scholarly journals The 22q11.2 Deletion Syndrome: A Gene Dosage Perspective

2006 ◽  
Vol 6 ◽  
pp. 1881-1887 ◽  
Author(s):  
Antonio Baldini
Keyword(s):  
Developmental Stages ◽  
Gene Dosage ◽  
Single Gene ◽  
22Q11.2 Deletion Syndrome ◽  
Genomic Region ◽  
Deletion Syndrome ◽  
Genomic Disorder ◽  
22Q11.2 Deletion ◽  
Developmental Context

The 22q11.2 deletion/DiGeorge syndrome is a relatively common “genomic” disorder that results from heterozygous deletion of a 3-Mbp segment of chromosome 22. Of the more than 30 genes deleted in this syndrome,TBX1is the only one that has been found to be mutated in some patients with a phenotype that is very similar to that of patients with the full deletion, suggesting thatTBX1haploinsufficiency is a major contributor to the syndrome’s phenotype. Multi- and single-gene mouse models have provided a considerable amount of information about the consequences of decreased and increased dosage of the genomic region (and in particular of theTbx1gene) on mouse embryonic development. Modified alleles ofTbx1, as well as conditional ablation strategies have been utilized to mapin vivothe tissues and developmental stages most sensitive to gene dosage. These experiments have revealed substantially different sensitivity to gene dosage in different tissues and at different times, underlying the importance of the developmental context within which gene dosage reduction occurs.

Psychosocial Risks and Management for Children and Adolescents With 22q11.2 Deletion Syndrome

2019 ◽  
Vol 4 (4) ◽  
pp. 633-640 ◽  
Author(s):  
Canice E. Crerand ◽  
Ari N. Rabkin
Keyword(s):  
Cognitive Abilities ◽  
Psychotic Disorders ◽  
Developmental Stages ◽  
Early Adulthood ◽  
22Q11.2 Deletion Syndrome ◽  
Deletion Syndrome ◽  
22Q11.2 Deletion ◽  
Psychosocial Risks ◽  
Empirically Supported ◽  
Specific Education

Purpose This article reviews the psychosocial risks associated with 22q11.2 deletion syndrome, a relatively common genetic condition associated with a range of physical and psychiatric problems. Risks associated with developmental stages from infancy through adolescence and early adulthood are described, including developmental, learning, and intellectual disabilities as well as psychiatric disorders including anxiety, mood, and psychotic disorders. Other risks related to coping with health problems and related treatments are also detailed for both affected individuals and their families. Conclusion The article ends with strategies for addressing psychosocial risks including provision of condition-specific education, enhancement of social support, routine assessment of cognitive abilities, regular mental health screening, and referrals for empirically supported psychiatric and psychological treatments.

scholarly journals Reproductive Health Issues for Adults with a Common Genomic Disorder: 22q11.2 Deletion Syndrome

2015 ◽  
Vol 24 (5) ◽  
pp. 810-821 ◽  
Author(s):  
Chrystal Chan ◽  
Gregory Costain ◽  
Lucas Ogura ◽  
Candice K. Silversides ◽  
Eva W.C. Chow ◽  
...  
Keyword(s):  
Reproductive Health ◽  
22Q11.2 Deletion Syndrome ◽  
Deletion Syndrome ◽  
Health Issues ◽  
Genomic Disorder ◽  
22Q11.2 Deletion

scholarly journals Identification of a DNA Methylation Episignature in the 22q11.2 Deletion Syndrome

2021 ◽  
Vol 22 (16) ◽  
pp. 8611
Author(s):  
Kathleen Rooney ◽  
Michael A. Levy ◽  
Sadegheh Haghshenas ◽  
Jennifer Kerkhof ◽  
Daniela Rogaia ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Neurodevelopmental Disorders ◽  
Clinical Presentation ◽  
22Q11.2 Deletion Syndrome ◽  
Deletion Syndrome ◽  
Mild Intellectual Disability ◽  
Genomic Disorder ◽  
22Q11.2 Deletion ◽  
Chromatin Remodelers ◽  
Genome Wide

