or mandibular hypoplasia, melotia (anteromedial malposition of ears), microstomia (small mouth), aglossia or microglossia (absent or rudimentary tongue). This rare anomaly of the ventral portion of first brachial arch is a consequence of failure of migration of neural crest cells from hind brain. It leads to the development of maxillary and mandibular prominences and starts to develop at the fourth and fifth week of gestation. We hereby present the autopsy findings of a fetus of 28 weeks gestation abortus having otocephaly without holoprosencephaly.

Agnathia Holoprosencephaly and Situs Inversus in A Neonate Born to an Alcoholic Mother

Agnathia, holoprosencephaly and situs inversus complex is an extremely rare form of congenital malformation. Though a few cases have been reported from other parts of the world, to the best of our knowledge none has been reported from India so far. Maternal alcoholism is regarded as an important factor causing holoprosencephaly. Disruption of the Shh gene signaling pathway is also said to be a factor for the occurrence of holoprosencephaly as well as left right asymmetry. Though several factors are suspected as a cause of this deformity, the precise aetiopathogenesis is still under debate. Lack of knowledge might be due to paucity of data from cases due to its rarity. Hereby, we are presenting a case of agnathia, holoprosencephaly and situs inversus born at 32 wk of gestation by an alcoholic mother. Externally the child had agnathia and cyclopia. There was no mandible or any oral cavity. It was accompanied by noticeable limb deformity. Internally there was holoprosencephaly, situs inversus totalis with several visceral abnormalities. To the best of our knowledge this is the first case of agnathia, holoprosencephaly and situs inversus complex to be reported in an indexed literature from India. This report also strengthens the association of maternal alcoholism with occurrence of holoprosencephaly.

Recurrent agnathia-otocephaly caused by DNA replication slippage in PRRX1

Agnathia-otocephaly is a rare craniofacial malformation complex that is caused by de novo heterozygous and biallelic mutations in PRRX1 in two unrelated babies, respectively. We studied the PRRX1 gene in a non-consanguineous Indonesian female infant who was diagnosed prenatally with severe retrognathia (bilateral Pruzansky type III). Her older affected brother died shortly after birth and had agnathia-otocephaly. A c.266_269dupAAAA frameshift mutation in the poly A tract in PRRX1 was identified in the proband while her father only had an inframe duplication (c.267_269dupAAA) of the adenosine trinucleotide residue. Expression of both mutations in COS7 cells showed loss of function of the frame shift mutation only. Results of SNP genotyping coupled with recurrence of this novel mutation in this family are consistent with a paternally derived germline mosaicism rather than autosomal recessive inheritance as predicted by the family history. Severe retrognathia (bilateral Pruzansky III) and agnathia-otocephaly represent a spectrum of craniofacial malformations in this family.

Cyclopia: an epidemiologic study in a large dataset from the International Clearinghouse of Birth Defects Surveillance and Research

Cyclopia is characterized by the presence of a single eye, with varying degrees of doubling of the intrinsic ocular structures, located in the middle of the face. It is the severest facial expression of the holoprosencephaly (HPE) spectrum. This study describes the prevalence, associated malformations, and maternal characteristics among cases with cyclopia. Data originated in 20 Clearinghouse (ICBDSR) affiliated birth defect surveillance systems, reported according to a single pre-established protocol. A total of 257 infants with cyclopia were identified. Overall prevalence was 1 in 100,000 births (95%CI: 0.89-1.14), with only one program being out of range. Across sites, there was no correlation between cyclopia prevalence and number of births (r = 0.08; P = 0.75) or proportion of elective termination of pregnancy (r = -0.01; P = 0.97). The higher prevalence of cyclopia among older mothers (older than 34) was not statistically significant. The majority of cases were liveborn (122/200; 61%) and females predominated (male/total: 42%). A substantial proportion of cyclopias (31%) were caused by chromosomal anomalies, mainly trisomy 13. Another 31% of the cases of cyclopias were associated with defects not typically related to HPE, with more hydrocephalus, heterotaxia defects, neural tube defects, and preaxial reduction defects than the chromosomal group, suggesting the presence of ciliopathies or other unrecognized syndromes. Cyclopia is a very rare defect without much variability in prevalence by geographic location. The heterogeneous etiology with a high prevalence of chromosomal abnormalities, and female predominance in HPE, were confirmed, but no effect of increased maternal age or association with twinning was observed.

Holoprosencephaly and agnathia spectrum: Presentation of two new patients and review of the literature

Holoprosencephaly (HPE), the most common developmental disorder of the human forebrain, is occasionally associated with the spectrum of agnathia, or virtual absence of the mandible. This condition results in a constellation of structural cerebral and craniofacial abnormalities. Here we present two new patients and review 30 patients from the literature with HPE and variants of agnathia. The majority of these patients are female and have the most severe forms of HPE, with cyclopia present more frequently than is usually observed in cohorts of patients with HPE. Also, many patients have additional clinical findings not typical in patients with classic HPE, particularly situs abnormalities. Recent animal studies suggest that the association of HPE and agnathia may relate to alterations in signaling from forebrain and foregut endoderm organizing centers and subsequent first pharyngeal arch development, although present models are inadequate to explain all of the clinical findings of this enigmatic human syndrome. Further research is required to better elucidate the causal and pathogenic basis of this association.