Clinical Manifestations of 22q11.2 Deletion Syndrome

A case-control study of bleeding risk in children with 22q11.2 deletion syndrome undergoing cardiac surgery

Previous research suggests that individuals with 22q11.2 deletion syndrome (DS) have an increased risk of bleeding following cardiac surgery. However, current guidelines for management of patients with 22q11.2DS do not provide specific recommendations for perioperative management. This study sought to identify specific risk factors for bleeding in this patient population. Examine the factors determining bleeding and transfusion requirements in patients with 22q11.2DS undergoing cardiac surgery. This was a single center review of patients who underwent cardiac surgery at the Children's Hospital of Philadelphia from 2000 to 2016. Data was extracted from the medical record. Frequency of bleeding events, laboratory values, and transfusion requirements were compared. We included 226 patients with 22q11.2DS and 506 controls. Bleeding events were identified in 13 patients with 22q11.2DS (5.8%) and 27 controls (5.3%). Platelet counts were lower among patients with 22q11.2DS than in control patients, but not statistically different comparing bleeding to not bleeding. Patients with 22q11.2DS received more transfusions (regardless of bleeding status). However, multivariate analysis showed only procedure type was associated with increased risk of bleeding (p = .012). The overall risk of bleeding when undergoing cardiac surgery is not different in patients with 22q11.2DS compared to non-deleted patients. Though platelet counts were lower in patients with 22q11.2DS, only procedure type was significantly associated with an increased risk of bleeding.

Efficiency of copy number variation sequencing combined with karyotyping in fetuses with congenital heart disease and the following outcomes

BACKGROUND

Both copy number variant-sequencing (CNV-seq) and karyotype analysis have been used as powerful tools in the genetic aetiology of fetuses with congenital heart diseases (CHD). However, CNV-seq brings clinicians more confusions to interpret the detection results related to CHD with or without extracardiac abnormalities. Hence, we conducted this study to investigate the clinical value of CNV-seq in fetuses with CHD.

RESULTS

A total of 167 patients with fetal CHD including 36 single CHD (sCHD), 41 compound CHD (cCHD) and 90 non-isolated CHD (niCHD) were recruited into the study. 28 cases (16.77%, 28/167) were revealed with chromosomal abnormalities at the level of karyotype. The pathogenic detection rate (DR) of CNV-seq (23.17%, 19/82) was higher than that of karyotyping (15.85%, 13/82) in 82 cases by CNV-seq and karyotyping simultaneously. The DR of pathogenic copy number variations (PCNVs) (31.43%) was higher in niCHD subgroup than that in sCHD and cCHD (9.52% and 23.08%). Conotruncal defect (CTD) was one of the most common heart malformations with the highest DR of PCNVs (50%) in 7 categories of CHD. In terms of all the pregnancy outcomes, 67 (40.12%) cases were terminated and 100 (59.88%) cases were live neonates. Only two among 34 cases with a pathogenic genetic result chose to continue the pregnancy.

CONCLUSIONS

CNV-seq combined with karyotyping is a reliable and accurate prenatal technique for identifying pathogenic chromosomal abnormalities associated with fetal CHD with or without extracardiac abnormalities, which can assist clinicians to perform detailed genetic counselling with regard to the etiology and related outcomes of CHD.

Neuropsychological Profile of 25 Brazilian Patients with 22q11.2 Deletion Syndrome: Effects of Clinical and Socioeconomic Variables

The 22q11.2 deletion syndrome (22q11.2DS) is associated with a heterogeneous neurocognitive phenotype, which includes psychiatric disorders. However, few studies have investigated the influence of socioeconomic variables on intellectual variability. The aim of this study was to investigate the cognitive profile of 25 patients, aged 7 to 32 years, with a typical ≈3 Mb 22q11.2 deletion, considering intellectual, adaptive, and neuropsychological functioning. Univariate linear regression analysis explored the influence of socioeconomic variables on intellectual quotient (IQ) and global adaptive behavior. Associations with relevant clinical conditions such as seizures, recurrent infections, and heart diseases were also considered. Results showed IQ scores ranging from 42 to 104. Communication, executive functions, attention, and visuoconstructive skills were the most impaired in the sample. The study found effects of access to quality education, family socioeconomic status (SES), and caregiver education level on IQ. Conversely, age at diagnosis and language delay were associated with outcomes in adaptive behavior. This characterization may be useful for better understanding the influence of social-environmental factors on the development of patients with 22q11.2 deletion syndrome, as well as for intervention processes aimed at improving their quality of life.

