Partial Jacobsen syndrome phenotype in a patient with a de novo frameshift mutation in the ETS1 transcription factor

Prenatal diagnosis of Jacobsen syndrome associated with a distal 11q deletion and a distal 8q duplication by chromosome microarray analysis in a fetus with a de novo unbalanced translocation of 46,XX,der(11)t(8;11)(q24.13;q23.3) and multiple congenital anomalies on fetal ultrasound

OBJECTIVE

We present prenatal diagnosis of Jacobsen syndrome associated with a distal 11q deletion and a distal 8q duplication by chromosome microarray analysis (CMA) in a fetus with multiple congenital anomalies on fetal ultrasound.

CASE REPORT

A 41-year-old, gravida 2, para 1, woman underwent amniocentesis at 25 weeks of gestation because of intrauterine growth restriction, endocardial cushion defect, clenched hands, arthrogryposis, rocker bottom feet and craniosynostosis on fetal ultrasound. Amniocentesis revealed a karyotype of 46,XX,add(11)(q23.3). Array comparative genomic hybridization (aCGH) analysis of the DNA extracted from the uncultured amniocytes revealed the result of arr 8q24.13q24.3 × 3, 11q23.3q25 × 1. Analysis of FGFR2 revealed no mutation. The karyotype was 46,XX,der(11)t(8;11)(q24.13;q23.3). The parental karyotypes were normal. The pregnancy was subsequently terminated, and a dead malformed fetus was delivered with craniofacial dysmorphism of low-set malformed ears, depressed nasal bridge, hypertelorism, small mouth, clenched hands and rocker bottom feet. Cytogenetic analysis of the placenta revealed a karyotype of 46,XX,der(11)t(8;11)(q24.13;q23.3). aCGH analysis of the DNA extracted from the umbilical cord showed the result of arr 8q24.13q24.3 (126,302,369-146,280,020) × 3.0, arr 11q23.3q25 (120,469,928-134,868,407) × 1.0 [GRCh37] with a 19.978-Mb duplication of 8q24.13-q24.3 and a 14.398-Mb deletion of 11q23.3-q25 encompassing the genes of BSX, ETS1, FLI1 and ARHGAP32.

CONCLUSION

CMA is useful for detection of de novo chromosomal rearrangement in the fetus with multiple congenital anomalies on fetal ultrasound.

Changes in effective connectivity during the visual-motor integration tasks: a preliminary f-NIRS study

BACKGROUND

Visual-motor integration (VMI) is an essential skill in daily life. The present study aimed to use functional near-infrared spectroscopy (fNIRS) technology to explore the effective connectivity (EC) changes among brain regions during VMI activities of varying difficulty levels.

METHODS

A total of 17 healthy participants were recruited for the study. Continuous Performance Test (CPT), Behavior Rating Inventory of Executive Function-Adult Version (BRIEF-A), and Beery VMI test were used to evaluate attention performance, executive function, and VMI performance. Granger causality analysis was performed for the VMI task data to obtain the EC matrix for all participants. One-way ANOVA analysis was used to identify VMI load-dependent EC values among different task difficulty levels from brain network and channel perspectives, and partial correlation analysis was used to explore the relationship between VMI load-dependent EC values and behavioral performance.

RESULTS

We found that the EC values of dorsal attention network (DAN) → default mode network (DMN), DAN → ventral attention network (VAN), DAN → frontoparietal network (FPN), and DAN → somatomotor network (SMN) in the complex condition were higher than those in the simple and moderate conditions. Further channel analyses indicated that the EC values of the right superior parietal lobule (SPL) → right superior frontal gyrus (SFG), right middle occipital gyrus (MOG) → left SFG, and right MOG → right postcentral gyrus (PCG) in the complex condition were higher than those in the simple and moderate conditions. Subsequent partial correlation analysis revealed that the EC values from DAN to DMN, VAN, and SMN were positively correlated with executive function and VMI performance. Furthermore, the EC values of right MOG → left SFG and right MOG → right PCG were positively correlated with attention performance.

CONCLUSIONS

The DAN is actively involved during the VMI task and thus may play a critical role in VMI processes, in which two key brain regions (right SPL, right MOG) may contribute to the EC changes in response to increasing VMI load. Meanwhile, bilateral SFG and right PCG may also be closely related to the VMI performance.

