Functional analysis of rare variants found in schizophrenia implicates a critical role for GIT1-PAK3 signaling in neuroplasticity.

Although the pathogenesis of schizophrenia (SCZ) is proposed to involve alterations of neural circuits via synaptic dysfunction, the underlying molecular mechanisms remain poorly understood. Recent exome sequencing studies of SCZ have uncovered numerous single-nucleotide variants (SNVs); however, the majority of these SNVs have unknown functional consequences, leaving their disease relevance uncertain. Filling this knowledge gap requires systematic application of quantitative and scalable assays to assess known and novel biological functions of genes. Here we demonstrate loss-of-function effects of multiple rare coding SNVs found in SCZ subjects in the GIT1 (G protein-coupled receptor kinase interacting ArfGAP 1) gene using functional cell-based assays involving coexpression of GIT1 and PAK3 (p21 protein (Cdc42/Rac)-activated kinase 3). Most notably, a GIT1-R283W variant reported in four independent SCZ cases was defective in activating PAK3 as well as MAPK (mitogen-activated protein kinase). Similar functional deficits were found for a de novo SCZ variant GIT1-S601N. Additional assays revealed deficits in the capacity of GIT1-R283W to stimulate PAK phosphorylation in cultured hippocampal neurons. In addition, GIT1-R283W showed deficits in the induction of GAD1 (glutamate decarboxylase 1) protein expression. Extending these functional assays to 10 additional rare GIT1 variants revealed the existence of an allelic series with the majority of the SCZ case variants exhibiting loss of function toward MAPK activation in a manner correlated with loss of PAK3 activation. Taken together, we propose that rare variants in GIT1, along with other genetic and environmental factors, cause dysregulation of PAK3 leading to synaptic deficits in SCZ.

The utility of the MELD score in predicting mortality following liver resection for metastasis.

BACKGROUND: The MELD score has been demonstrated to be predictive of hepatectomy outcomes in mixed patient samples of primary and secondary liver cancers. Because MELD is a measure of hepatic dysfunction, prior conclusions may rely on the high prevalence of cirrhosis observed with primary lesions. This study aims to evaluate MELD score as a predictor of mortality and develop a risk prediction model for patients specifically undergoing hepatic metastasectomy. METHODS: ACS-NSQIP 2005-2013 was analyzed to select patients who had undergone liver resections for metastases. A receiver operating characteristic (ROC) analysis determined the MELD score most associated with 30-day mortality. A literature review identified variables that impact hepatectomy outcomes. Significant factors were included in a multivariable analysis (MVA). A risk calculator was derived from the final multivariable model. RESULTS: Among the 14,919 patients assessed, the mortality rate was 2.7%, and the median MELD was 7.3 (range = 34.4). A MELD of 7.24 was identified by ROC (sensitivity = 81%, specificity = 51%, c-statistic = 0.71). Of all patients above this threshold, 4.4% died at 30 days vs. 1.1% in the group ≤7.24. This faction represented 50.1% of the population but accounted for 80.3% of all deaths (p < 0.001). The MVA revealed mortality to be increased 2.6-times (OR = 2.55, 95%CI 1.69-3.84, p < 0.001). A risk calculator was successfully developed and validated. CONCLUSIONS: MELD>7.24 is an important predictor of death following hepatectomy for metastasis and may prompt a detailed assessment with the provided risk calculator. Attention to MELD in the preoperative setting will improve treatment planning and patient education prior to oncologic liver resection.

Analysis of exome sequence in 604 trios for recessive genotypes in schizophrenia.

Genetic associations involving both rare and common alleles have been reported for schizophrenia but there have been no systematic scans for rare recessive genotypes using fully phased trio data. Here, we use exome sequencing in 604 schizophrenia proband-parent trios to investigate the role of recessive (homozygous or compound heterozygous) nonsynonymous genotypes in the disorder. The burden of recessive genotypes was not significantly increased in probands at either a genome-wide level or in any individual gene after adjustment for multiple testing. At a system level, probands had an excess of nonsynonymous compound heterozygous genotypes (minor allele frequency, MAF ⩽ 1%) in voltage-gated sodium channels (VGSCs; eight in probands and none in parents, P = 1.5 × 10(-)(4)). Previous findings of multiple de novo loss-of-function mutations in this gene family, particularly SCN2A, in autism and intellectual disability provide biological and genetic plausibility for this finding. Pointing further to the involvement of VGSCs in schizophrenia, we found that these genes were enriched for nonsynonymous mutations (MAF ⩽ 0.1%) in cases genotyped using an exome array, (5585 schizophrenia cases and 8103 controls), and that in the trios data, synaptic proteins interacting with VGSCs were also enriched for both compound heterozygosity (P = 0.018) and de novo mutations (P = 0.04). However, we were unable to replicate the specific association with compound heterozygosity at VGSCs in an independent sample of Taiwanese schizophrenia trios (N = 614). We conclude that recessive genotypes do not appear to make a substantial contribution to schizophrenia at a genome-wide level. Although multiple lines of evidence, including several from this study, suggest that rare mutations in VGSCs contribute to the disorder, in the absence of replication of the original findings regarding compound heterozygosity, this conclusion requires evaluation in a larger sample of trios.