Clinical Experience of Prenatal Chromosomal Microarray Analysis in 6159 Ultrasonically Abnormal Fetuses

A single-center retrospective study of G-band karyotyping and chromosomal microarray analysis (CMA) for the invasive prenatal diagnosis of 6159 fetuses with ultrasound abnormalities was conducted. This study aimed to investigate the incidence rates of chromosomal abnormalities and pregnancy outcomes and postpartum clinical manifestations by long-term follow-up and to explore the correlation between different types of prenatal ultrasound abnormalities and pathogenic chromosomal abnormalities. The overall incidence of pathogenic chromosomal aberrations in fetuses with ultrasound abnormalities was 7.58% (467/6159), which comprised 41.7% (195/467) with chromosome number abnormalities, 57.6% (269/467) with pathogenic copy-number variations (pCNVs), and 0.64% (3/467) with uniparental disomy (UPD). In addition, 1.72% (106/6159) with likely pathogenic copy-number variations (lpCNVs) and 3.04% (187/6159) with variants of unknown significance (VOUS) were detected by CMA. Ultrasound abnormalities were categorized into structural anomalies and soft marker anomalies. The incidence rate of pathogenic and likely pathogenic chromosomal abnormalities was significantly higher among fetuses with structural anomalies than soft markers (11.13% vs 7.59%, p < 0.01). We retrospectively analyzed the prenatal genetic outcomes for a large cohort of fetuses with different types of ultrasound abnormalities. The present study showed that the chromosomal abnormality rate and clinical outcomes of fetuses with different types of ultrasound abnormalities varied greatly. Our data have important implications for prenatal genetic counseling for fetuses with different types of ultrasound abnormalities.

RNA binding proteins in cardiovascular development and disease

Congenital heart disease (CHD) is the most common birth defect affecting>1.35 million newborn babies worldwide. CHD can lead to prenatal, neonatal, postnatal lethality or life-long cardiac complications. RNA binding protein (RBP) mutations or variants are emerging as contributors to CHDs. RBPs are wizards of gene regulation and are major contributors to mRNA and protein landscape. However, not much is known about RBPs in the developing heart and their contributions to CHD. In this chapter, we will discuss our current knowledge about specific RBPs implicated in CHDs. We are in an exciting era to study RBPs using the currently available and highly successful RNA-based therapies and methodologies. Understanding how RBPs shape the developing heart will unveil their contributions to CHD. Identifying their target RNAs in the embryonic heart will ultimately lead to RNA-based treatments for congenital heart disease.

Distinct Immunophenotypic Features in Patients Affected by 22q11.2 Deletion Syndrome with Immune Dysregulation and Infectious Phenotype

The clinical expression of 22q11.2 deletion syndrome (22q11.2 DS) is extremely variable, as patients can present with recurrent or severe infections, immune dysregulation, atopic diseases, or extra-immunological manifestations. The immunological background underlying the different disease manifestations is not completely elucidated. The aim of this study was to identify the immunophenotypic peculiarities of 22q11.2 DS patients presenting with different disease expressions. This study included 34 patients with 22q11.2 DS, divided into three groups according to the clinical phenotype: isolated extra-immunological manifestations (G1), infectious phenotype with increased/severe infections (G2), and immune dysregulation (G3). The patients underwent extended immunophenotyping of the T and B lymphocytes and analysis of the circulating dendritic cells (DCs). In patients with an infectious phenotype, a significant reduction in CD3+ and CD4+ cells and an expansion of CD8 naïve cells was evidenced. On the other hand, the immunophenotype of the patients with immune dysregulation showed a skewing toward memory T cell populations, and reduced levels of recent thymic emigrants (RTEs), while the highest levels of RTEs were detected in the patients with isolated extra-immunological manifestations. This study integrates the current literature, contributing to elucidating the variability in the immune status of patients with 22q11.2DS with different phenotypic expressions, particularly in those with infectious phenotype and immune dysregulation.

