Transmission of the dysgnathia complex from mother to daughter

Perinatal Airway Management Mandibular Anomalies: A National Inpatient Cohort Analysis

OBJECTIVE

To characterize incidence of mandibular anomalies (MAs) and compare gestational age, airway interventions, and complications among individuals with MA phenotypes (isolated retrognathia, isolated micrognathia, syndromic micrognathia, micrognathia plus cleft palate/cleft lip and palate, agnathia/micrognathia plus cervical auricle/otocephaly, and agnathia/micrognathia plus microstomia) and unaffected individuals.

METHODS

The Healthcare Cost and Utilization Project Kids' Inpatient Database was used to collect data over a 20-year period beginning in 2000. Interventions were classified as perinatal when performed on day of life (DOL) 0 or 1 and subsequent when performed during the birth hospitalization after DOL 1. Hypoxic complications included cardiac arrest, birth asphyxia, hypoxic-ischemic encephalopathy, anoxic brain damage, intraventricular hemorrhage or cerebral infarction. Descriptive statistics are reported, and the Rao-Scott chi-square test compared groups.

RESULTS

MAs affected 119 per 100,000 birth visits. Preterm delivery was more frequent for all MA phenotypes. Individuals with MA phenotypes are more likely to require medical attention (airway intervention on DOL 0 or 1 OR no airway intervention received but patient sustained hypoxic complication/mortality): 16.2%-70.7% vs. 3.8%, p < 0.01. Despite receipt of airway interventions at a higher rate, collectively individuals with MAs who received an airway intervention on DOL 0 or 1 have a mildly elevated risk of hypoxic complication or mortality (32.4% vs. 26.4%, p < 0.01).

CONCLUSIONS

Preterm birth is more common, however, does not account for the elevated rate of airway intervention. Individuals with MAs require higher rates of medical attention, and current airway management paradigms are insufficient to prevent complications and mortality.

LEVEL OF EVIDENCE

III Laryngoscope, 2024.

Auriculocondylar syndrome: Pathogenesis, clinical manifestations and surgical therapies

Auriculocondylar syndrome (ARCND) is a genetic and rare craniofacial condition caused by abnormal development of the first and second pharyngeal arches during the embryonic stage and is characterized by peculiar auricular malformations (question mark ears), mandibular condyle hypoplasia, micrognathia and other less-frequent features. GNAI3, PLCB4 and EDN1 have been identified as pathogenic genes in this syndrome so far, all of which are implicated in the EDN1-EDNRA signal pathway. Therefore, ARCND is genetically classified as ARCND1, ARCND2 and ARCND3 based on the mutations in GNAI3, PLCB4 and EDN1, respectively. ARCND is inherited in an autosomal dominant or recessive mode with significant intra- and interfamilial phenotypic variation and incomplete penetrance, rendering its diagnosis difficult and therapies individualized. To raise clinicians' awareness of the rare syndrome, we focused on the currently known pathogenesis, pathogenic genes, clinical manifestations and surgical therapies in this review.

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.

Prenatal diagnosis of auriculocondylar syndrome with a novel missense variant of GNAI3: a case report

BACKGROUND

Auriculocondylar syndrome (ACS) is a rare disorder characterized by micrognathia, mandibular condyle hypoplasia, and auricular abnormalities. Only 6 pathogenic variants of GNAI3 have been identified associated with ACS so far. Here, we report a case of prenatal genetic diagnosis of ACS carrying a novel GNAI3 variant.

CASE PRESENTATION

A woman with 30 weeks of gestation was referred to genetic counseling for polyhydramnios and fetal craniofacial anomaly. Severe micrognathia and mandibular hypoplasia were identified on ultrasonography. The mandibular length was 2.4 cm, which was markedly smaller than the 95th percentile. The ears were low-set with no cleft or notching between the lobe and helix. The face was round with prominent cheeks. Whole-exome sequencing identified a novel de novo missense variant of c.140G > A in the GNAI3 gene. This mutation caused an amino acid substitution of p.Ser47Asn in the highly conserved G1 motif, which was predicted to impair the guanine nucleotide-binding function. All ACS cases with GNAI3 mutations were literature reviewed, revealing female-dominated severe cases and right-side-prone deformities.

