Microdeletion Of Chromosome 22q11 Research Articles

Genetic insights into the Tetralogy of Fallot

Tetralogy of Fallot (TOF), (OMIM #187500) one of the first known congenital heart disease (CHDs) with a rising frequency of adult patients, is a suitable paradigm for our analysis given the expanding abundance of genetic data available and these clinical consequences. Given the complexity of cardiac development, it has been associated with untreated maternal diabetes, maternal intake of retinoic acid, phenylketonuria, chromosomal anomalies (trisomies 21, 18, 13), microdeletions of chromosome 22q11.2, and it is not unexpected that a variety of transcription factors and signaling molecules involved in 9 cardiogenesis have been linked to TOF, with the literature consistently reporting the existence of new, previously unrecognized genes. The well studied genes GATA4, NKX2.5, JAG1, FOXC2, TBX5, and TBX1, which have previously been linked to TOF, are the focus of this review.

Unique Considerations in the Treatment of Psychosis in DiGeorge Syndrome: A Case Report

AbstractIntroductionDiGeorge Syndrome is a microdeletion of chromosome 22q11.2 and is most commonly de novo. Manifestations of DiGeorge are wide-spread including cardiac malformations, palatal abnormalities, intellectual disability, hypocalcemia, dysmorphic facial features, and psychiatric disorders (psychotic disorders, Autism, ADHD, etc). This case report highlights difficulties with diagnosis and treatment of psychosis in DiGeorge. This 29 yo male with history of DiGeorge and associated cardiac anomalies presented to the outpatient clinic with prior diagnoses of schizoaffective disorder, bipolar disorder, DMDD, autism, and ADHD. Patient denied all symptoms, though mother noted hallucinations for 5–6 years. He was previously on aripiprazole and divalproex and developed a resting tremor. With family history of Parkinson’s disease (PD), increased risk of PD in DiGeorge, and no improvement in tremor with dose reduction of aripiprazole or discontinuation of divalproex, neurology diagnosed PD, which was later negated when tremor resolved with complete discontinuation of aripiprazole. In our clinic we slowly increased divalproex and olanzapine, though parent concern of sedation limited higher doses. Patient had moderate improvement in symptoms per parents, but after several months on moderate-dose olanzapine, he developed a tremor. Sensitivity to extrapyramidal symptoms limits medication selection. Furthermore, QT prolongation in a population with cardiac abnormalities poses a unique risk. Given complexity and poor response, we researched pathogenesis and treatment of psychosis in DiGeorge.MethodsWe reviewed literature on PubMed with keywords including “DiGeorge,” “treatment,” “psychosis.” Specifically, we looked at articles addressing treatment response, efficacy, side effects, novel treatments, and the pathogenesis as it relates to treatment.ResultsLiterature indicates that psychotic symptoms are more treatment resistant compared to psychotic disorders not associated with DiGeorge and there is little consensus on which antipsychotics are more effective. The 22q11.2 deletion contains the gene segment for catechol-O-methyltransferase (COMT) and the resulting COMT deficiency leads to excess catecholamines. The presence of the low activity COMT variant on the remaining allele is associated with possibly more severe psychiatric symptoms. Metyrosine may be a potential medication in the treatment of psychosis in DiGeorge by interfering with dopamine synthesis. Overall there is sparse research on treatment of psychosis in DiGeorge and a lack of firm recommendations.ConclusionThis case study exemplifies the need for further research on DiGeorge Syndrome and treatment of psychosis. Treatment is complicated by cardiac abnormalities, comorbid neuropsychiatric conditions confounding diagnosis, and little research on treatments that target the unique pathogenesis. Research is inconsistent concerning recommendations and novel treatments are primarily anecdotal.FundingNo Funding

Airway Characteristics of Patients With 22q11 Deletion Undergoing Pulmonary Artery Reconstruction Surgery: Retrospective Cohort Study.

