Recent genetic data suggest that abnormal cardiac development participates to the pathogenesis of Brugada Syndrome (BrS), a rare inherited arrhythmia responsible for sudden cardiac death in young ...adults. In vitro cardiac differentiation of human induced pluripotent stem cells (hiPSCs) mimics cardiac development at the cellular level up to a prenatal stage.
This study aims at defining whether BrS impairs cardiac differentiation of hiPSCs.
Single-cell transcriptomic data were generated at day 30 of in vitro cardiac differentiation of hiPSCs from 2 control subjects (n=6139 cells) and 2 BrS patients (n=13756 cells). These transcriptomic data have been annotated using public data obtained from human heart samples at 7.5 post conception weeks (PCW). In addition, bulk 3′RNA-seq data were generated in triplicate for 3 control hiPSC lines and 3 BrS-patient hiPSC lines at each day of the 30-day cardiac-directed differentiation protocol.
Single-cell data revealed (1) differences in cell type distribution, with BrS-hiPSCs and control-hiPSCs cardiac-directed differentiation generating 9.8% and 32.85% cardiomyocytes and 16.6% and 2.75% smooth muscle cells, respectively, and (2) cardiomyocytes transcriptomic alterations associated with biological processes of cardiac development, morphogenesis and conduction in BrS. Based on the finding, showing that BrS is associated with alterations in cardiac differentiation, we used the bulk transcriptomic kinetic data to analyze temporal transcriptomic alterations during cardiac-directed differentiation. Differential gene expression analysis unveiled (1) gene expression signatures specific to each BrS patients and (2) expression alterations that were common to all 3 BrS-hiPSCs lines as compared with control lines. Interestingly, the misexpressed genes were associated to the cell differentiation process (GO: 0030154) and their expression kinetics were altered during the cardiac differentiation process.
By generating and analyzing single-cell and bulk transcriptomic data during cardiac-directed differentiation of hiPSCs, this study strongly suggests that transcriptomic remodeling occurs as early as the cardiac development for BrS patients.
Objectives The aim of this study was to investigate, in a set of 93 mutation-negative long QT syndrome (LQTS) probands, the frequency of copy number variants (CNVs) in LQTS genes. Background LQTS is ...an inherited cardiac arrhythmia characterized by a prolonged heart rate–corrected QT (QTc) interval associated with sudden cardiac death. Recent studies suggested the involvement of duplications or deletions in the occurrence of LQTS. However, their frequency remains unknown in LQTS patients. Methods Point mutations in KCNQ1 , KCNH2 , and SCN5A genes were excluded by denaturing high-performance liquid chromatography or direct sequencing. We applied Multiplex Ligation-dependent Probe Amplification (MLPA) to detect CNVs in exons of these 3 genes. Abnormal exon copy numbers were confirmed by quantitative multiplex PCR of short fluorescent fragment (QMPSF). Array-based comparative genomic hybridization (array CGH) analysis was performed using Agilent Human Genome 244K Microarrays to further map the genomic rearrangements. Results We identified 3 different deletions in 3 unrelated families: 1 in KCNQ1 and 2 involving KCNH2 . We showed in the largest family that the deletion involving KCNH2 is fully penetrant and segregates with the long QT phenotype in 7 affected members. Conclusions Our study demonstrates that CNVs in KCNQ1 and KCNH2 explain around 3% of LQTS in patients with no point mutation in these genes. This percentage is likely higher than the frequency of point mutations in ANKB , KCNE1 , KCNE2 , KCNJ2 , CACNA1C , CAV3 , SCN4B , AKAP9 , and SNTA1 together. Thus, we propose that CNV screening in KCNQ1 and KCNH2 may be performed routinely in LQTS patients.
We performed whole-exome and whole-genome sequencing in 927 late-onset Alzheimer disease (LOAD) cases, 852 early-onset AD (EOAD) cases, and 1273 controls from France. We assessed the evidence for ...gene-based association of rare variants with AD in 6 genes for which an association with such variants was previously claimed. When aggregating protein-truncating and missense-predicted damaging variants, we found exome-wide significant association between EOAD risk and rare variants in SORL1, TREM2, and ABCA7. No exome-wide significant signal was obtained in the LOAD sample, and significance of the order of 10−6 was observed in the whole AD group for TREM2. Our study confirms previous gene-level results for TREM2, SORL1, and ABCA7 and provides a clearer insight into the classes of rare variants involved. Despite different effect sizes and varying cumulative minor allele frequencies, the rare protein-truncating and missense-predicted damaging variants in TREM2, SORL1, and ABCA7 contribute similarly to the heritability of EOAD and explain between 1.1% and 1.5% of EOAD heritability each, compared with 9.12% for APOE ε4.