The 22q11.2 deletion syndrome (22q11.2DS) is the most common genomic disorder in humans and is the result of a recurrent 1.5 to 2.5 Mb deletion, encompassing approximately 20–40 genes, respectively. The clinical presentation of the typical deletion includes: Velocardiofacial, Di George, Opitz G/BBB and Conotruncalanomaly face syndromes. Atypical deletions (proximal, distal or nested) are rare and characterized mainly by normal phenotype or mild intellectual disability and variable clinical features. The pathogenetic mechanisms underlying this disorder are not completely understood. Because the 22q11.2 region harbours genes coding for transcriptional factors and chromatin remodelers, in this study, we performed analysis of genome-wide DNA methylation of peripheral blood from 49 patients with 22q11.2DS using the Illumina Infinium Methylation EPIC bead chip arrays. This cohort comprises 43 typical, 2 proximal and 4 distal deletions. We demonstrated the evidence of a unique and highly specific episignature in all typical and proximal 22q11.2DS. The sensitivity and specificity of this signature was further confirmed by comparing it to over 1500 patients with other neurodevelopmental disorders with known episignatures. Mapping the 22q11.2DS DNA methylation episignature provides both novel insights into the molecular pathogenesis of this disorder and an effective tool in the molecular diagnosis of 22q11.2DS.

scholarly journals Aberrant early growth of individual trigeminal sensory and motor axons in a series of mouse genetic models of 22q11.2 deletion syndrome

2020 ◽  
Vol 29 (18) ◽  
pp. 3081-3093
Author(s):  
Zahra Motahari ◽  
Thomas M Maynard ◽  
Anastas Popratiloff ◽  
Sally A Moody ◽  
Anthony-S LaMantia
Keyword(s):  
Developmental Disorders ◽  
Axon Growth ◽  
22Q11.2 Deletion Syndrome ◽  
Deletion Syndrome ◽  
Motor Axons ◽  
22Q11.2 Deletion ◽  
Critical Determinant ◽  
Sensory Axons ◽  
Anterior Posterior

Abstract We identified divergent modes of initial axon growth that prefigure disrupted differentiation of the trigeminal nerve (CN V), a cranial nerve essential for suckling, feeding and swallowing (S/F/S), a key innate behavior compromised in multiple genetic developmental disorders including DiGeorge/22q11.2 Deletion Syndrome (22q11.2 DS). We combined rapid in vivo labeling of single CN V axons in LgDel+/− mouse embryos, a genomically accurate 22q11.2DS model, and 3D imaging to identify and quantify phenotypes that could not be resolved using existing methods. We assessed these phenotypes in three 22q11.2-related genotypes to determine whether individual CN V motor and sensory axons wander, branch and sprout aberrantly in register with altered anterior–posterior hindbrain patterning and gross morphological disruption of CN V seen in LgDel+/−. In the additional 22q11.2-related genotypes: Tbx1+/−, Ranbp1−/−, Ranbp1+/− and LgDel+/−:Raldh2+/−; axon phenotypes are seen when hindbrain patterning and CN V gross morphology is altered, but not when it is normal or restored toward WT. This disordered growth of CN V sensory and motor axons, whose appropriate targeting is critical for optimal S/F/S, may be an early, critical determinant of imprecise innervation leading to inefficient oropharyngeal function associated with 22q11.2 deletion from birth onward.

scholarly journals Pharmacological Rescue of the Brain Cortex Phenotype of Tbx1 Mouse Mutants: Significance for 22q11.2 Deletion Syndrome

2021 ◽  
Vol 14 ◽  
Author(s):  
Ilaria Favicchia ◽  
Gemma Flore ◽  
Sara Cioffi ◽  
Gabriella Lania ◽  
Antonio Baldini ◽  
...  
Keyword(s):  
Vitamin B12 ◽  
Single Gene ◽  
22Q11.2 Deletion Syndrome ◽  
Deletion Syndrome ◽  
Homologous Region ◽  
22Q11.2 Deletion ◽  
Gene And Protein Expression ◽  
Multiple Drugs ◽  
Phenotypic Rescue ◽  
The Brain