Copy number variation in schizophrenia in Sweden.

Schizophrenia (SCZ) is a highly heritable neuropsychiatric disorder of complex genetic etiology. Previous genome-wide surveys have revealed a greater burden of large, rare copy number variations (CNVs) in SCZ cases and identified multiple rare recurrent CNVs that increase risk of SCZ although with incomplete penetrance and pleiotropic effects. Identification of additional recurrent CNVs and biological pathways enriched for SCZ CNVs requires greater sample sizes. We conducted a genome-wide survey for CNVs associated with SCZ using a Swedish national sample (4719 cases and 5917 controls). High-confidence CNV calls were generated using genotyping array intensity data, and their effect on risk of SCZ was measured. Our data confirm increased burden of large, rare CNVs in SCZ cases as well as significant associations for recurrent 16p11.2 duplications, 22q11.2 deletions and 3q29 deletions. We report a novel association for 17q12 duplications (odds ratio=4.16, P=0.018), previously associated with autism and mental retardation but not SCZ. Intriguingly, gene set association analyses implicate biological pathways previously associated with SCZ through common variation and exome sequencing (calcium channel signaling and binding partners of the fragile X mental retardation protein). We found significantly increased burden of the largest CNVs (>500 kb) in genes present in the postsynaptic density, in genomic regions implicated via SCZ genome-wide association studies and in gene products localized to mitochondria and cytoplasm. Our findings suggest that multiple lines of genomic inquiry--genome-wide screens for CNVs, common variation and exonic variation--are converging on similar sets of pathways and/or genes.

Detecting large copy number variants using exome genotyping arrays in a large Swedish schizophrenia sample.

Although copy number variants (CNVs) are important in genomic medicine, CNVs have not been systematically assessed for many complex traits. Several large rare CNVs increase risk for schizophrenia (SCZ) and autism and often demonstrate pleiotropic effects; however, their frequencies in the general population and other complex traits are unknown. Genotyping large numbers of samples is essential for progress. Large cohorts from many different diseases are being genotyped using exome-focused arrays designed to detect uncommon or rare protein-altering sequence variation. Although these arrays were not designed for CNV detection, the hybridization intensity data generated in each experiment could, in principle, be used for gene-focused CNV analysis. Our goal was to evaluate the extent to which CNVs can be detected using data from one particular exome array (the Illumina Human Exome Bead Chip). We genotyped 9100 Swedish subjects (3962 cases with SCZ and 5138 controls) using both standard genome-wide association study (GWAS) and exome arrays. In comparison with CNVs detected using GWAS arrays, we observed high sensitivity and specificity for detecting genic CNVs 400 kb including known pathogenic CNVs along with replicating the literature finding that cases with SCZ had greater enrichment for genic CNVs. Our data confirm the association of SCZ with 16p11.2 duplications and 22q11.2 deletions, and suggest a novel association with deletions at 11q12.2. Our results suggest the utility of exome-focused arrays in surveying large genic CNVs in very large samples; and thereby open the door for new opportunities such as conducting well-powered CNV assessment and comparisons between different diseases. The use of a single platform also minimizes potential confounding factors that could impact accurate detection.

[Implantable cardiac defibrillator (ICD): basics and present clinical guidelines]. / Défibrillateur automatique implantable (DAI): principes de base et indications cliniques actuelles.