CONCLUSION

Severe micrognathia and mandibular hypoplasia accompanied by polyhydramnios are prenatal indicators of ACS. We expanded the mutation spectrum of GNAI3 and summarized clinical features to promote awareness of ACS.

A novel missense variant of the GNAI3 gene and recognisable morphological characteristics of the mandibula in ARCND1

Auriculocondylar syndrome (ARCND) is an autosomal monogenic disorder characterised by external ear abnormalities and micrognathia due to hypoplasia of the mandibular rami, condyle and coronoid process. Genetically, three subtypes of ARCND (ARCND1, ARCND2 and ARCND3) have been reported. To date, five pathogenic variants of GNAI3 have been reported in ARCND1 patients. Here, we report a novel variant of GNAI3 (NM_006496:c.807C>A:p.(Asn269Lys)) in a Japanese girl with micrognathia using trio-based whole exome sequencing analysis. The GNAI3 gene encodes a heterotrimeric guanine nucleotide-binding protein. The novel variant locates the guanine nucleotide-binding site, and the substitution was predicted to interfere with guanine nucleotide-binding by in silico structural analysis. Three-dimensional computer tomography scan, or cephalogram, displayed severely hypoplastic mandibular rami and fusion to the medial and lateral pterygoid plates, which have been recognised in other ARCND1 patients, but have not been described in ARCND2 and ARCND3, suggesting that these may be distinguishable features in ARCND1.

International Pediatric Otolaryngology Group (IPOG): Consensus recommendations on the prenatal and perinatal management of anticipated airway obstruction

OBJECTIVE

To make recommendations on the identification, routine evaluation, and management of fetuses at risk for airway compromise at delivery.

METHODS

Recommendations are based on expert opinion by members of the International Pediatric Otolaryngology Group (IPOG). A two-iterative Delphi method questionnaire was distributed to all members of the IPOG and responses recorded. The respondents were given the opportunity to comment on the content and format of the survey, which was modified for the second round. "Consensus" was defined by >80% respondent affirmative responses, "agreement" by 51-80% affirmative responses, and "no agreement" by 50% or less affirmative responses.

RESULTS

Recommendations are provided regarding etiologies of perinatal airway obstruction, imaging evaluation, adjunct evaluation, multidisciplinary team and decision factors, micrognathia management, congenital high airway obstruction syndrome management, head and neck mass management, attended delivery procedure, and delivery on placental support procedure.

CONCLUSIONS

Thorough evaluation and thoughtful decision making are required to optimally balance fetal and maternal risks/benefits.

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.

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.

Mandibular dysostosis without microphthalmia caused by OTX2 deletion

Mutations in OTX2 are mostly identified in patients with anophthalmia/microphthalmia with variable severity. The OTX2 homeobox gene plays a crucial role in craniofacial morphogenesis during early embryo development. We report for the first time a patient with a mandibular dysostosis caused by a 120 kb deletion including the entire coding sequence of OTX2, identified by array CGH. No ocular malformations were identified after extended ophthalmologic examination. Our data refine the clinical spectrum associated with OTX2 mutations and suggests that OTX2 haploinsufficiency should be considered as a possible cause for isolated mandibular dysostosis. © 2016 Wiley Periodicals, Inc.

Severe micrognathia with 21 trisomy assessed prenatally by performing three-dimensional computed tomography

Severe micrognathia can lead to death shortly after birth without a proper resuscitation. However, it is difficult to develop an effective resuscitation strategy without a prenatal diagnosis of the severity of micrognathia. In the present case, we used fetal three-dimensional computed tomography (3D-CT) to assess the severity of micrognathia. Its images clearly demonstrated bony framework of mandible and suggested that mandibular hypoplasia was too severe to allow for oral intubation. We therefore decided that the ex utero intrapartum treatment (EXIT) procedure would be more appropriate to establish the airway at birth. The prenatal 3D-CT is useful to evaluate the mandibular anatomy in utero if the severity of the micrognathia is not confirmed by the ultrasound or magnetic resonance imaging (MRI).