We have previously shown that patients with a chromosome 22q11 microdeletion are at risk for prolonged respiratory failure after pulmonary artery reconstruction surgery compared with those with normal genotype. We sought to describe preexisting airway abnormalities in this patient population and examine relationships between airway abnormalities and outcomes. Single-center retrospective chart review from Society of Thoracic Surgery and Pediatric Cardiac Critical Care Consortium databases and the electronic medical record. Lucile Packard Children's Hospital at Stanford from September 2017 to February 2019. All patients undergoing pulmonary artery reconstruction surgery were considered for inclusion. We identified 127 patients meeting study inclusion criteria. Thirty-nine patients met specific criteria and underwent screening preoperative bronchoscopy including microdirect laryngoscopy and lower airway examination. Postoperative bronchoscopy was performed at the discretion of the intensive care team. Airway abnormalities were detected in 25/26 of children (96%) with a chromosome 22q11 deletion who underwent preoperative bronchoscopy. Upper and lower airway pathologies were found in 19/25 (73%) and 21/25 (81%) patients, respectively, and it was common for patients to have more than one abnormality. Presence of 22q11 deletion was associated with longer duration of mechanical ventilation (9.1 vs 4.3 d; p = 0.001), use of noninvasive positive pressure support (13 vs 6 d; p = 0.001), and longer hospital stays (30 vs 14 d; p = 0.002). These outcomes were worse when compared with patients with known airway abnormalities who did not have 22q11 deletion. Preexisting upper and lower airway pathologies are common in patients with a chromosome 22q11 deletion who undergo pulmonary artery reconstruction surgery. Despite similar postoperative hemodynamics and outcomes as their counterparts without 22q11 deletion, 22q11 deletion is associated with more postoperative respiratory complications not entirely explained by preexisting airway abnormalities.

Taiwanese Clinical Experience with Noninvasive Prenatal Testing for DiGeorge Syndrome

Objective: DiGeorge syndrome (DGS) is associated with microdeletions of chromosome 22q11. It is the second most common cause of congenital heart disease and is an important consideration whenever a conotruncal cardiac anomaly is identified. The availability of noninvasive prenatal testing (NIPT) is altering the practice of prenatal genetics and maternal-fetal medicine, resulting in a decline in invasive testing. Antenatal ultrasound and other biomarkers have their own limitation. NIPT was proposed to screen DGS with cell-free DNA in Taiwan. Here, we present our experience of prenatal diagnosis of DGS in our center. Methods: This was a retrospective study between November 1, 2019, and August 31, 2020, in Taiwan. Data were collected from 7,826 pregnant women self-referred for DGS screening with massive parallel shotgun sequencing-based NIPT. High-risk cases subsequently received amniocentesis for array comparative genomic hybridization (aCGH) to confirm the diagnosis. Characteristics of pregnancies were documented when participants received the test. Report of NIPT was completed 2 weeks after the test. Follow-up on high-risk cases was completed by telephone interview on January 30, 2021. Results: Thirteen cases showed high risk by NIPT, and 7 cases were confirmed by aCGH. The sensitivity and specificity were 100% (95% confidence interval [CI] 64.57–100.00%) and 99.92% (95% CI 99.83–99.96%). The prevalence of DGS was 1 in 1,118 pregnancies. The positive predictive rate was 53.85% (95% CI 29.14–76.79%). One true positive (TP) showed US anomaly, and 5 TPs selected termination. Discussion/Conclusion: NIPT demonstrated good performance in DGS screening. Detection of 22q11.2 deletion could be combined with routine screening to facilitate proper intervention.

Prenatal ultrasonic characteristics and genetic analysis of fetuses with chromosome 22q11 microdeletion syndrome

To analyze the prenatal ultrasonic characteristics and genetic features of 14 fetuses with chromosome 22q11 microdeletion syndrome (22q11DS). 4989 fetuses were analyzed by using single nucleotide polymorphism array (SNP array) in the Fujian Maternal and Child Health Hospital from November 2016 to November 2019. SNP array showed that 11 fetuses had classic 3 Mb microdeletion in 22q11 region, one fetus had 2.0 Mb microdeletion, and two fetuses had 1.0 Mb microdeletion. The 1.0 Mb microdeletion in 22q11 region contains SNAP29 and CRKL genes, which may increase the risk of congenital renal malformation and cardiovascular malformation. Prenatal ultrasonic characteristics of fetuses with 22q11 microdeletion syndrome vary, and SNP array is a powerful tool to diagnose such diseases, which can provide accurate genetic diagnosis and enable prenatal diagnosis.