Fragile sites, chromosomal lesions, tandem repeats, and disease

Expanded tandem repeat DNAs are associated with various unusual chromosomal lesions, despiralizations, multi-branched inter-chromosomal associations, and fragile sites. Fragile sites cytogenetically manifest as localized gaps or discontinuities in chromosome structure and are an important genetic, biological, and health-related phenomena. Common fragile sites (∼230), present in most individuals, are induced by aphidicolin and can be associated with cancer; of the 27 molecularly-mapped common sites, none are associated with a particular DNA sequence motif. Rare fragile sites ( ≳ 40 known), ≤ 5% of the population (may be as few as a single individual), can be associated with neurodevelopmental disease. All 10 molecularly-mapped folate-sensitive fragile sites, the largest category of rare fragile sites, are caused by gene-specific CGG/CCG tandem repeat expansions that are aberrantly CpG methylated and include FRAXA, FRAXE, FRAXF, FRA2A, FRA7A, FRA10A, FRA11A, FRA11B, FRA12A, and FRA16A. The minisatellite-associated rare fragile sites, FRA10B, FRA16B, can be induced by AT-rich DNA-ligands or nucleotide analogs. Despiralized lesions and multi-branched inter-chromosomal associations at the heterochromatic satellite repeats of chromosomes 1, 9, 16 are inducible by de-methylating agents like 5-azadeoxycytidine and can spontaneously arise in patients with ICF syndrome (Immunodeficiency Centromeric instability and Facial anomalies) with mutations in genes regulating DNA methylation. ICF individuals have hypomethylated satellites I-III, alpha-satellites, and subtelomeric repeats. Ribosomal repeats and subtelomeric D4Z4 megasatellites/macrosatellites, are associated with chromosome location, fragility, and disease. Telomere repeats can also assume fragile sites. Dietary deficiencies of folate or vitamin B12, or drug insults are associated with megaloblastic and/or pernicious anemia, that display chromosomes with fragile sites. The recent discovery of many new tandem repeat expansion loci, with varied repeat motifs, where motif lengths can range from mono-nucleotides to megabase units, could be the molecular cause of new fragile sites, or other chromosomal lesions. This review focuses on repeat-associated fragility, covering their induction, cytogenetics, epigenetics, cell type specificity, genetic instability (repeat instability, micronuclei, deletions/rearrangements, and sister chromatid exchange), unusual heritability, disease association, and penetrance. Understanding tandem repeat-associated chromosomal fragile sites provides insight to chromosome structure, genome packaging, genetic instability, and disease.

GATA4 Regulates Developing Endocardium Through Interaction With ETS1

BACKGROUND

The pioneer transcription factor (TF) GATA4 (GATA Binding Protein 4) is expressed in multiple cardiovascular lineages and is essential for heart development. GATA4 lineage-specific occupancy in the developing heart underlies its lineage specific activities. Here, we characterized GATA4 chromatin occupancy in cardiomyocyte and endocardial lineages, dissected mechanisms that control lineage specific occupancy, and analyzed GATA4 regulation of endocardial gene expression.

METHODS

We mapped GATA4 chromatin occupancy in cardiomyocyte and endocardial cells of embryonic day 12.5 (E12.5) mouse heart using lineage specific, Cre-activated biotinylation of GATA4. Regulation of GATA4 pioneering activity was studied in cell lines stably overexpressing GATA4. GATA4 regulation of endocardial gene expression was analyzed using single cell RNA sequencing and luciferase reporter assays.

RESULTS

Cardiomyocyte-selective and endothelial-selective GATA4 occupied genomic regions had features of lineage specific enhancers. Footprints within cardiomyocyte- and endothelial-selective GATA4 regions were enriched for NKX2-5 (NK2 homeobox 5) and ETS1 (ETS Proto-Oncogene 1) motifs, respectively, and both of these TFs interacted with GATA4 in co-immunoprecipitation assays. In stable NIH3T3 cell lines expressing GATA4 with or without NKX2-5 or ETS1, the partner TFs re-directed GATA4 pioneer binding and augmented its ability to open previously inaccessible regions, with ETS1 displaying greater potency as a pioneer partner than NKX2-5. Single-cell RNA sequencing of embryonic hearts with endothelial cell-specific Gata4 inactivation identified Gata4-regulated endocardial genes, which were adjacent to GATA4-bound, endothelial regions enriched for both GATA4 and ETS1 motifs. In reporter assays, GATA4 and ETS1 cooperatively stimulated endothelial cell enhancer activity.

CONCLUSIONS

Lineage selective non-pioneer TFs NKX2-5 and ETS1 guide the activity of pioneer TF GATA4 to bind and open chromatin and create active enhancers and mechanistically link ETS1 interaction to GATA4 regulation of endocardial development.

