Re-focusing on Agnathia-Otocephaly complex
Authors: C Sergi
P Calvas
N Chassaing
M J Perez
C P Chen
S Arpin
C Cabrol
J Aziza
Julie Plaisanci√©
C Dubucs
C Thauvin-Robinet
M Aubert-Mucca
T Atti√©-Bitach
D Lacombe
J Martinovic
E Colin
Journal: Clinical Oral Investigations (2021)
Discipline: CLINICAL MEDICINE
Keywords: Agnathia-otocephaly complex; CNBP; Craniofacial development; OTX2; PRRX1
Affiliations: Service de G√©n√©tique M√©dicale, H√¥pital Purpan, CHU Toulouse, Toulouse, France., D√©partement d'Anatomie et de Cytologie Pathologiques, Institut Universitaire du cancer de Toulouse, Toulouse, France., INSERM U1056, Universit√© Toulouse III, Toulouse, France., Department of Lab. Med. & Pathology (5B4.09), University of Alberta, Edmonton, AB, Canada., Unit√© d'Embryof≈ìtopathologie, Service d'Histologie Embryologie Cytog√©n√©tique, H√¥pital Necker-Enfants Malades, Assistance Publique H√¥pitaux de Paris (APHP), Paris, France., Institut Imagine, INSERM U1163, Universit√© Paris Descartes, Sorbonne Paris Cite, Paris, France., Service de G√©n√©tique M√©dicale, CRMR, CHU de Bordeaux, Bordeaux, France., INSERM U1211, Universit√© de Bordeaux, 33076, Bordeaux, France., UMR1231 GAD, Inserm - Universit√© Bourgogne-Franche Comt√©, Dijon, France., Unit√© Fonctionnelle Innovation en Diagnostic g√©nomique des maladies rares, FHU-TRANSLAD, CHU Dijon, Dijon, Bourgogne, France., Centre de R√©f√©rence maladies rares "Anomalies du D√©veloppement et syndromes malformatifs," Centre de G√©n√©tique, FHU-TRANSLAD, CHU Dijon Bourgogne, Dijon, France., Service de G√©n√©tique Clinique, Centre Hospitalier R√©gional Universitaire de Tours, Tours, France., Department of Medical Genetics, Reference Center for Developmental Abnormalities and Constitutional Bone Diseases, CHRU, Montpellier, France., Centre de G√©n√©tique Humaine, Centre Hospitalier Universitaire, Universit√© de Franche-Comt√©, Besan√ßon, France., Department of Materials Engineering, Ming Chi University of Technology, New Taipei City, Taiwan., Department de Biochimie et G√©n√©tique, Centre Hospitalier Universitaire, Angers, France., UMR CNRS 6214-INSERM 1083 and PREMMI, Universit√© d'Angers, Angers, France., Unit of Fetal Pathology, AP-HP Antoine B√©cl√®re Hospital, Clamart, France., Service de G√©n√©tique M√©dicale, H√¥pital Purpan, CHU Toulouse, Toulouse, France. ., INSERM U1056, Universit√© Toulouse III, Toulouse, France. .

Abstract:  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‚Ä? 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. 

Retracted: No

PubPeer comments:
 same mice and microscopic images duplication  Disclaimer: These potential image duplications have been detected automatically using ImageTwin http: dx.doi.org 10.1145 3019612.3019875 Although results have been curated, the automatic algorithm may have generated false positive results and cannot take into account all scientific explanations for apparent duplications like stripped and reprobed blots, time series, serial sections and reused controls. ,