Summary Detection of an intracranial aneurysm (IA) is a common finding in MRI practice. Nowadays, the incidence of unruptured IA seems to be increasing with the continuous evolution of imaging ...techniques. Important modifiable risk factors for SAH are well defined, but familial history of IA is the best risk marker for the presence of IA. Numerous heritable conditions are associated with IA formation but these syndromes account for less than 1% of all IAs in the population. No diagnostic test based on genetic knowledge is currently available to identify theses mutations and patients who are at higher risk for developing IAs. In the longer term, a more comprehensive understanding of independent and interdependent molecular pathways germane to IA formation and rupture may guide the physician in developing targeted therapies and optimizing prognostic risk assessment.
Chuvash polycythemia is an autosomal recessive form of erythrocytosis associated with a homozygous p.Arg200Trp mutation in the von Hippel-Lindau (VHL) gene. Since this discovery, additional VHL ...mutations have been identified in patients with congenital erythrocytosis, in a homozygous or compound-heterozygous state. VHL is a major tumor suppressor gene, mutations in which were first described in patients presenting with VHL disease, which is characterized by the development of highly vascularized tumors. Here, we identify a new VHL cryptic exon (termed E1′) deep in intron 1 that is naturally expressed in many tissues. More importantly, we identify mutations in E1′ in 7 families with erythrocytosis (1 homozygous case and 6 compound-heterozygous cases with a mutation in E1′ in addition to a mutation in VHL coding sequences) and in 1 large family with typical VHL disease but without any alteration in the other VHL exons. In this study, we show that the mutations induced a dysregulation of VHL splicing with excessive retention of E1′ and were associated with a downregulation of VHL protein expression. In addition, we demonstrate a pathogenic role for synonymous mutations in VHL exon 2 that altered splicing through E2-skipping in 5 families with erythrocytosis or VHL disease. In all the studied cases, the mutations differentially affected splicing, correlating with phenotype severity. This study demonstrates that cryptic exon retention and exon skipping are new VHL alterations and reveals a novel complex splicing regulation of the VHL gene. These findings open new avenues for diagnosis and research regarding the VHL-related hypoxia-signaling pathway.
•Mutations in a VHL cryptic exon may be found in patients with familial erythrocytosis or VHL disease.•Synonymous mutations in VHL exon 2 may induce exon skipping and cause familial erythrocytosis or VHL disease.
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Induced pluripotent stem cells (iPSCs) have considerably impacted human developmental biology and regenerative medicine, notably because they circumvent the use of cells of embryonic origin and offer ...the potential to generate patient-specific pluripotent stem cells. However, conventional reprogramming protocols produce developmentally advanced, or primed, human iPSCs (hiPSCs), restricting their use to post-implantation human development modeling. Hence, there is a need for hiPSCs resembling preimplantation naive epiblast. Here, we develop a method to generate naive hiPSCs directly from somatic cells, using OKMS overexpression and specific culture conditions, further enabling parallel generation of their isogenic primed counterparts. We benchmark naive hiPSCs against human preimplantation epiblast and reveal remarkable concordance in their transcriptome, dependency on mitochondrial respiration and X-chromosome status. Collectively, our results are essential for the understanding of pluripotency regulation throughout preimplantation development and generate new opportunities for disease modeling and regenerative medicine.
Pitt-Hopkins syndrome (PHS) is a rare syndromic encephalopathy characterized by daily bouts of hyperventilation and a facial gestalt. We report a 1.8-Mb de novo microdeletion on chromosome 18q21.1, ...identified by array–comparative genomic hybridization in one patient with PHS. We subsequently identified two de novo heterozygous missense mutations of a conserved amino acid in the basic region of the
TCF4 gene in three additional subjects with PHS. These findings demonstrate that
TCF4 anomalies are responsible for PHS and provide the first evidence of a human disorder related to class I basic helix-loop-helix transcription-factor defects (also known as “E proteins”). Moreover, our data may shed new light on the normal processes underlying autonomic nervous system development and maintenance of an appropriate ventilatory neuronal circuitry.
