Low Versus Standard Intensity Heparin Protocols in Adults Maintained on Extracorporeal Membrane Oxygenation: A Retrospective Cohort Study.

Background: Patients maintained on extracorporeal membrane oxygenation (ECMO) often require systemic anticoagulation to prevent circuit clotting and systemic thromboembolic complications. The optimal intensity of anticoagulation to balance the risk of bleeding and prevention of thrombotic complications in this patient population is not well described. Objective: To compare bleeding events in patients on ECMO anticoagulated with standard vs low intensity heparin protocols. Methods: This single-center, retrospective cohort study included adult patients on VA- or VV-ECMO and anticoagulated with low or standard intensity heparin protocols. The primary outcome was the incidence of major bleeding; secondary outcomes included the incidence of minor bleeding, thrombotic complications, heparin-induced thrombocytopenia, in-hospital mortality, time in therapeutic range, anti-Xa correlation with aPTT, intensive care unit and hospital lengths of stay, oxygenator exchanges, and rate of protocol switching. Results: A total of 27 patients (14 low intensity, 13 standard intensity) were included. There were six major bleeding events in the low intensity group and four in the standard intensity group (P = 0.69); there were four minor bleeding events in the low intensity group and five in the standard intensity group (P = 0.69). Seven patients in the standard intensity group switched protocols; zero patients in the low intensity group switched protocols (P = 0.002). There were no differences in any other outcomes. Conclusions: There was no difference in the incidence of any bleeding or thrombotic events when using a low vs standard intensity heparin protocol in patients on ECMO. A low intensity heparin strategy for patients on ECMO may be feasible and safe.

Prevalence of Perinatal Depression and Its Associated Risk Factors among Nepalese Women in Kathmandu, Nepal.

Perinatal mental health is a major public health issue that arises during pregnancy and/or after birth, with substantial implications for social, parental, and maternal functioning, as well as overall quality of life. The study aimed to determine the prevalence of perinatal depression and its associated risk factors among women who visited a maternity hospital in Kathmandu, Nepal. A cross-sectional study was conducted at the Paropakar Maternity and Women's Hospital in Kathmandu. A total of 300 women in their perinatal period were interviewed. The Edinburgh Perinatal Depression Scale (EPDS) was used to measure perinatal depression. The Poisson regression model was used to determine risk factors associated with perinatal depression. The mean age of respondents was 25.5 (SD 4.5) years; average age during their first pregnancy was 23.5 (SD 3.7) years; and 53.7% of respondents were in the antenatal period. The prevalence of depressive symptoms (EPDS ≥ 10) was 40% (95% CI 31.4% to 45.8%). Unsupportive family members (adjusted prevalence ratio [aPR] 2.23; 95% CI 1.75-2.86), postnatal period (aPR 2.64; 95% CI 1.97-3.53), complications faced during delivery (aPR 1.76; 95%CI 1.30-2.39), history of intimate partner violence (aPR 0.48; 95% CI 0.36-0.64), and first pregnancy at the age of ≤25 years (aPR 0.61; 95% CI 0.42-0.88) were identified as key risk factors of perinatal depression. Strong family support and the active involvement of partners in counselling can contribute to alleviating perinatal depression symptoms. Targeted interventions in health and well-being services should be implemented to address mental health burden during both pregnancy and postpartum periods.

Expert panel curation of 31 genes in relation to limb girdle muscular dystrophy.