Case report: ETS1 gene deletion associated with a low number of recent thymic emigrants in three patients with Jacobsen syndrome

Jacobsen syndrome is a rare genetic disorder associated with a terminal deletion in chromosome 11. The clinical presentation is variable. Although immunodeficiency has been described in patients with Jacobsen syndrome, a clear genotype-phenotype correlation has not yet been established. Here, we report on the immunologic phenotypes of four patients with Jacobsen syndrome. All four patients showed one or more atypical immunologic features. One patient suffered from recurrent viral infections, two patients had experienced a severe bacterial infection and one had received antibiotic prophylaxis since early childhood. One patient had experienced severe, transient immune dysregulation. Hypogammaglobulinemia and low B cell counts were found in two patients, while the number of recent thymic emigrants (CD31+CD45RA+ CD4 cells) was abnormally low in three. When considering the six immune-related genes located within the affected part of chromosome 11 (ETS1, TIRAP, FLI1, NFRKB, THYN1, and SNX19), only the ETS1 gene was found be deleted in the three patients with low numbers of recent thymic emigrants and non-switched memory B cells. Our findings support the hypothesis whereby Jacobsen syndrome is associated with a combined immunodeficiency with variable presentation. Further investigations of potential genotype-phenotype correlations are warranted and might help to personalize patient management in individuals lacking immune-related genes. In addition, we recommend immunologic follow-up for all patients with Jacobsen syndrome, as immune abnormalities may develop over time.

Endothelial Loss of ETS1 Impairs Coronary Vascular Development and Leads to Ventricular Non-Compaction

RATIONALE

Jacobsen syndrome is a rare chromosomal disorder caused by deletions in the long arm of human chromosome 11, resulting in multiple developmental defects including congenital heart defects. Combined studies in humans and genetically engineered mice implicate that loss of ETS1 (E26 transformation specific 1) is the cause of congenital heart defects in Jacobsen syndrome, but the underlying molecular and cellular mechanisms are unknown.

OBJECTIVE

To determine the role of ETS1 in heart development, specifically its roles in coronary endothelium and endocardium and the mechanisms by which loss of ETS1 causes coronary vascular defects and ventricular noncompaction.

METHODS AND RESULTS

ETS1 global and endothelial-specific knockout mice were used. Phenotypic assessments, RNA sequencing, and chromatin immunoprecipitation analysis were performed together with expression analysis, immunofluorescence and RNAscope in situ hybridization to uncover phenotypic and transcriptomic changes in response to loss of ETS1. Loss of ETS1 in endothelial cells causes ventricular noncompaction, reproducing the phenotype arising from global deletion of ETS1. Endothelial-specific deletion of ETS1 decreased the levels of Alk1 (activin receptor-like kinase 1), Cldn5 (claudin 5), Sox18 (SRY-box transcription factor 18), Robo4 (roundabout guidance receptor 4), Esm1 (endothelial cell specific molecule 1) and Kdr (kinase insert domain receptor), 6 important angiogenesis-relevant genes in endothelial cells, causing a coronary vasculature developmental defect in association with decreased compact zone cardiomyocyte proliferation. Downregulation of ALK1 expression in endocardium due to the loss of ETS1, along with the upregulation of TGF (transforming growth factor)-β1 and TGF-β3, occurred with increased TGFBR2/TGFBR1/SMAD2 signaling and increased extracellular matrix expression in the trabecular layer, in association with increased trabecular cardiomyocyte proliferation.

CONCLUSIONS

These results demonstrate the importance of endothelial and endocardial ETS1 in cardiac development. Delineation of the gene regulatory network involving ETS1 in heart development will enhance our understanding of the molecular mechanisms underlying ventricular and coronary vascular developmental defects and will lead to improved approaches for the treatment of patients with congenital heart disease.

Patients with Chromosome 11q Deletions Are Characterized by Inborn Errors of Immunity Involving both B and T Lymphocytes

Disorders of the long arm of chromosome 11 (11q) are rare and involve various chromosomal regions. Patients with 11q disorders, including Jacobsen syndrome, often present with a susceptibility for bacterial and prolonged viral and fungal infections partially explained by hypogammaglobulinemia. Additional T lymphocyte or granular neutrophil dysfunction may also be present. In order to evaluate infectious burden and immunological function in patients with 11q disorders, we studied a cohort of 14 patients with 11q deletions and duplications. Clinically, 12 patients exhibited prolonged and repetitive respiratory tract infections, frequently requiring (prophylactic) antibiotic treatment (n = 7), ear-tube placement (n = 9), or use of inhalers (n = 5). Complicated varicella infections (n = 5), chronic eczema (n = 6), warts (n = 2), and chronic fungal infections (n = 4) were reported. Six patients were on immunoglobulin replacement therapy. We observed a high prevalence of low B lymphocyte counts (n = 8), decreased T lymphocyte counts (n = 5) and abnormal T lymphocyte function (n = 12). Granulocyte function was abnormal in 29% without a clinical phenotype. Immunodeficiency was found in patients with terminal and interstitial 11q deletions and in one patient with terminal 11q duplication. Genetically, FLI1 and ETS1 are seen as causative for the immunodeficiency, but these genes were deleted nor duplicated in 4 of our 14 patients. Alternative candidate genes on 11q may have a role in immune dysregulation. In conclusion, we present evidence that inborn errors of immunity are present in patients with 11q disorders leading to clinically relevant infections. Therefore, broad immunological screening and necessary treatment is of importance in this patient group.