DiGeorge syndrome presenting with seizure in neonatal period: a case report

DiGeorge syndrome is caused by a micro-deletion of chromosome 22q11.2 that disrupts development of the third and fourth pharyngeal pouches during early embryogenesis. Other structures forming at the same period are also frequently affected. So, the phenotypic spectrum shows a wide variability. In this case report, we describe a 1-month and 24-day old male child who presented with history of recurrent afebrile seizure and noisy breathing since early neonatal period. He had history of repeated chest infections. On examination, patient had stridor, facial dysmorphism, pectus excavatum and clinical features of pneumonia. Investigations revealed hypocalcaemia, hypoparathyroidism, consolidation on X-ray chest and cellular immunodeficiency. Echocardiography findings were normal. Fluorescent in situ hybridization (FISH) was performed which confirmed the diagnosis 22q11.2 deletion.
 Birdem Med J 2021; 11(2): 128-132

A novel symptomatic vascular ring in a neonate

Introduction: Vascular rings are congenital anomalies of the aortic arch system characterized by a vascular anomalies of mediastinal vessels that encircle and compress the esophagus and trachea. Aortic arch anomalies may be associated with other congenital cardiac defects or chromosomal anomalies, such as microdeletion of chromosome 22q11. In neonatal/pediatric life, clinical presentation shows stridor and difficulty in swallowing or dysphagia.

A case report of T-box 1 mutation causing phenotypic features of chromosome 22q11.2 deletion syndrome

BackgroundThe heterozygous microdeletion of chromosome 22q11.2 results in a spectrum of disorders, including DiGeorge syndrome (DGS) and velocardiofacial syndrome (VCFS), with phenotypic features that can include the classic triad of congenital heart disease (CHD), thymic aplasia and hypoparathyroidism. Such microdeletions are usually detectable by fluorescence in situ hybridization (FISH).Case presentationWe report a case of a twenty-three year-old female who presented with clinical features of chromosome 22q11.2 deletion syndrome including cardiac anomalies, hypoparathyroidism and dysmorphic facial features. FISH did not reveal a 22q11.2 microdeletion. Further genetic analysis showed T box-1 (TBX1) heterozygous mutation.ConclusionsThe TBX1 gene plays a significant role in the development of fourth pharyngeal arch structures. Mutations of TBX1, which is found at chromosome 22q11.21 can be responsible for the development of syndromes classically associated with chromosome 22q11.2 deletions. This case emphasizes that the TBX1 gene, among other genes, can be responsible for the developmental anomalies seen in these syndromes.

Assessment of airway abnormalities in patients with tetralogy of Fallot, pulmonary atresia, and major aortopulmonary collaterals.

Children with tetralogy of Fallot, pulmonary atresia, and major aortopulmonary collaterals (TOF/MAPCAs) are at risk for post-operative respiratory complications after undergoing unifocalisation surgery. Thus, we assessed and further defined the incidence of airway abnormalities in our series of over 500 children with TOF/MAPCAs as determined by direct laryngoscopy, chest computed tomography (CT), and/or bronchoscopy. The medical records of all patients with TOF/MAPCAs who underwent unifocalisation or pulmonary artery reconstruction surgery from March, 2002 to June, 2018 were reviewed. Anaesthesia records, peri-operative bronchoscopy, and/or chest CT reports were reviewed to assess for diagnoses of abnormal or difficult airway. Associations between chromosomal anomalies and airway abnormalities - difficult anaesthetic airway, bronchoscopy, and/or CT findings - were defined. Of the 564 patients with TOF/MAPCAs who underwent unifocalisation or pulmonary artery reconstruction surgery at our institution, 211 (37%) had a documented chromosome 22q11 microdeletion and 28 (5%) had a difficult airway/intubation reported at the time of surgery. Chest CT and/or peri-operative bronchoscopy were performed in 234 (41%) of these patients. Abnormalities related to malacia or compression were common. In total 35 patients had both CT and bronchoscopy within 3 months of each other, with concordant findings in 32 (91%) and partially concordant findings in the other 3. This is the largest series of detailed airway findings (direct laryngoscopy, CT, and bronchoscopy) in TOF/MAPCAS patients. Although these findings are specific to an at-risk population for airway abnormalities, they support the utility of CT and /or bronchoscopy in detecting airway abnormalities in patients with TOF/MAPCAs.