Postnatal Diagnosis of a Baby With Multiple Rare Congenital Anomalies Including Syngnathia, Brain Dysmorphism, and Skin Pigmentation

Syngnathia is a rare congenital disorder of jaw fusion with a paucity of literature from developed countries. We present a case of an infant noted to have multiple anomalies at birth including syngnathia, microcephaly with a variant of brain abnormality between holoprosencephaly and syntelencephaly, optic nerve hypoplasia, ear canal anomalies, hemi-vertebrae, and suspected hypomelanosis of Ito. To our knowledge, this patient with syngnathia and multiple anomalies is the first to be reported, but whether they are a coincidence, a pathogenetic association, or a new syndrome remains unknown. This case is discussed with a brief review of the literature.

Novel variants in GNAI3 associated with auriculocondylar syndrome strengthen a common dominant negative effect

Auriculocondylar syndrome is a rare craniofacial disorder comprising core features of micrognathia, condyle dysplasia and question mark ear. Causative variants have been identified in PLCB4, GNAI3 and EDN1, which are predicted to function within the EDN1-EDNRA pathway during early pharyngeal arch patterning. To date, two GNAI3 variants in three families have been reported. Here we report three novel GNAI3 variants, one segregating with affected members in a family previously linked to 1p21.1-q23.3 and two de novo variants in simplex cases. Two variants occur in known functional motifs, the G1 and G4 boxes, and the third variant is one amino acid outside of the G1 box. Structural modeling shows that all five altered GNAI3 residues identified to date cluster in a region involved in GDP/GTP binding. We hypothesize that all GNAI3 variants lead to dominant negative effects.

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.

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.

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.

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 the previously 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.

Aprosencephaly with otocephaly in a lamb (Ovis aries)

Aprosencephaly is a rare condition in veterinary and human medicine characterized by the complete absence of telencephalon and diencephalon. Some cases are accompanied by a facial dysmorphism designated as otocephaly. A stillborn lamb had splanchnocranial anomalies that were classified by computed tomography, magnetic resonance imaging, and pathologic examination as aprosencephaly and otocephaly. The brain included parts of the cerebellum and brainstem but no telencephalon, diencephalon, or mesencephalon. The cerebellum had a structurally normal cortex with expression of neuronal nuclear antigen in the inner and doublecortin in the outer granular cell layers, as well as an irregularly situated nucleus dentatus. Aprosencephaly with otocephaly has been described in mice with heterozygous mutations in the Otx2 gene; however, no causative polymorphisms were detected in the Otx2 gene region of this lamb.

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.

Holoprosencephaly at prenatal diagnosis: analysis of 28 cases regarding etiopathogenic diagnoses

OBJECTIVE

To assess the likelihood of finding an etiopathogenic cause in an ultrasonographic prenatal diagnosis of holoprosencephaly.

MATERIALS AND METHODS

From January 1996 to June 2010, 13 883 prenatal diagnoses through chorionic villus sampling or amniocentesis were made. Every fetus with holoprosencephaly at ultrasound was evaluated. Gestational age, additional ultrasound findings, and fetal karyotype were recorded. Molecular diagnosis and parental karyotype were studied, if relevant.

RESULTS

Twenty-eight fetuses were diagnosed with holoprosencephaly (0.20%). All cases had additional ultrasound findings (100%). A definitive etiology was found in 23 cases (82.14%): karyotype was abnormal in 19 (67.9%) and normal in 8 (28.5%) cases. In the normal karyotype group, although molecular testing was performed in a few cases, one mutation of gene SIX 3 was diagnosed, one diagnosis of dysgnathia complex was made, and two fetuses presented Smith-Lemli-Opitz syndrome. No etiopathogenic diagnosis was made in five fetuses.