Navigating the transition of care in patients with inborn errors of immunity: a single-center's descriptive experience

The transition from pediatric to adult care is a critical milestone in managing children, especially in those with complex chronic conditions. It involves ensuring the patient and family adapt correctly to the new phase, maintaining continuity of ongoing treatments, and establishing an appropriate follow-up plan with specialists. Patients with Inborn error of immunity (IEI), formerly known as Primary Immune Disorders (PID) are part of a group of disorders characterized by alterations in the proper functioning of the immune system; as the diagnostic and treatment tools for these entities progress, life expectancy increases, and new needs emerge. These children have special needs during the transition. Particularly important in the group of children with PID and syndromic features, who often present multiple chronic medical conditions. In these cases, transition planning is a significant challenge, involving not only the patients and their families but also a wide range of specialists. To achieve this, a multidisciplinary transition team should be established between the pediatric specialists and the adult consultants, designing a circuit in which communication is essential. As few transition care guidelines in the field of PID are available, and to our knowledge, there is no specific information available regarding patients with PID associated with syndromic features, we share our experience in this issue as a Primary Immunodeficiencies Unit that is a National Reference Center for PID, and propose a guide to achieve an adequate and successful transition to adulthood in these patients, especially in those with associated syndromic features.

Clinical Course and Outcome of Prenatally Detected 22q11.2 Deletion Syndrome-A Retrospective Analysis

The 22q11.2 deletion syndrome (22q11.2 DS) is known as the most common microdeletion syndrome. Due to its variable clinical phenotype, prenatal diagnosis can be challenging. The aim of this retrospective study was to evaluate the clinical course and pregnancy outcome of cases with prenatally diagnosed 22q11.2 deletion syndrome (DS) as well as to evaluate the role of prenatal magnetic resonance imaging (MRI) and postmortem examination. In total, 21 cases who underwent prenatal ultrasound examination and pregnancy care at the Department of Obstetrics and Gynecology at the Medical University of Vienna between 2012 and 2022 were included. The majority of the cases were genetically diagnosed using fluorescent in situ hybridization (FISH). The median gestational age (GA) at genetic diagnosis was 23.0 weeks (IQR 21.4-24.8 weeks). CHDs were detected in all fetuses and the most common extracardiac manifestation was thymus hypo/aplasia followed by genitourinary anomalies. Prenatal magnetic resonance imaging (MRI) revealed additional diagnostic information in three of ten cases. Overall, 14 patients opted for drug-induced TOP, of which 9 cases had a feticide prior to the induction of labor. The majority of craniofacial malformations were only detected by autopsy. In conclusion, the majority of cases prenatally diagnosed with 22q11.2 DS had an absent or hypoplastic thymus noted antenatally in addition to the detected CHD, and almost half of the cases had another extracardiac malformation of predominantly genitourinary origin. Furthermore, prenatal MRIs confirmed previously detected malformations, but only provided additional diagnostic information in three out of ten cases, whereas postmortem examination diagnosed most of the craniofacial anomalies and should always be conducted, serving as an important quality indicator for prenatal imaging.

Analyses of thymocyte commitment to regulatory T cell lineage in thymus of healthy subjects and patients with 22q11.2 deletion syndrome

The Chromosome 22q11.2 deletion syndrome (22q11.2DS) results in an inborn error of immunity due to defective thymic organogenesis. Immunological abnormalities in 22q11.2DS patients are thymic hypoplasia, reduced output of T lymphocytes by the thymus, immunodeficiency and increased incidence of autoimmunity. While the precise mechanism responsible for increased incidence of autoimmunity is not completely understood, a previous study suggested a defect in regulatory T cells (Treg) cell lineage commitment during T cell development in thymus. Here, we aimed to analyze this defect in more detail. Since Treg development in human is still ill-defined, we first analyzed where Treg lineage commitment occurs. We performed systematic epigenetic analyses of the Treg specific demethylation region (TSDR) of the FOXP3 gene in sorted thymocytes at different developmental stages. We defined CD3+CD4+CD8+ FOXP3+CD25+ as the T cell developmental stage in human where TSDR demethylation first occurs. Using this knowledge, we analyzed the intrathymic defect in Treg development in 22q11.2DS patients by combination of TSDR, CD3, CD4, CD8 locus epigenetics and multicolor flow cytometry. Our data showed no significant differences in Treg cell frequencies nor in their basic phenotype. Collectively, these data suggest that although 22q11.2DS patients present with reduced thymic size and T cell output, the frequencies and the phenotype of Treg cell at each developmental stage are surprisingly well preserved.