Hematological indices in pediatric patients with acyanotic congenital heart disease: a cross-sectional study of 248 patients

BACKGROUND

Congenital heart disease CHD is a significant cause of mortality and morbidity in children worldwide. Patients with congenital heart disease may develop hematological problems, including thrombocytopenia and neutropenia. In addition, several studies indicate the higher frailty of patients with CHDs to infections and malignancies. Nevertheless, the mechanisms of immune system changes in these patients have remained in the shadow of uncertainty. Moreover, very few studies have worked on cytopenia in CHD. This study has assessed the frequency of thrombocytopenia, neutropenia, lymphopenia, and anemia in pediatric patients with acyanotic congenital heart disease ACHD prior to open-heart surgery.

METHODS

This cross-sectional study was handled in the Pediatric Cardiology Clinic, Tehran University of Medical Sciences, during pre-operation visits from 2014 till 2019. Two hundred forty-eight children and adolescents with acyanotic congenital heart disease before open-heart surgery met the criteria to enter the study.

RESULTS

A total of 191 (76.7%) patients with Ventricular Septal Defects (VSD), 37 (14.85%) patients with Atrial Septal Defects (ASD), and 20 (8.11%) patients with Patent Ductus Arteriosus (PDA) were enrolled in this study. The median age was 23.87 months. Thrombocytopenia and neutropenia were found, respectively, in 3 (1.2) and 23 (9.2%) patients. Hemoglobin level and lymphocyte count were significantly lower in patients with neutropenia than patients with normal neutrophil count (P value = 0.024 and P value = 0.000). Significant positive correlations were found between neutropenia and anemia. There were no correlations between neutrophil count and Platelets. Also, anemia was found in 48 patients (19.3%). The study also found a statistically significant correlation between the co-existence of VSD and neutropenia in the patients (P value = 0.000).

CONCLUSION

Although most were mildly neutropenic, there was a significant correlation between neutropenia and Ventricular Septal Defect compared to PDA and ASD groups. Regarding the importance of neutropenia to affect the prognosis of congenital heart defects in infections, it is important to consider further studies on the status of immune system function in these patients.

Immunological Evaluation of Patients Affected with Jacobsen Syndrome Reveals Profound Not Age-Related Lymphocyte Alterations

PURPOSE

Jacobsen syndrome (JS) is a rare form of genetic disorder that was recently classified as a syndromic immunodeficiency. Available detailed immunological data from JS patients are limited.

METHODS

Clinical and immunological presentation of twelve pediatric patients with JS by means of revision of clinical records, flow cytometry, real-time PCR, and lymphocyte functional testing were collected.

RESULTS

Recurrent infections were registered in 6/12 patients (50%), while bleeding episodes in 2/12 (16.7%). White blood cell and absolute lymphocyte counts were reduced in 8/12 (66.7%) and 7/12 (58.3%) patients, respectively. Absolute numbers of CD3⁺ and CD4⁺ T cells were reduced in 8/12 (66.7%) and 7/12 (58.3%), respectively. Of note, recent thymic emigrants (RTE) were reduced in all tested patients (9/9), with T-cell receptor excision circle analysis (TRECs) showing a similar trend in 8/9 patients; naïve CD4⁺ T cells were low only in 5/11 patients (45.4%). Interestingly, B-cell counts, IgM memory B cells, and IgM serum levels were reduced in 10/12 (83.3%) patients. Natural killer (NK) cell counts were mostly normal but the percentages of CD16⁺CD56^low/- cells were expanded in 7/7 patients tested. The observed immunological alterations did not correlate with patients' age. Finally, responses to proliferative stimuli were normal at presentation for all patients, although they may deteriorate over time.

CONCLUSIONS

Our data suggest that patients affected with JS may display important numeric and maturational alterations in the T-, B-, and NK-cell compartments. These findings suggest that JS patients should be regularly monitored from an immunological point of view.

