Variants in a cis-regulatory element of TBX1 in conotruncal heart defect patients impair GATA6-mediated transactivation

Background TBX1 (T-box transcription factor 1) is a major candidate gene that likely contributes to the etiology of velo-cardio-facial syndrome/DiGeorge syndrome (VCFS/DGS). Although the haploinsufficiency of TBX1 in both mice and humans results in congenital cardiac malformations, little has been elucidated about its upstream regulation. We aimed to explore the transcriptional regulation and dysregulation of TBX1. Methods Different TBX1 promoter reporters were constructed. Luciferase assays and electrophoretic mobility shift assays (EMSAs) were used to identify a cis-regulatory element within the TBX1 promoter region and its trans-acting factor. The expression of proteins was identified by immunohistochemistry and immunofluorescence. Variants in the cis-regulatory element were screened in conotruncal defect (CTD) patients. In vitro functional assays were performed to show the effects of the variants found in CTD patients on the transactivation of TBX1. Results We identified a cis-regulatory element within intron 1 of TBX1 that was found to be responsive to GATA6 (GATA binding protein 6), a transcription factor crucial for cardiogenesis. The expression patterns of GATA6 and TBX1 overlapped in the pharyngeal arches of human embryos. Transfection experiments and EMSA indicated that GATA6 could activate the transcription of TBX1 by directly binding with its GATA cis-regulatory element in vitro. Furthermore, sequencing analyses of 195 sporadic CTD patients without the 22q11.2 deletion or duplication identified 3 variants (NC_000022.11:g.19756832C > G, NC_000022.11:g.19756845C > T, and NC_000022.11:g. 19756902G > T) in the non-coding cis-regulatory element of TBX1. Luciferase assays showed that all 3 variants led to reduced transcription of TBX1 when incubated with GATA6. Conclusions Our findings showed that TBX1 might be a direct transcriptional target of GATA6, and variants in the non-coding cis-regulatory element of TBX1 disrupted GATA6-mediated transactivation.

Cell adhesions link subcellular actomyosin dynamics to tissue scale force production during vertebrate convergent extension.

Axis extension is a fundamental biological process that shapes multicellular organisms. The design of the animal body plan is encoded in the genome and execution of this program is a multiscale mechanical progression involving the coordinated movement of proteins, cells, and whole tissues. Thus, a key challenge to understanding axis extension is connecting events that occur across these various length scales. Here, we use approaches from proteomics, cell biology, and tissue biomechanics to describe how a poorly characterized cell adhesion effector, the Armadillo Repeat protein deleted in Velo-Cardio-Facial syndrome (Arvcf) catenin, controls vertebrate head-to-tail axis extension. We find that Arvcf catenin is required for axis extension within the intact organism but is not required for extension of isolated tissues. We then show that the organism scale phenotype is caused by a modest defect in force production at the tissue scale that becomes apparent when the tissue is challenged by external resistance. Finally, we show that the tissue scale force defect results from dampening of the pulsatile recruitment of cell adhesion and cytoskeletal proteins to cell membranes. These results not only provide a comprehensive understanding of Arvcf function during an essential biological process, but also provide insight into how a modest cellular scale defect in cell adhesion results in an organism scale failure of development.

Human and Animal Studies in Craniofacial Embryology Enrich Human Postnatal Craniofacial Insight Differently

Objectives: To compare results obtained since 1970 from craniofacial embryological studies on human fetal tissues with results from similar studies performed on animal tissues and focus on how the different tissue types and methods can enrich the human postnatal craniofacial research. There are three sections: i) research on normal and pathological human fetal material, ii) animal experimental research performed on different species, and iii) comparisons of the results obtained. Human Material: On human prenatal material, normal and pathological developmental processes in the mandible, maxilla, nasal cavity, body axis, cranial base, vomeronasal organs, pituitary gland and nervous system were related to postnatal findings. Specific focus was given to pre/postnatal bridging of observations on holoprosencephaly, cleft lip/palate, Down syndrome, myelomeningocele/spina bifida, Kallmann syndrome, Turner syndrome and Fragile X syndrome. Demarcations of pathological regions in Cri du chat, Velo-cardio-Facial syndrome and Crouzon syndrome were mapped. Animal Material: Animal experimental results from studies on the notochord, gastrulation, neural crest, hindbrain, rhombomere, homeobox genes and experimentally induced malformation were presented. Comparing materials: The educational background of the scientists performing human and animal research, their postnatal clinical experience, the research materials used and the methods available for research are compared. Furthermore, the obtained findings result in a “pro et contra list” indicating what is positive and what is negative for improving postnatal human diagnostics. Conclusion: Human and animal studies in craniofacial embryology enrich human postnatal craniofacial insight differently. Future cooperation between human and animal research cultures is recommended.