Neuroinflammation and Oxidative Stress in Individuals Affected by DiGeorge Syndrome

DiGeorge syndrome (DGS) is a rare genetic disease caused by microdeletions of the 22q11.2 region (DGS1). A haploinsufficiency at 10p level has been proposed also as a DGS cause (DGS2). Clinical manifestations are variable. The most frequent features are thymic hypoplasia or aplasia with consequent immune deficiency, cardiac malformations, hypoparathyroidism, facial and palatine abnormalities, variable degrees of cognitive impairment and psychiatric disorders. The specific aim of this descriptive report is to discuss the correlation between oxidative stress and neuroinflammation in DGS patients with microdeletions of the 22q11.2 region. The deleted chromosomic region maps various genes involved in mitochondrial metabolisms, such as DGCR8 and TXNRD2, that could lead to reactive oxygen species (ROS) increased production and antioxidant depletion. Furthermore, increased levels of ROS in mitochondria would lead to the destruction of the projection neurons in the cerebral cortex with consequent neurocognitive impairment. Finally, the increase in modified protein belonging to the family of sulfoxide compounds and hexoses, acting as inhibitors of the IV and V mitochondria complex, could result in direct ROS overproduction. Neuroinflammation in DGS individuals could be directly related to the development of the syndrome's characteristic psychiatric and cognitive disorders. In patients with psychotic disorders, the most frequent psychiatric manifestation in DGS, Th-17, Th-1 and Th-2 cells are increased with consequent elevation of proinflammatory cytokine IL-6 and IL1β. In patients with anxiety disorders, both CD3 and CD4 are increased. Some patients with autism spectrum disorders (ASDs) have an augmented level of proinflammatory cytokines IL-12, IL-6 and IL-1β, while IFNγ and the anti-inflammatory cytokine IL-10 seem to be reduced. Other data proposed that altered synaptic plasticity could be directly involved in DGS cognitive disorders. In conclusion, the use of antioxidants for restoring mitochondrial functionality in DGS could be a useful tool to protect cortical connectivity and cognitive behavior.

Inhibition of Abl Kinase by Imatinib Can Rescue the Compromised Barrier Function of 22q11.2DS Patient-iPSC-Derived Blood-Brain Barriers

We have previously established that the integrity of the induced blood-brain barrier (iBBB) formed by brain microvascular endothelial cells derived from the iPSC of 22q11.2 DS (22q11.2 Deletion Syndrome, also called DiGeorge Syndrome) patients is compromised. We tested the possibility that the haploinsufficiency of CRKL, a gene within the 22q11.2 DS deletion region, contributes to the deficit. The CRKL is a major substrate of the Abl tyrosine kinase, and the Abl/CRKL signaling pathway is critical for endothelial barrier functions. Imatinib, an FDA-approved drug, inhibits Abl kinase and has been used to treat various disorders involving vascular leakages. To test if imatinib can restore the compromised iBBB, we treated the patient's iBBB with imatinib. After treatment, both trans-endothelial electrical resistance and solute permeability returned to comparable levels of the control iBBB. Correspondingly, changes in tight junctions and endothelial glycocalyx of the iBBB were also restored. Western blotting showed that imatinib increased the level of active forms of the CRKL protein. A transcriptome study revealed that imatinib up-regulated genes in the signaling pathways responsible for the protein modification process and down-regulated those for cell cycling. The KEGG pathway analysis further suggested that imatinib improved the gene expression of the CRKL signaling pathway and tight junctions, which agrees with our expectations and the observations at protein levels. Our results indicate that the 22q11.2DS iBBB is at least partially caused by the haploinsufficiency of CRKL, which can be rescued by imatinib via its effects on the Abl/CRKL signaling pathway. Our findings uncover a novel disease mechanism associated with 22q11.2DS.