OBJECTIVE: Limb girdle muscular dystrophies (LGMDs) are a group of genetically heterogeneous autosomal conditions with some degree of phenotypic homogeneity. LGMD is defined as having onset >2 years of age with progressive proximal weakness, elevated serum creatine kinase levels and dystrophic features on muscle biopsy. Advances in massively parallel sequencing have led to a surge in genes linked to LGMD. METHODS: The ClinGen Muscular Dystrophies and Myopathies gene curation expert panel (MDM GCEP, formerly Limb Girdle Muscular Dystrophy GCEP) convened to evaluate the strength of evidence supporting gene-disease relationships (GDR) using the ClinGen gene-disease clinical validity framework to evaluate 31 genes implicated in LGMD. RESULTS: The GDR was exclusively LGMD for 17 genes, whereas an additional 14 genes were related to a broader phenotype encompassing congenital weakness. Four genes (CAPN3, COL6A1, COL6A2, and COL6A3) were split into two separate disease entities, based on each displaying both dominant and recessive inheritance patterns, resulting in curation of 35 GDRs. Of these, 30 (86%) were classified as definitive, 4 (11%) as moderate, and 1 (3%) as limited. Two genes, POMGNT1 and DAG1, though definitively related to myopathy, currently have insufficient evidence to support a relationship specifically with LGMD. INTERPRETATION: The expert-reviewed assertions on the clinical validity of genes implicated in LGMDs form an invaluable resource for clinicians and molecular geneticists. We encourage the global neuromuscular community to publish case-level data that help clarify disputed or novel LGMD associations.

Reactivity of N terminal histidine of peptides towards excipients/impurity of excipients: A case study of liraglutide excipient compatibility study.

The selection of quality excipients is a crucial step in peptide formulation development. Apart from excipient incompatibility, process-related impurities or degradants of an excipient can interact with peptide-active pharmaceutical ingredients, forming the interaction products. The formaldehyde has been reported as an impurity of excipient in polyethylene glycol, glycerol, magnesium stearate, microcrystalline cellulose, mannitol, etc. The peptide contains various amino acids such as histidine, lysine, and arginine having free amine groups. These amine groups act as strong nucleophile and can increase the reactivity of peptides. PLGA is the most widely used biodegradable polymer in sustained-release formulations. The hydrolysis of PLGA generates glycolic acid and lactic acid impurities, which can form the interaction product with the amines of peptides. During the formulation development of Liraglutide, we have found few interaction products. The systematic characterization and mechanistic understanding of these interaction products lead us to imidazopyrimidine, glycolyl, and lactolyl moieties. These interaction products have been characterized thoroughly with the use of LC-HRMS, MS/MS, and hydrogen-deuterium exchange mass studies. The study revealed that the reactivity of N-terminal histidine must be considered for formulation development. Moreover, the quality of excipients with respect to presence of impurities must be considered as critical material attributes.

Protein-extending ACTN2 frameshift variants cause variable myopathy phenotypes by protein aggregation.

OBJECTIVE: The objective of the study is to characterize the pathomechanisms underlying actininopathies. Distal myopathies are a group of rare, inherited muscular disorders characterized by progressive loss of muscle fibers that begin in the distal parts of arms and legs. Recently, variants in a new disease gene, ACTN2, have been shown to cause distal myopathy. ACTN2, a gene previously only associated with cardiomyopathies, encodes alpha-actinin-2, a protein expressed in both cardiac and skeletal sarcomeres. The primary function of alpha-actinin-2 is to link actin and titin to the sarcomere Z-disk. New ACTN2 variants are continuously discovered; however, the clinical significance of many variants remains unknown. Thus, lack of clear genotype-phenotype correlations in ACTN2-related diseases, actininopathies, persists. METHODS: Functional characterization in C2C12 cell model of several ACTN2 variants is conducted, including frameshift and missense variants associated with dominant and recessive actininopathies. We assess the genotype-phenotype correlations of actininopathies using clinical data from several patients carrying these variants. RESULTS: The results show that the missense variants associated with a recessive form of actininopathy do not cause detectable alpha-actinin-2 aggregates in the cell model. Conversely, dominant frameshift variants causing a protein extension do form alpha-actinin-2 aggregates. INTERPRETATION: The results suggest that alpha-actinin-2 aggregation is the disease mechanism underlying some dominant actininopathies, and thus, we recommend that protein-extending frameshift variants in ACTN2 should be classified as pathogenic. However, this mechanism is likely elicited by only a limited number of variants. Alternative functional characterization methods should be explored to further investigate other molecular mechanisms underlying actininopathies.