Clinical and Demographical Characteristics of Cleft Lip and/or Palate in the Northwest of Iran: An Analysis of 1500 Patients

Objective: Orofacial clefts (OFCs) can occur as an isolated defect or as a manifestation of other syndromes. The current study aimed to evaluate demographic characteristics and distribution of different types of accompanying anomalies for OFCs in the northwest of Iran. Design: A retrospective cohort study. Setting: Tertiary pediatric hospital. Patients and Participants: This study was conducted on 1500 cleft lip and/or palate patients born between July 2010 and June 2020 in the northwest of Iran. Main Outcome Measures: Demographic and clinical characteristics of the children with OFCs including familial history, accompanying anomalies and syndromes, maternal passive smoking, mothers’ and fathers’ age, consanguineous marriage, and birth order. Results: Among 1500 patients, 441 had cleft lip, 615 had cleft palate, and 444 had cleft lip and palate. The positive family history of OFCs was found to be 20.9% to 25.4% depending on the cleft type. Accompanying anomalies were identified in 29.8% of cases. Cardiac, facial, and ear abnormalities were the most common types. Also, 2.9% were identified with syndromes and sequences. These included Pierre Robin Sequence, Velo-cardio-facial syndrome, and Down syndrome most frequently. Conclusion: These findings may provide references for appropriate resources to establish and direct counseling and primary preventive projects in the northwest of Iran.

Atypical response inhibition and error processing in 22q11.2 Deletion Syndrome and Schizophrenia: Towards neuromarkers of disease progression and risk

ABSTRACT22q11.2 deletion syndrome (also known as DiGeorge syndrome or velo-cardio-facial syndrome) is characterized by increased vulnerability to neuropsychiatric symptoms, with approximately 30% of individuals with the deletion going on to develop schizophrenia. Clinically, deficits in executive function have been noted in this population, but the underlying neural processes are not well understood. Using a Go/No-Go response inhibition task in conjunction with high-density electrophysiological recordings (EEG), we sought to investigate the behavioral and neural dynamics of inhibition of a prepotent response (a critical component of executive function) in individuals with 22q11.2DS with and without psychotic symptoms, when compared to individuals with idiopathic schizophrenia and age-matched neurotypical controls. Twenty-eight participants diagnosed with 22q11.2DS (14-35 years old; 14 with at least one psychotic symptom), 15 individuals diagnosed with schizophrenia (18-63 years old) and two neurotypical control groups (one age-matched to the 22q11.2DS sample, the other age-matched to the schizophrenia sample) participated in this study. Analyses focused on the N2 and P3 no-go responses and error-related negativity (Ne) and positivity (Pe). Atypical inhibitory processing was shown behaviorally and by significantly reduced P3, Ne, and Pe responses in 22q11.2DS and schizophrenia. Interestingly, whereas P3 was only reduced in the presence of psychotic symptoms, Ne and Pe were equally reduced in schizophrenia and 22q11.2DS, regardless of the presence of symptoms. We argue that while P3 may be a marker of disease severity, Ne and Pe might be candidate markers of risk.

M76. ATYPICAL RESPONSE INHIBITION IN 22Q11.2DS: DIMINISHED ERROR REGISTRATION AND AWARENESS

Background 22q11.2 deletion syndrome (22q11.2DS; also known as DiGeorge syndrome or velo-cardio-facial syndrome) is characterized by increased vulnerability for neuropsychiatric symptoms, with approximately 30% of the individuals with the deletion developing schizophrenia. Clinically, deficits in executive function have been noted in this population, but the underlying neural processes are not well understood. Methods Using high-density electrophysiology (EEG), we investigated the neural dynamics of inhibition of a prepotent response (a critical component of executive function) in individuals with 22q11.2DS with and without psychotic symptoms. Twenty-seven individuals with 22q11.2DS (14–35 years old, 14 with at least one psychotic symptom) and 27 age-matched neurotypical controls participated in a go/no-go task while EEG was recorded. Analyses were focused on the P3 go/no-go response and error-related positivity (Pe). Results Behaviorally, individuals with 22q11.2DS were slower and unable to inhibit prepotent responses as the controls, with significantly more false alarms. Atypical inhibitory processing was confirmed by significantly reduced P3 no-go responses in the 22q11.2DS group. Such reductions were particularly marked in those with psychotic symptomatology. Pe was likewise significantly decreased (regardless of the presence of psychotic symptoms), suggesting impaired ability to register errors (i.e., false alarms) in 22q11.2DS. Both Pe and P3 correlated with clinical measures of inhibition (DKEFS and CPT). Discussion To our knowledge, this is the first study looking at electrophysiological measures of response inhibition in 22q11.2DS. P3 and Pe reductions, which have also been shown in schizophrenia, suggest diminished error registration and awareness in 22q11.2DS and, possibly, a consequent difficulty in adjusting response strategies.

22q11.2 Microduplications: Two Clinical Reports Compared with Similar Cases from the Literature

We present two male subjects (6 and 14 years old) with mild dysmorphism, intellectual disability, and/or autism spectrum disorder with chromosome 22q11.2 microduplications of different sizes. We then compared the clinical and genetic findings with similar cases from the literature sharing the same 22q11.2 duplications. These rare duplications in our subjects were identified by high-resolution chromosomal microarray analysis and flanked by low copy repeats in the 22q11.2 region, specifically LCR22A, LCR22B, and LCR22D. The typical 22q11.2 defect generally involves a deletion at breakpoints LCR22A and LCR22D causing DiGeorge or velo-cardio-facial syndrome and not duplications of varying sizes as seen in our male subjects.