Environmental Influences on the Relation between the 22q11.2 Deletion Syndrome and Mental Health: A Literature Review

22q11.2 deletion syndrome (22q11DS) is a clinically heterogeneous genetic syndrome, associated with a wide array of neuropsychiatric symptoms. The clinical presentation is likely to be influenced by environmental factors, yet little is known about this. Here, we review the available research literature on the role of the environment in 22q11DS. We find that within-patient design studies have mainly investigated the role of parental factors, stress, and substance use, reporting significant effects of these factors on the clinical profile. Case-control studies have been less successful, with almost no reports of significant moderating effects of the environment. We go on to hypothesize which specific environmental measures are most likely to interact with the 22q11 deletion, based on the genes in this region and their involvement in molecular pathways. We end by discussing potential reasons for the limited findings so far, including modest sample sizes and limited availability of environmental measures, and make recommendations how to move forward.

Screening Method for 22q11 Deletion Syndrome Involving the Use of TaqMan qPCR for TBX1 in Patients with Conotruncal Congenital Heart Disease

22q11.2 deletion syndrome is a phenotypic spectrum that encompasses DiGeorge syndrome (OMIM: 188400) and velocardiofacial syndrome (OMIM: 192430). It is caused by a 1.5–3.0 Mb hemizygous deletion of locus 22q11.2, which leads to characteristic facies, conotruncal cardiovascular malformations, velopharyngeal insufficiency, T-lymphocyte dysfunction due to thymic aplasia, and parathyroid hypoplasia, and, less frequently, neurological manifestations such as delayed psychomotor development or schizophrenia. This study aimed to describe a screening method for the diagnosis of 22q11.2 deletion syndrome in patients with Conotruncal Congenital Heart Disease (CCHD), using qPCR to detect the copy number of the TBX1 gene in a single DNA sample. A total of 23 patients were included; 21 with a biallelic prediction of the TBX1 copy number gene and 2 with a monoallelic prediction who were suspected to be positive and subjected to MLPA confirmation. One patient (4.34%) with truncus arteriosus CCHD was confirmed to have 22q11.2 deletion syndrome. We propose this approach as a possible newborn screening method for 22q11.2 deletion syndrome in CCHD patients.

Crossed pulmonary arteries: An underestimated cardiovascular variant with a strong association with genetic syndromes-A report of 74 cases with systematic review of the literature

Crossed pulmonary arteries (CPAs) represent an uncommon anatomic variant, usually associated with some specific syndromes and conotruncal defects. This finding has been described in 22q11.2 Deletion Syndrome (22q11.2DS). We evaluated the correlation between CPAs and genetic diseases, in order to better define the characteristics of this variant, considered a rare anatomic pattern. An in-depth analysis of CPAs genotype-phenotype correlations was performed via a literature review. We detected 74 CPAs patients through echocardiography. Of these 74 patients, 35.1% of patients showed additional intracardiac malformations, while 29.7% showed extracardiac vascular anomalies, of which 16.2% were associated with intracardiac defects and 13.5% were not. In all, 62.2% of patients were diagnosed with genetic diseases and 52.2% of them were 22q11.2DS patients. In conclusions, CPAs represent a cardiovascular variant, which is detectable in nonsyndromic individuals, but especially in various genetic syndromes and in particular in 22q11.2DS patients. Data on the real prevalence of this morphology is lacking in literature. Knowledge of this anatomic variant is useful to interpret the unusual course of the pulmonary branches and is helpful information before cardiovascular surgical correction. Moreover, due to the strong association of CPAs with some genetic syndromes, the identification of this anatomic pattern can indicate the utility of a genetic assessment of these patients.

Congenital portosystemic venous shunt associated with 22q11.2 deletion syndrome: a case report

Background

22q11.2 deletion syndrome (22qDS) is the most common chromosomal microdeletion syndrome and is associated with a high rate of congenital heart disease (CHD) and neurodevelopmental abnormalities. Congenital portosystemic venous shunts (CPSS) are rare developmental abnormalities of the portal venous system. The clinical manifestations of CPSS are varied, and some patients have CHD or genetic chromosomal abnormalities, but their relationship remains unknown. We report the first case of CPSS associated with 22qDS.