A Retrospective Analysis of AngioVac Outcomes at a Tertiary Care Center.

Background: The AngioVac system is a vacuum aspiration device approved for removal of right-sided cardiac thrombi. It has also been used for management of right-sided endocarditis in selected cases. Retrospective case series have reported high success rate and acceptable 30-day mortality, but there is limited data regarding outcomes beyond the immediate postoperative period. The purpose of this study is to describe our institution's experience with the AngioVac system for thrombus, vegetation, and tumor removal with a significant improvement over previously reported 1-year survival rates. Methods: A retrospective review of AngioVac cases performed at our tertiary care center from 2016-2022 was done. From 2016-2022, 23 patients were identified, and their outcomes are described. Results: Our review demonstrates 81.8% procedural success, 100% procedure survival, 90.9% survival to discharge, and 81.8% 30-day survival rates. One-year survival rate was 72.7%. Complications including an 18.2% rate of new vasopressor use, 54.5% rate of transfusion requirement, and 4.5% rate of acute renal failure requiring hemodialysis were identified. Intraprocedural embolization occurred in 1 case requiring venoarterial extracorporeal membrane oxygenation support and thrombectomy. One case was converted to open surgical intervention. Conclusions: Our review further supports the safety and efficacy of minimally invasive vacuum-assisted aspiration systems beyond the immediate postoperative period in intracardiac thrombus, tumor, and right-sided infective endocarditis. Our institution's experience emphasizes a team-based approach including interventional cardiology and cardiothoracic surgery with a standardized imaging approach with transesophageal echocardiogram. Future guidelines are needed to include an algorithmic approach to intracardiac masses.

Drug delivery strategies for local immunomodulation in transplantation: Bridging the translational gap.

Drug delivery strategies for local immunomodulation hold tremendous promise compared to current clinical gold-standard systemic immunosuppression as they could improve the benefit to risk ratio of life-saving or life-enhancing transplants. Such strategies have facilitated prolonged graft survival in animal models at lower drug doses while minimizing off-target effects. Despite the promising outcomes in preclinical animal studies, progression of these strategies to clinical trials has faced challenges. A comprehensive understanding of the translational barriers is a critical first step towards clinical validation of effective immunomodulatory drug delivery protocols proven for safety and tolerability in pre-clinical animal models. This review overviews the current state-of-the-art in local immunomodulatory strategies for transplantation and outlines the key challenges hindering their clinical translation.

De novo variants in the RNU4-2 snRNA cause a frequent neurodevelopmental syndrome.

Around 60% of individuals with neurodevelopmental disorders (NDD) remain undiagnosed after comprehensive genetic testing, primarily of protein-coding genes1. Large genome-sequenced cohorts are improving our ability to discover new diagnoses in the non-coding genome. Here we identify the non-coding RNA RNU4-2 as a syndromic NDD gene. RNU4-2 encodes the U4 small nuclear RNA (snRNA), which is a critical component of the U4/U6.U5 tri-snRNP complex of the major spliceosome2. We identify an 18 base pair region of RNU4-2 mapping to two structural elements in the U4/U6 snRNA duplex (the T-loop and stem III) that is severely depleted of variation in the general population, but in which we identify heterozygous variants in 115 individuals with NDD. Most individuals (77.4%) have the same highly recurrent single base insertion (n.64_65insT). In 54 individuals in whom it could be determined, the de novo variants were all on the maternal allele. We demonstrate that RNU4-2 is highly expressed in the developing human brain, in contrast to RNU4-1 and other U4 homologues. Using RNA sequencing, we show how 5' splice-site use is systematically disrupted in individuals with RNU4-2 variants, consistent with the known role of this region during spliceosome activation. Finally, we estimate that variants in this 18 base pair region explain 0.4% of individuals with NDD. This work underscores the importance of non-coding genes in rare disorders and will provide a diagnosis to thousands of individuals with NDD worldwide.