ObjectivesTbx1 mutant mice are a widely used model of 22q11.2 deletion syndrome (22q11.2DS) because they manifest a broad spectrum of physical and behavioral abnormalities that is similar to that found in 22q11.2DS patients. In Tbx1 mutants, brain abnormalities include changes in cortical cytoarchitecture, hypothesized to be caused by the precocious differentiation of cortical progenitors. The objectives of this research are to identify drugs that have efficacy against the brain phenotype, and through a phenotypic rescue approach, gain insights into the pathogenetic mechanisms underlying Tbx1 haploinsufficiency.Experimental ApproachDisease model: Tbx1 heterozygous and homozygous embryos. We tested the ability of two FDA-approved drugs, the LSD1 inhibitor Tranylcypromine and Vitamin B12, to rescue the Tbx1 mutant cortical phenotype. Both drugs have proven efficacy against the cardiovascular phenotype, albeit at a much reduced level compared to the rescue achieved in the brain.MethodsIn situ hybridization and immunostaining of histological brain sections using a subset of molecular markers that label specific cortical regions or cell types. Appropriate quantification and statistical analysis of gene and protein expression were applied to identify cortical abnormalities and to determine the level of phenotypic rescue achieved.ResultsCortical abnormalities observed in Tbx1 mutant embryos were fully rescued by both drugs. Intriguingly, rescue was obtained with both drugs in Tbx1 homozygous mutants, indicating that they function through mechanisms that do not depend upon Tbx1 function. This was particularly surprising for Vitamin B12, which was identified through its ability to increase Tbx1 gene expression.ConclusionTo our knowledge, this is only the second example of drugs to be identified that ameliorate phenotypes caused by the mutation of a single gene from the 22q11.2 homologous region of the mouse genome. This one drug-one gene approach might be important because there is evidence that the brain phenotype in 22q11.2DS patients is multigenic in origin, unlike the physical phenotypes, which are overwhelmingly attributable to Tbx1 haploinsufficiency. Therefore, effective treatments will likely involve the use of multiple drugs that are targeted to the function of specific genes within the deleted region.

scholarly journals Pharmacological rescue of the brain cortex phenotype of Tbx1 mouse mutants: significance for 22q11.2 deletion syndrome

2021 ◽  
Author(s):  
Ilaria Favicchia ◽  
Gemma Flore ◽  
Sara Cioffi ◽  
Gabriella Lania ◽  
Antonio Baldini ◽  
...  
Keyword(s):  
Vitamin B12 ◽  
Single Gene ◽  
22Q11.2 Deletion Syndrome ◽  
Deletion Syndrome ◽  
Homologous Region ◽  
22Q11.2 Deletion ◽  
Gene And Protein Expression ◽  
Multiple Drugs ◽  
Phenotypic Rescue ◽  
The Brain

ABSTRACTObjectivesTbx1 mutant mice are a widely used model of 22q11.2 deletion syndrome (22q11.2DS) because they manifest a broad spectrum of physical and behavioral abnormalities that is similar to that found in 22q11.2DS patients. In Tbx1 mutants, brain abnormalities include changes in cortical cytoarchitecture, hypothesized to be caused by the precocious differentiation of cortical progenitors. The objectives of this research are to identify drugs that have efficacy against the brain phenotype, and through a phenotypic rescue approach, gain insights into the pathogenetic mechanisms underlying Tbx1 haploinsufficiency.Experimental approachDisease modelTbx1 heterozygous and homozygous embryos. We tested the ability of two FDA-approved drugs, the LSD1 inhibitor Tranylcypromine and Vitamin B12, to rescue the Tbx1 mutant cortical phenotype. Both drugs have proven efficacy against the cardiovascular phenotype, albeit at a much reduced level compared to the rescue achieved in the brain.Methodsin situ hybridization and immunostaining of histological brain sections using a subset of molecular markers that label specific cortical regions or cell types. Appropriate quantification and statistical analysis of gene and protein expression were applied to identify cortical abnormalities and to determine the level of phenotypic rescue achieved.ResultsCortical abnormalities observed in Tbx1 mutant embryos were fully rescued by both drugs. Intriguingly, rescue was obtained with both drugs in Tbx1 homozygous mutants, indicating that they function through mechanisms that do not depend upon Tbx1 function. This was particularly surprising for Vitamin B12, which was identified through its ability to increase Tbx1 gene expression.ConclusionsTo our knowledge, this is only the second example of drugs to be identified that ameliorate phenotypes caused by the mutation of a single gene from the 22q11.2 homologous region of the mouse genome. This one drug-one gene approach might be important because there is evidence that the brain phenotype in 22q11.2DS patients is multigenic in origin, unlike the physical phenotypes, which are overwhelmingly attributable to Tbx1 haploinsufficiency. Therefore, effective treatments will likely involve the use of multiple drugs that are targeted to the function of specific genes within the deleted region.