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•We propose a geometrical characterisation of cerebral tree bifurcations.•A 3D skeleton associated with a graph provide an accurate bifurcation localization.•We show a link between ...bifurcations’ geometry and the formation of aneurysms.•The bifurcation angles and the mother artery tortuosity plays important roles.•Geometrical estimations were compared with ground truth measurements.
An aneurysm is a vascular disorder where ballooning may form in a weakened section of the wall in the blood vessel. The swelling of the aneurysm may lead to its rupture. Intra-cranial aneurysms are the ones presenting the higher risks. If ruptured, the aneurysm may induce a subarachnoid haemorrhage which could lead to premature death or permanent disability. In this study, we are interested in locating and characterizing the bifurcations of the cerebral vascular tree. We use a 3D skeletonization combined with a graph-based approach to detect the bifurcations. In this work, we thus propose a full geometric characterisation of the bifurcations and related arteries. Aside from any genetic predisposition and environmental risk factors, the geometry of the brain vasculature may influence the chance of aneurysm formation. Among the main achievements, in this paper, we propose accurate, predictive 3D measurements of the bifurcations and we furthermore estimate the risk of occurrence of an aneurysm on a given bifurcation.
The Brugada syndrome (BrS) is a rare heritable cardiac arrhythmia disorder associated with ventricular fibrillation and sudden cardiac death. Mutations in the SCN5A gene have been causally related to ...BrS in 20-30% of cases. Twenty other genes have been described as involved in BrS, but their overall contribution to disease prevalence is still unclear. This study aims to estimate the burden of rare coding variation in arrhythmia-susceptibility genes among a large group of patients with BrS. We have developed a custom kit to capture and sequence the coding regions of 45 previously reported arrhythmia-susceptibility genes and applied this kit to 167 index cases presenting with a Brugada pattern on the electrocardiogram as well as 167 individuals aged over 65-year old and showing no history of cardiac arrhythmia. By applying burden tests, a significant enrichment in rare coding variation (with a minor allele frequency below 0.1%) was observed only for SCN5A, with rare coding variants carried by 20.4% of cases with BrS versus 2.4% of control individuals (P = 1.4 × 10(-7)). No significant enrichment was observed for any other arrhythmia-susceptibility gene, including SCN10A and CACNA1C. These results indicate that, except for SCN5A, rare coding variation in previously reported arrhythmia-susceptibility genes do not contribute significantly to the occurrence of BrS in a population with European ancestry. Extreme caution should thus be taken when interpreting genetic variation in molecular diagnostic setting, since rare coding variants were observed in a similar extent among cases versus controls, for most previously reported BrS-susceptibility genes.
In first-degree relatives of patients with aneurysmal subarachnoid hemorrhage (aSAH), the risk of an intracranial aneurysm can be predicted at initial screening but not at follow-up screening. We ...aimed to develop a model for predicting the probability of a new intracranial aneurysm after initial screening in people with a positive family history of aSAH.
In a prospective study, we obtained data from follow-up screening for aneurysms of 499 subjects with ≥2 affected first-degree relatives. Screening took place at the University Medical Center Utrecht, the Netherlands, and the University Hospital of Nantes, France. We studied associations between potential predictors and the presence of aneurysms using Cox regression analysis and the predictive performance at 5, 10, and 15 years after initial screening using C statistics and calibration plots, while correcting for overfitting.
In 5050 person-years of follow-up, intracranial aneurysms were found in 52 subjects. The risk of aneurysm at 5 years was 2% to 12%, at 10 years, 4% to 28%, and at 15 years, 7% to 40%. Predictors were female sex, history of intracranial aneurysms/aneurysmal subarachnoid hemorrhage, and older age. The sex, previous history of intracranial aneurysm/aSAH, older age score had a C statistic of 0.70 (95% CI, 0.61-0.78) at 5 years, 0.71 (95% CI, 0.64-0.78) at 10 years, and 0.70 (95% CI, 0.63-0.76) at 15 years and showed good calibration.
The sex, previous history of intracranial aneurysm/aSAH, older age score provides risk estimates for finding new intracranial aneurysms at 5, 10, and 15 years after initial screening, based on 3 easily retrievable predictors; this can help to define a personalized screening strategy after initial screening in people with a positive family history for aSAH.
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