An implantable cardiac defibrillator (ICD) is a cardiac implantable electronic device that is capable of identifying and treating ventricular arrhythmias. Consideration about the type of ICD to select for a given patient include whether the patient has bradycardia requiring pacing support, has associated atrial tachyarrhythmias, or would benefit from cardiac resynchronization therapy. The ICD functions by continuously monitoring the patient's cardiac rate and delivering therapies (anti-tachycardia pacing, shocks) when the rate exceeds the programmed rate "cutoff". Secondary prevention trials have demonstrated that ICDs reduce the incidence of arrhythmic death and total mortality in patients presenting with a cardiac arrest. ICDs are also indicated for primary prevention of sudden cardiac death in specific high-risk subgroups of patients.

[Percutaneous closure of left atrial appendage: a new hope for patients with atrial fibrillation?]. / Fermeture percutanée de l'auricule gauche: un nouvel espoir pour le patient en fibrillation auriculaire?

Atrial fibrillation (AF) is the most common cardiac arrhythmia. The risk of thromboembolic events is important, and at that time, there is no definite treatment for AF. Oral anticoagulation also represents a hemorrhagic risk factor. Ninety percent of atrial thrombi are located within the left atrial appendage. The percutaneous closure of this left atrial appendage with a device has been shown to decrease thromboembolic events even after interruption of oral anticoagulation as compared to warfarin in a recent randomized study. Recent data support this innovative technique as a reasonable alternative to long term anticoagulation in patients at high risk of bleeding.

Predictive models of syncope causes in an outpatient clinic.

UNLABELLED: The investigation of unexplained syncope remains a challenging clinical problem. In the present study we sought to evaluate the diagnostic value of a standardized work-up focusing on non invasive tests in patients with unexplained syncope referred to a syncope clinic, and whether certain combinations of clinical parameters are characteristic of rhythmic and reflex causes of syncope. METHODS AND RESULTS: 317 consecutive patients underwent a standardized work-up including a 12-lead ECG, physical examination, detailed history with screening for syncope-related symptoms using a structured questionnaire followed by carotid sinus massage (CSM), and head-up tilt test. Invasive testings including an electrophysiological study and implantation of a loop recorder were only performed in those with structural heart disease or traumatic syncope. Our work-up identified an etiology in 81% of the patients. Importantly, three quarters of the causes were established non invasively combining head-up tilt test, CSM and hyperventilation testing. Invasive tests yielded an additional 7% of diagnoses. Logistic analysis identified age and number of significant prodromes as the only predictive factors of rhythmic syncope. The same two factors, in addition to the duration of the ECG P-wave, were also predictive of vasovagal and psychogenic syncope. These factors, optimally combined in predictive models, showed a high negative and a modest positive predictive value. CONCLUSION: A standardized work-up focusing on non invasive tests allows to establish more than three quarters of syncope causes. Predictive models based on simple clinical parameters may help to distinguish between rhythmic and other causes of syncope.

[Past, present and future of percutaneous catheter ablation technologies for cardiac arrhythmias]. / Passé, present et futur des technologies d'ablation percutanée des arythmies cardiaques.

Drug therapy treatment of cardiac arrhythmias has been disappointing, while percutaneous catheter ablation, efficient and at low risk, has become the first line therapy of the majority of rhythm disturbances, in only two decades. The ultimate challenge, which is atrial fibrillation ablation, is on the way to be successfully solved. This is mainly due to: innovative ablational energy sources; 3D virtual electro-anatomical reconstructions of heart cavities, to map and understand complex arrhythmias' circuits; revolutionary magnetic navigation systems that permit the target positioning of the catheters in the most inaccessible places, even though the operator works at a command board placed away from the patient.

[What do we actually know about out-of-hospital cardiac arrest?]. / Arrêt cardiaque extrahospitalier: la situation actuelle.

Each year at least 300,000 people in the United States and 8000 to 10,000 people in Switzerland suffer from out-of-hospital cardiac arrest, mostly due to ventricular fibrillation. Early defibrillation provides definitive treatment for most of cardiac arrest victims. Semi-automatic external defibrillators are easy to handle devices allowing to deliver an early electric shock and can be successfully used by lay people following minimal training. Newer strategies of defibrillation designed to respond faster to out-of-hospital cardiac arrest, including public access defibrillation, as well as improvement of each link of the chain of survival appears as the best strategy for the management of out-of-hospital cardiac arrest.

Morphological, clinical and genetic aspects in a family with a novel LAMP-2 gene mutation (Danon disease).