CONCLUSIONS

Our results showed that a definitive etiology can be established in most cases of prenatal holoprosencephaly. Chromosomal anomalies were the most frequent finding. However, in euploid fetuses, molecular diagnosis is worthwhile, as different genes with different inheritance patterns may be responsible for this malformation. Thorough evaluation proved beneficial for assessing more accurate prognosis and recurrence risks.

Glyphosate-based herbicides produce teratogenic effects on vertebrates by impairing retinoic acid signaling

The broad spectrum herbicide glyphosate is widely used in agriculture worldwide. There has been ongoing controversy regarding the possible adverse effects of glyphosate on the environment and on human health. Reports of neural defects and craniofacial malformations from regions where glyphosate-based herbicides (GBH) are used led us to undertake an embryological approach to explore the effects of low doses of glyphosate in development. Xenopus laevis embryos were incubated with 1/5000 dilutions of a commercial GBH. The treated embryos were highly abnormal with marked alterations in cephalic and neural crest development and shortening of the anterior-posterior (A-P) axis. Alterations on neural crest markers were later correlated with deformities in the cranial cartilages at tadpole stages. Embryos injected with pure glyphosate showed very similar phenotypes. Moreover, GBH produced similar effects in chicken embryos, showing a gradual loss of rhombomere domains, reduction of the optic vesicles, and microcephaly. This suggests that glyphosate itself was responsible for the phenotypes observed, rather than a surfactant or other component of the commercial formulation. A reporter gene assay revealed that GBH treatment increased endogenous retinoic acid (RA) activity in Xenopus embryos and cotreatment with a RA antagonist rescued the teratogenic effects of the GBH. Therefore, we conclude that the phenotypes produced by GBH are mainly a consequence of the increase of endogenous retinoid activity. This is consistent with the decrease of Sonic hedgehog (Shh) signaling from the embryonic dorsal midline, with the inhibition of otx2 expression and with the disruption of cephalic neural crest development. The direct effect of glyphosate on early mechanisms of morphogenesis in vertebrate embryos opens concerns about the clinical findings from human offspring in populations exposed to GBH in agricultural fields.

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.

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.

Computed tomographic reconstruction of a fetus with the dysgnathia complex (agnathia-otocephaly)

The dysgnathia complex (agnathia-otocephaly) (AO) is a lethal malformation that consists of congenital absence of the lower jaw with union or close approximation of the lower ears on the front of the neck, microstomia, and hypoglossia. We present a novel case of agnathia-otocephaly with associated organomegaly and the use of postmortem 3-D computed tomographic rendering.

Otocephaly: report of five new cases and a literature review

Otocephaly, characterized by mandibular hypoplasia or agnathia, ventromedial auricular malposition (melotia) and/or auricular fusion (synotia), and microstomia with oroglossal hypoplasia or aglossia, is an extremely rare anomalad, identified in less than 1 in 70,000 births. The malformation spectrum is essentially lethal, because of ventilatory problems, and represents a developmental field defect of blastogenesis primarily affecting thefirst branchial arch derivatives. Holoprosencephaly is the most commonly identified association, but skeletal, genitourinary, and cardiovascular anomalies, and situs inversus have been reported. Polyhydramnios may be the presenting feature, but prenatal diagnosis has been uncommon. We present five new cases of otocephaly, the largest published series to date, with comprehensive review of the literature and an update of research in the etiopathogenesis of this malformation complex. One of our cases had situs inversus, and two presented with unexplained polyhydramnios. Otocephaly, while quite rare, should be considered in the differential diagnosis of this gestational complication.

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.

Auriculo-condylar syndrome: Additional patients

This report describes several relatives in three generations of one family and another, unrelated boy with auriculo-condylar syndrome, a rare autosomal dominant disorder. Variation in the severity of the abnormalities was observed. We discuss the findings in our patients in relation to those in the literature.