Fetal right aortic arch: associated anomalies, genetic anomalies with chromosomal microarray analysis, and postnatal outcome.

The aim of the study was to assess the associated prenatal findings, genetic anomalies with chromosomal microarray analysis (CMA) and postnatal outcome of fetal right aortic arch (RAA). This retrospective study reviewed 92 fetuses diagnosed with RAA and the findings of CMA using Affymetrix CytoScan HD array in our institution between 2013 and 2016. Postnatal data were not available for six cases, and genetic data were not available for 26 cases. Tetralogy of the Fallot was the most frequently associated anomaly. Among the 60 fetuses with known karyotype, one was 46, X, Yqh+, der(13)t(8;13)(q22.3;q33.2), one was 47, XYY and the remaining were normal. Our study showed that CMA could detect uncertain significant copy number variants in 5.2% of fetal RAA and pathogenic copy number variants in 5.2%, all of which were microdeletion in chromosome 22q11.21. The genetic anomalies, gestational age at delivery and postnatal death were not significantly different between RAA-no intracardiac anomalies and RAA-intracardiac anomalies group. One infant with aberrant left subclavian artery needed to perform a surgery for respiratory symptom. A right aortic arch is associated with 22q11.2 deletion syndrome in approximately 5% of cases, and, therefore, prenatal testing, preferably using CMA, should be offered. © 2017 John Wiley & Sons, Ltd.

Clinical Factors Associated with Cerebral Metabolism in Term Neonates with Congenital Heart Disease

To determine associations between patient and clinical factors with postnatal brain metabolism in term neonates with congenital heart disease (CHD) via the use of quantitative magnetic resonance spectroscopy. Neonates with CHD were enrolled prospectively to undergo pre- and postoperative 3T brain magnetic resonance imaging. Short-echo single-voxel magnetic resonance spectroscopy of parietal white matter was used to quantify metabolites related to brain maturation (n-acetyl aspartate, choline, myo- inositol), neurotransmitters (glutamate and gamma-aminobutyric acid), energy metabolism (glutamine, citrate, glucose, and phosphocreatine), and injury/apoptosis (lactate and lipids). Multivariable regression was performed to search for associations between (1) patient-specific/prenatal/preoperative factors with concurrent brain metabolism and (2) intraoperative and postoperative factors with postoperative brain metabolism. A total of 83 magnetic resonance images were obtained on 55 subjects. No patient-specific, prenatal, or preoperative factors associated with concurrent metabolic brain dysmaturation or elevated lactate could be identified. Chromosome 22q11 microdeletion and age at surgery were predictive of altered concurrent white matter phosphocreatine (P < .0055). The only significant intraoperative association found was increased deep hypothermic circulatory arrest time with reduced postoperative white matter glutamate and gamma-aminobutyric acid (P < .0072). Multiple postoperative factors, including increased number of extracorporeal membrane oxygenation days (P < .0067), intensive care unit, length of stay (P < .0047), seizures in the intensive care unit (P < .0009), and home antiepileptic use (P < .0002), were associated with reduced postoperative white matter n-acetyl aspartate. Multiple postoperative factors were found to be associated with altered brain metabolism in term infants with CHD, but not patient-specific, preoperative, or intraoperative factors.

Ocular Findings in Children With 22q11.2 Deletion Syndrome.