A family with several cases of severe cardiomyopathy and moderate myopathy is described, affecting two brothers and their cousin as well as their mothers. One boy died of sudden cardiac arrest at 17 years of age. The two brothers were treated with an implantable defibrillator and their mother died suddenly at 40 years of age. Muscle biopsy in males showed vacuolar myopathy in two cases, and no abnormality on standard staining in the third case. Cardiac biopsies showed hypertrophic and vacuolated fibres. Complete absence of LAMP-2 was demonstrated by immunohistochemistry on the vacuolated skeletal and cardiac muscle, but also on the morphologically normal skeletal muscle. Sequencing of LAMP-2 gene showed a novel S157X mutation in exon 4. Danon disease is a rare and potentially lethal cause of hypertrophic cardiomyopathy. Diagnosis can be made by immunohistochemistry performed on cardiac or muscle biopsy, and confirmed by genetic analysis, which also allows for easy family screening and counselling.

[Implantable defibrillator. Update]. / Le défibrillateur implantable. Mise au point.

The implantable cardioverter-defibrillator is a device able to detect and efficiently treat life-threatening ventricular arrhythmias. Its decisive accomplishment in reducing sudden cardiac death and total cardiac mortality, opposed to the insufficient reliability of the traditional therapies explains its present ascendancy. In this review, the working principles and the implant techniques are developed, as well as the complications and the usual problems which could be encountered in implanted patients. Finally, the current indications are discussed in the light of recent clinical trials.

Late clinical outcome after successful radiofrequency catheter ablation of accessory pathways.

AIMS: To evaluate the long-term clinical results of patients who underwent successful radiofrequency catheter ablation of a symptomatic drug-resistant accessory-pathway-mediated tachycardia. METHODS AND RESULTS: Clinical follow-up was done by direct contact with the patients and their physicians. One hundred and eighty consecutive patients (113 males, 67 females) were followed during a median period of 48.1 months. There were seven procedure related complications (4%). During the follow-up period, 79% of the patients remained asymptomatic; 14% complained of short bouts of palpitations due to isolated or short runs of atrial or ventricular premature beats; 7% had sustained palpitations due either to accessory pathway recurrence (4%) or supraventricular tachyarrhythmias not associated with an accessory pathway (3%). Symptoms due to accessory pathway recurrence appeared either in the first month following the ablation or at least later than 3 months when sustained supraventricular arrhythmias occurred related to another cause. CONCLUSIONS: Initially successful radiofrequency catheter ablation has a low, long-term recurrence rate (4%). Recurrence of accessory-pathway-mediated tachycardia is observed during the first month while later symptoms suggest supraventricular arrhythmias from another cause.

[New perspectives on the surgical treatment of atrial fibrillation. From extracorporeal circulation surgery to minimally invasive heart surgery]. / Nouvelles perspectives dans le traitement chirurgical de la fibrillation auriculaire. De la chirurgie sous circulation extra-corporelle à la chirurgie minimale invasive à coeur battant.

Atrial fibrillation remains the most common sustained tachyarrhythmia, with recurrent symptoms and thromboembolic risks. In the last few years it has become the recent focus of intense clinical and experimental interest which confirm that this arrhythmia is due to atrial re-entry mechanisms. With better understanding of its physiopathology, an efficient surgical treatment has been developed. Surgical interventions of supraventricular tachycardias is targeted to neutralize the arrhythmogenic disorder using exclusion or ablation. Several methods can be used like surgical incisions, cryoablation, radiofrequency ablation or laser energy. Surgery being a transparietal approach requiring cardiopulmonary bypass, atriotomy and myocardial preservation, associated morbidity is due to the high technicalities of this treatment and not necessarily the therapy itself. New developments in the surgical approach tend to avoid cardiopulmonary bypass to reduce morbidity. The aim of this review is to describe and report our own experiences in this evolving domain of atrial fibrillation surgery.

Evidence rather than costs must guide use of the implantable cardioverter defibrillator.

Randomized controlled trials have shown superior survival rates with implantable cardioverter defibrillators (ICDs) compared with antiarrhythmic drugs in survivors of cardiac arrest and life-threatening ventricular tachyarrhythmias, as well as in high-risk patients with ischemic heart disease and inducible ventricular tachycardia (VT). Current defibrillators are small and implanted with techniques similar to standard pacemakers. They provide high-energy shocks for ventricular fibrillation (VF) and rapid VT, antitachycardia pacing for monomorphic VT, and antibradycardia pacing. Limited evidence suggests that ICD therapy is cost-effective when compared with other widely accepted treatments. The use of ICDs is likely to continue to expand in the future. Ongoing clinical trials will define further prophylactic indications of the ICD and clarify its cost-effectiveness ratio in different clinical settings.