Jacobsen syndrome and neonatal bleeding: report on two unrelated patients

Introduction

In 1973, Petrea Jacobsen described the first patient showing dysmorphic features, developmental delay and congenital heart disease (atrial and ventricular septal defect) associated to a 11q deletion, inherited from the father. Since then, more than 200 patients have been reported, and the chromosomal critical region responsible for this contiguous gene disorder has been identified.

Patients’ presentation

We report on two unrelated newborns observed in Italy affected by Jacobsen syndrome (JBS, also known as 11q23 deletion). Both patients presented prenatal and postnatal bleeding, growth and developmental delay, craniofacial dysmorphisms, multiple congenital anomalies, and pancytopenia of variable degree. Array comparative genomic hybridization (aCGH) identified a terminal deletion at 11q24.1-q25 of 12.5 Mb and 11 Mb, in Patient 1 and 2, respectively. Fluorescent in situ hybridization (FISH) analysis of the parents documented a de novo origin of the deletion for Patient 1; parents of Patient 2 refused further genetic investigations.

Conclusions

Present newborns show the full phenotype of JBS including thrombocytopenia, according to their wide 11q deletion size. Bleeding was particularly severe in one of them, leading to a cerebral hemorrhage. Our report highlights the relevance of early diagnosis, genetic counselling and careful management and follow-up of JBS patients, which may avoid severe clinical consequences and lower the mortality risk. It may provide further insights and a better characterization of JBS, suggesting new elements of the genotype-phenotype correlations.

Focused Strategies for Defining the Genetic Architecture of Congenital Heart Defects

Congenital heart defects (CHD) are malformations present at birth that occur during heart development. Increasing evidence supports a genetic origin of CHD, but in the process important challenges have been identified. This review begins with information about CHD and the importance of detailed phenotyping of study subjects. To facilitate appropriate genetic study design, we review DNA structure, genetic variation in the human genome and tools to identify the genetic variation of interest. Analytic approaches powered for both common and rare variants are assessed. While the ideal outcome of genetic studies is to identify variants that have a causal role, a more realistic goal for genetic analytics is to identify variants in specific genes that influence the occurrence of a phenotype and which provide keys to open biologic doors that inform how the genetic variants modulate heart development. It has never been truer that good genetic studies start with good planning. Continued progress in unraveling the genetic underpinnings of CHD will require multidisciplinary collaboration between geneticists, quantitative scientists, clinicians, and developmental biologists.

Intrinsic Endocardial Defects Contribute to Hypoplastic Left Heart Syndrome

Hypoplastic left heart syndrome (HLHS) is a complex congenital heart disease characterized by abnormalities in the left ventricle, associated valves, and ascending aorta. Studies have shown intrinsic myocardial defects but do not sufficiently explain developmental defects in the endocardial-derived cardiac valve, septum, and vasculature. Here, we identify a developmentally impaired endocardial population in HLHS through single-cell RNA profiling of hiPSC-derived endocardium and human fetal heart tissue with an underdeveloped left ventricle. Intrinsic endocardial defects contribute to abnormal endothelial-to-mesenchymal transition, NOTCH signaling, and extracellular matrix organization, key factors in valve formation. Endocardial abnormalities cause reduced cardiomyocyte proliferation and maturation by disrupting fibronectin-integrin signaling, consistent with recently described de novo HLHS mutations associated with abnormal endocardial gene and fibronectin regulation. Together, these results reveal a critical role for endocardium in HLHS etiology and provide a rationale for considering endocardial function in regenerative strategies.

A three-tiered integrative analysis of transcriptional data reveals the shared pathways related to heart failure from different aetiologies

Heart failure (HF) is the end stage of most heart disease cases and can be initiated from multiple aetiologies. However, whether the molecular basis of HF has a commonality between different aetiologies has not been elucidated. To address this lack, we performed a three‐tiered analysis by integrating transcriptional data and pathway information to explore the commonalities of HF from different aetiologies. First, through differential expression analysis, we obtained 111 genes that were frequently differentially expressed in HF from 11 different aetiologies. Several genes, such as NPPA and NPPB, are early and accurate biomarkers for HF. We also provided candidates for further experimental verification, such as SERPINA3 and STAT4. Then, using gene set enrichment analysis, we successfully identified 19 frequently dysregulated pathways. In particular, we found that pathways related to immune system signalling, the extracellular matrix and metabolism were critical in the development of HF. Finally, we successfully acquired 241 regulatory relationships between 64 transcriptional factors (TFs) and 17 frequently dysregulated pathways by integrating a regulatory network, and some of the identified TFs have already been proven to play important roles in HF. Taken together, the three‐tiered analysis of HF provided a systems biology perspective on HF and emphasized the molecular commonality of HF from different aetiologies.