To identify the ocular features of children diagnosed as having 22q11.2 deletion syndrome in a Turkish population, which is the most common microdeletion syndrome with a wide range of facial and ocular abnormalities. Sixteen children aged between 4 months and 18 years with a microdeletion in chromosome 22q11.2 underwent a detailed ophthalmological examination including uncorrected and best corrected visual acuity testing, stereoscopic vision examination, biomicroscopic and indirect fundus examination, and ocular motility testing. All patients had at least one ocular abnormality. The major abnormalities were eyelid abnormalities (eye hooding, narrow palpebral fissure, telecanthus, hypertelorism, sparse and thin eyebrows and eyelashes, blepharitis, and distichiasis), posterior embryotoxon, and tortuous retinal vessels in at least half of the patients. Other ophthalmological disorders were refractive errors, iris remnants, and strabismus. The chromosome 22q11.2 deletion syndrome is associated with a wide range of ocular disorders, which necessitates a comprehensive eye examination for appropriate treatment and follow-up. Ocular findings sometimes can provide a clue to the diagnosis of 22q11.2 deletion. [J Pediatr Ophthalmol Strabismus. 2016;53(4):218-222].

Velocardiofacial syndrome in Mexican patients: Unusually high prevalence of congenital heart disease

IntroductionVelocardiofacial syndrome (VCFS) is the most common microdeletion syndrome with an incidence of 1:4000 live births. Its phenotype is highly variable with facial, velopharyngeal, cardiac, endocrine, immunologic and psychiatric abnormalities. It is caused by a microdeletion in chromosome 22q11.2. ObjectivesWe present 7 years of experience evaluating patients with VCFS regarding their main clinical characteristics. Material and methodsThe patients included were multidisciplinary evaluated and had a positive FISH analysis for del22q11.2. ResultsA total of 62 patients were assessed, a 34 female/28 male ratio was observed with ages ranging from 9 days to 16 years, all but one patient had typical facial features. A diagnosis of congenital heart disease was established in 97% of the patients; other clinical characteristics were identified with different percentages such as cleft palate, and hypocalcaemia. Three cases had a familial presentation. DiscussionWhile the clinical findings of this study were in general terms in keeping with the literature, it is interesting the unexpectedly high percentage of congenital heart disease identified in Mexican children with VCFS that also was the main cause for clinical referral.

The evaluation of DiGeorge syndrome gene deletion using molecular cytogenetic techniques

Background Di-George Syndrome (DGS) is known as 22q11.2 deletion syndrome. It is a genetic disorder that is being recognized with increasing frequency with a documented incidence of approximately 1 in 4000 and is the most common human deletion syndrome, typically present early in life and is rarely appearing in adult patients (1). Micro-deletion of chromosome 22q11.2 is one of the most clinically variable syndromes, with more than 180 features associated with the deletion. The syndrome is caused by genetic deletions (loss of a small part of the genetic material) found on one of the two 22nd chromosomes (2). Very rarely, patients with similar clinical features may have deletions on the chromosome 10. An accurate diagnosis is needed for the proper management of affected cases. Diagnosis relies on conventional cytogenetic and Fluorescent In Situ Hybridization (FISH) techniques. The newly developed technique, array Comparative Genomic Hybridization (aCGH), allows

Velopharyngeal insufficiency: high detection rate of genetic abnormalities if associated with additional features

ObjectiveTo review the clinical and molecular-genetic characteristics of 34 children who were referred to the clinical genetics department with a presenting diagnosis of definite or suspected velopharyngeal insufficiency (VPI, defined...

Investigation of TBX1 gene deletion in Iranian children with 22q11.2 deletion syndrome: correlation with conotruncal heart defects

BackgroundDiGeorge syndrome (DGS) is the result of a microdeletion in chromosome 22q11.2 in over 90% of cases. DGS is the second most frequent syndrome after Down syndrome and has an...