Heart rate dynamics at the onset of ventricular tachyarrhythmias as retrieved from implantable cardioverter-defibrillators in patients with coronary artery disease.

BACKGROUND: The recent availability of implantable cardioverter-defibrillators (ICDs) that record 1024 R-R intervals preceding a ventricular tachyarrhythmia (VTA) provides a unique opportunity to analyze heart rate variability (HRV) before the onset of VTA. METHODS AND RESULTS: Fifty-eight post-myocardial infarction patients with an implanted ICD for recurrent VTA provided 2 sets of 98 heart rate recordings in sinus rhythm: (1) before a VTA and (2) during control conditions. Three subgroups were considered according to the antiarrhythmic (AA) drug regimen. A state of sympathoexcitation was suggested by the significant reduction in HRV before VTA onset compared with control conditions. beta-Blockers and dl-sotalol enhanced HRV in control recordings; nevertheless, HRV declined before VTA independent of AA drugs. A gradual increase in heart rate and decrease in sinus arrhythmia at VTA onset were specific findings of patients who received dl-sotalol. CONCLUSIONS: The peculiar heart rate dynamics observed before VTA onset are suggestive of a state of sympathoexcitation that is independent of AA drugs.

[Cardiac pacing. Percutaneous extraction of infected pacing catheter]. / Stimulation cardiaque. Extraction percutanée de sondes infectées.

Infection of a cardiac pacemaker is a rare but serious complication. Percutaneous ablation of the pacemaker and pacing catheter is the only effective treatment. Techniques of extraction of pacing systems have been evaluated but the long term results require analysis. Eighteen patients with infection of cardiac pacemakers underwent extraction of one or more pacing catheters (14 atrial and 20 ventricular) in one same centre. The indication was infection of the pacemaker unit (12 cases) or septicaemia (6 cases) The causal organism was a staphylococcus (aureus: 7 cases, epidermidis: 10 cases, capitis: 1 case). Three techniques were used: 1) direct external manual traction, 2) internal traction with several devices, 3) endovascular counter-traction (Byrd-Cook system). The time from primary implantation of the pacing catheter to its extraction was 42 months and from last pacemaker manipulation to infection, 23 months. The average duration of the extraction procedure was 120 +/- 45 minutes; that of fluoroscopy was 10 +/- 6 minutes. The first technique was used 12 times, the second 8 times and the third 14 times, with complete extraction of the catheter in 88.2% of cases. The metallic tip of the distal electrode embolised in 2 cases and remained stuck in the right ventricle in 1 case. Only one pacing catheter was abandoned. After an average follow-up of 45 months, none of the patients had recurrent infection or any other complication. The authors conclude that extraction of infected pacing catheters is safe and effective. It is the treatment of choice of this complication.

Vg1 RBP intracellular distribution and evolutionarily conserved expression at multiple stages during development.

We have analyzed the expression and intracellular distribution, during oogenesis and embryogenesis, of Vg1 RBP, a protein implicated in the intracellular localization of Vg1 mRNA to the vegetal cortex of Xenopus oocytes. Vg1 RBP (protein) colocalizes with Vg1 RNA at all stages of oogenesis. Vg1 RBP RNA, however, localizes to the animal pole during late oogenesis, and remains in the animal blastomeres and ectodermal precursors until its zygotic transcription is activated, around stage 12. Vg1 RBP mRNA then becomes expressed throughout the neural epithelium. Vg1 RBP mRNA expression is also detected in what appears to be neural crest cells undergoing delamination and lateral migration. By tailbud stages, Vg1 RBP expression is present in the branchial arches, otic vesicle, pronephros, and along the neural tube. To examine the expression pattern in different species, we cloned the zebrafish homolog of Vg1 RBP by using a highly homologous EST clone to screen an embryonic cDNA library. In situ hybridization reveals that Vg1 RBP RNA localizes early in oogenesis to the animal pole. Although Vg1 RBP RNA is detected in all blastomeres of the early embryo, the expression pattern in the one day old zebrafish embryo is almost identical to that of the equivalent stage Xenopus embryo. These results indicate that the zygotic expression pattern is similar in frogs and fish, and that there is a conserved zygotic expression of Vg1 RBP distinct from its expression in the oocyte.