scholarly journals In vivo evidence of microstructural hypo-connectivity of brain white matter in 22q11.2 deletion syndrome

2020 ◽  
Author(s):  
Erika Raven ◽  
Jelle Veraart ◽  
Rogier Kievit ◽  
Sila Genc ◽  
Isobel Ward ◽  
...  
Keyword(s):  
White Matter ◽  
Large Scale ◽  
22Q11.2 Deletion Syndrome ◽  
Deletion Syndrome ◽  
Typically Developing ◽  
22Q11.2 Deletion ◽  
Genetic Syndrome ◽  
Brain White Matter ◽  
Axonal Morphology

Abstract 22q11.2 Deletion Syndrome, or 22q11.2DS, is a genetic syndrome associated with high rates of schizophrenia, autism, and attention deficit hyperactivity disorder, in addition to widespread structural and functional abnormalities throughout the brain. Experimental animal models have identified neuronal connectivity deficits, e.g., decreased axonal length and complexity of axonal branching, as a primary mechanism underlying atypical brain development in 22q11.2DS. However, it is still unclear whether deficits in axonal morphology can also be observed in people with 22q11.2DS. Here, we provide an unparalleled in vivo characterisation of white matter microstructure in both typically-developing children and children with 22q11.2DS using a dedicated magnetic resonance imaging scanner which is sensitive to axonal morphology. By extracting a rich array of diffusion metrics, we present microstructural profiles of typical and atypical white matter development, and provide new evidence of connectivity differences between typically-developing and 22q11.2DS children. A recent, large-scale consortium study identified higher diffusion anisotropy and reduced overall mobility of water as hallmark microstructural alterations of white matter in 22q11.2DS, in particular for commissural fibers. We observed similar findings across all white matter tracts in this study, in addition to identifying deficits in axonal morphology. This, in combination with reduced tract volume measurements, supports the hypothesis that microstructural connectivity in 22q11.2DS is mediated by densely packed axons with disproportionately small diameters. Our findings provide insight into the in vivo mechanistic features of 22q11.2DS, and promote further investigation of shared features in neurodevelopmental and psychiatric disorders.

Surgical Management of Patients With 22q11.2 Deletion Syndrome

2019 ◽  
Vol 4 (5) ◽  
pp. 857-869
Author(s):  
Oksana A. Jackson ◽  
Alison E. Kaye
Keyword(s):  
Surgical Management ◽  
Preoperative Evaluation ◽  
Preoperative Assessment ◽  
22Q11.2 Deletion Syndrome ◽  
Deletion Syndrome ◽  
22Q11.2 Deletion ◽  
Surgical Decision ◽  
Obstructive Sleep ◽  
Spine Abnormalities ◽  
Speech Assessment

Purpose The purpose of this tutorial was to describe the surgical management of palate-related abnormalities associated with 22q11.2 deletion syndrome. Craniofacial differences in 22q11.2 deletion syndrome may include overt or occult clefting of the palate and/or lip along with oropharyngeal variances that may lead to velopharyngeal dysfunction. This chapter will describe these circumstances, including incidence, diagnosis, and indications for surgical intervention. Speech assessment and imaging of the velopharyngeal system will be discussed as it relates to preoperative evaluation and surgical decision making. Important for patients with 22q11.2 deletion syndrome is appropriate preoperative screening to assess for internal carotid artery positioning, cervical spine abnormalities, and obstructive sleep apnea. Timing of surgery as well as different techniques, common complications, and outcomes will also be discussed. Conclusion Management of velopharyngeal dysfunction in patients with 22q11.2 deletion syndrome is challenging and requires thoughtful preoperative assessment and planning as well as a careful surgical technique.

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