Case presentation

A newborn boy referred to our institution was diagnosed with 22qDS due to characteristic facial features and complications of tetralogy of Fallot. A subsequent newborn screening test indicated hypergalactosemia and high blood levels of ammonia and bile acids. Upon closer examination, these abnormalities were found to be caused by the CPSS. Abdominal contrast-enhanced computed tomography and angiography confirmed that abnormal blood vessels ascended from the splenic vein and short-circuited to the left renal vein. Intracardiac repair for CHD was performed at 1 year of age, followed by transcatheter occlusion of the CPSS using a multilayer device (vascular plug) and detachable coil at 2 years of age. After treatment, the abnormal blood parameters promptly normalized.

Conclusions

As the blood flow of CPSS bypasses the liver, the levels of galactose, bile acids, and ammonia in the systemic veins can increase. Some patients with CPSS have CHD, and these toxic substances may cause liver and lung lesions as well as portosystemic encephalopathy (PSE). Several genetic chromosomal abnormalities, including 22qDS, and CPSS have similar symptoms, and neurodevelopmental abnormalities, particularly those caused by PSE, may be difficult to diagnose. Blood tests, such as newborn screening, and abdominal imaging are useful in the early diagnosis of CPSS.

Late maternal diagnosis of DiGeorge syndrome with congenital hypoparathyroidism following antenatal detection of the same 22q11.2 microdeletion syndrome in the fetus

Genetic causes of hypocalcaemia can be overlooked in patients who present without apparent syndromic features. One relatively common but under-recognised genetic disorder is DiGeorge syndrome, which is often diagnosed in childhood but rarely in adulthood. Its enigmatic diagnosis can be attributed to its broad heterogeneous clinical presentation, such as the absence of cardiac abnormalities with only subtly abnormal facies. The presence of hypoparathyroidism-related hypocalcaemia may be the first early sign. We describe a young female adult with childhood-onset hypocalcaemia who was diagnosed with DiGeorge syndrome during her pregnancy when the fetus was found to have the same condition on antenatal screening and autopsy. This case reminds clinicians to consider the genetic causes of hypoparathyroidism-induced hypocalcaemia early on in childhood, while acknowledging the possibility of a late diagnosis in adulthood. We also highlight the risks of severe hypocalcaemia in pregnancy and outline a systematic approach to the evaluation of chronic hypocalcaemia.

Establishment of a Dihydrofolate Reductase Gene Knock-In Zebrafish Strain to Aid Preliminary Analysis of Congenital Heart Disease Mechanisms

Background: The dihydrofolate reductase (DHFR) gene is imperative in development, therefore it is essential to explore its effects on heart development. Thus, here a dhfr zebrafish knock-in (KI) strain was constructed.

Methods: CRISPR/Cas9 technology was used to establish the dhfr KI zebrafish strain. This strain was hybridized with TgG fluorescent strain zebrafish to observe the phenotypes of heart shape, size, and circularization direction. Wild-type (WT) and KI zebrafish were then dissected and histologically stained to observe pathological changes. Western blot analysis was used to verify the increased expressions of zebrafish genes after KI. Hybridization experiments were used to confirm the presence of abnormal gonadal dysplasia.

Results: The zebrafish dhfr KI strain was successfully constructed through CRISPR/Cas9 technology. At 6 days post fertilization (dpf), microscopic examinations of KI (homozygous) specimens revealed pericardial effusions, heart compressions, and curled tails. Compared with WT, the Hematoxylin and Eosin (H&E) tissue sections of KI-homozygous zebrafish showed defects such as reduced atria and ventricles. Western blot analysis indicated that the expression of the DHFR protein increased in both heterozygotes and homozygotes of dhfr KI zebrafish. Hybridization experiments revealed that dhfr KI may affect gonadal function.

Conclusion: The DHFR gene plays an important regulatory role in the process of heart development, and copy number variations (CNVs) of this gene may constitute a new pathogenic mechanism of congenital heart disease (CHD).