Conditional and constitutive expression of a Tbx1-GFP fusion protein in mice

BackgroundVelo-cardio-facial syndrome/DiGeorge syndrome (VCFS/DGS) is caused by a 1.5-3 Mb microdeletion of chromosome 22q11.2, frequently referred to as 22q11.2 deletion syndrome (22q11DS). This region includes TBX1, a T-box transcription factor gene that contributes to the etiology of 22q11DS. The requirement for TBX1 in mammalian development is dosage-sensitive, such that loss-of-function (LOF) and gain-of-function (GOF) of TBX1 in both mice and humans results in disease relevant congenital malformations.ResultsTo further gain insight into the role of Tbx1 in development, we have targeted the Rosa26 locus to generate a new GOF mouse model in which a Tbx1-GFP fusion protein is expressed conditionally using the Cre/LoxP system. Tbx1-GFP expression is driven by the endogenous Rosa26 promoter resulting in ectopic and persistent expression. Tbx1 is pivotal for proper ear and heart development; ectopic activation of Tbx1-GFP in the otic vesicle by Pax2-Cre and Foxg1-Cre represses neurogenesis and produces morphological defects of the inner ear. Overexpression of a single copy of Tbx1-GFP using Tbx1Cre/+ was viable, while overexpression of both copies resulted in neonatal lethality with cardiac outflow tract defects. We have partially rescued inner ear and heart anomalies in Tbx1Cre/- null embryos by expression of Tbx1-GFP.ConclusionsWe have generated a new mouse model to conditionally overexpress a GFP-tagged Tbx1 protein in vivo. This provides a useful tool to investigate in vivo direct downstream targets and protein binding partners of Tbx1.

634 Digeorge Syndrome: Cognitive and Behavioural Development from Birth to Adolescence

Background and AimsDiGeorge syndrome (DGS) is a rare disease associated with a microdeletion of chromosome 22q11.2. Among clinical signs: heart defects, immunological alterations, psychiatric disorders. DGS children present developmental delay....

Palate abnormalities in Chilean patients with chromosome 22q11 microdeletion syndrome

ObjectiveChromosome 22q11 microdeletion syndrome (del22q11) is the most frequent microdeletion syndrome in humans, with an estimated incidence of 1/4000. It is recognized as a common identifiable cause of cleft palate. We characterized palatal abnormalities in a large cohort of Chilean patients with del22q11. MethodsPatients with the deletion were evaluated by geneticists and speech pathologists, including nasopharyngoscopy when indicated. Comparisons between groups with and without palatal abnormalities were performed using Fisher's exact test and Mann–Whitney U test. ResultsTwo hundred and one patients were included in the study. Palate abnormalities were present in 154 patients (76.6%). The most frequent finding was submucous cleft palate (both classic and occult forms) seen in 80 patients (39.8% of the total group). Overt cleft palate or cleft lip/palate was seen in 30 patients (14.9%). Patients without palate abnormalities had significantly greater frequency of congenital heart disease and higher mortality. ConclusionsOur data show a high frequency of palate abnormalities without significant association with congenital heart disease. The most common types of palate defects seen in this series are usually not evident on physical examination and thus require a high index of suspicion and active evaluation through nasopharyngoscopy.

Growth in Chilean infants with chromosome 22q11 microdeletion syndrome

Chromosome 22q11 microdeletion syndrome has a wide range of clinical manifestations including congenital heart malformations, palatal defects, endocrine abnormalities, immunologic deficits, learning difficulties, and an increased predisposition to psychiatric disease. Short stature and poor weight gain in infancy are common findings and are usually seen in the absence of hormone deficiencies. An increased frequency of obesity has been observed in adolescents and adults. We generated gender-specific growth curves from 0 to 24 months of age, based on 479 length and 475 weight measurements from 138 Chilean patients with 22q11 deletion. Final adult height and weight on 25 individuals were analyzed. The 10th, 50th, and 90th centile-smoothed curves for infants were built using the LMS method and compared with World Health Organization Child Growth Standards. The 50th centile for length in the deleted patients was slightly lower than the 10th centile of WHO standards in boys and girls. The same was observed for weight, although a trend toward a gradual increase near 2 years of age was observed, particularly in boys. Average adult height was 152 cm (ranging from 143 to 162 cm) in females, corresponding to the 10th centiles of WHO standards, and 166 cm for males (160-172 cm), at the 20th centile of WHO standards. A third of the adult females and none of the males had body mass index (BMI) greater than 25. The curves should be useful to monitor growth in infants with 22q11 microdeletion syndrome.