Dominant stop-loss HNRNPA1 variants in juvenile-onset myopathy.

INTRODUCTION/AIMS: Heterogeneous nuclear ribonucleoprotein A1 is involved in nucleic acid homeostatic functions. The encoding gene HNRNPA1 has been associated with several neuromuscular disorders including an amyotrophic lateral sclerosis-like phenotype, distal hereditary motor neuropathy, multisystem proteinopathy, and various myopathies. We report two unrelated individuals with monoallelic stop loss variants affecting the same codon of HNRNPA1. METHODS: Two individuals with unsolved juvenile-onset myopathy were enrolled under approved institutional protocols. Phenotype data were collected and genetic analyses were performed, including whole-exome sequencing (WES). RESULTS: The two probands (MNOT002-01 and K1440-01) showed a similar onset of slowly progressive extremity and facial weakness in early adolescence. K1440-01 presented with facial weakness, winged scapula, elevated serum creatine kinase (CK) levels, and mild neck weakness. MNOT002-01 also exhibited elevated CK levels along with facial weakness, cardiomyopathy, respiratory dysfunction, pectus excavatum, a mildly rigid spine, and loss of ambulation. On quadriceps muscle biopsy, K1440-01 displayed rounded myofibers, mild variation in fiber diameter, and type 2 fiber hypertrophy, while MNOT002-01 displayed rimmed vacuoles. Monoallelic stop-loss variants in HNRNPA1 were identified for both probands: c.1119A>C p.*373Tyrext*6 (K1440-01) and c.1118A>C p.*373Serext*6 (MNOT002-01) affect the same codon and are both predicted to lead to the addition of six amino acids before termination at an alternative stop codon. DISCUSSION: Both stop-loss variants in our probands are likely pathogenic. Our findings contribute to the disease characterization of pathogenic variants in HNRNPA1. This gene should be screened in clinical diagnostic testing of unsolved cases of sporadic or dominant juvenile-onset myopathy.

The Rocker Technique for Atlantoaxial Dislocation With or Without Basilar Invagination: A Prospective Observational Study.

BACKGROUND AND OBJECTIVES: Atlantoaxial dislocation (AAD) poses a complex surgical challenge. Surgical approaches vary for reducible and irreducible cases. Challenges persist in reducing the atlantodental interval, especially in cases with oblique or vertical C1-C2 joints. The Rocker instrument (MJ Surgical), a less-explored technique, seeks to simplify instrumentation, reduce complexity, and enhance translation and retroflection reduction of AAD. METHODS: This prospective observational study was conducted from January 2022 to July 2023 at a tertiary neurosurgical center. Inclusion criteria covered all age groups with AAD, with or without basilar invagination. Exclusions included medically unstable patients and severe osteoporotic spine conditions. Preoperative assessments included dynamic X-rays, magnetic resonance imaging, and computed tomography scans. The Rocker technique was used, and patients were followed up for 6 to 12 months. RESULTS: Fifty-five patients (30 males, 25 females) underwent surgery. The mean age was 40.41 ± 15.01 years. Successful Rocker technique application was observed in 53 cases. Functional outcomes, assessed using Modified Ranawat grading, showed improvement postoperatively. Radiological outcomes revealed a significant reduction in the anterior atlantodental interval (7.21 ± 0.94 to 2.98 ± 0.78). Basilar invagination was reduced in all cases, whenever present. The technique exhibited versatility, applicability in various joint orientations, and cost-effectiveness. CONCLUSION: The Rocker technique is a safe and effective alternative for managing both reducible and irreducible AADs, with or without basilar invagination. It simplifies the reduction process, offering advantages over established techniques. Further trials, especially in rotational deformities, are warranted for validation.

Machine Learning Methods to Estimate Individualized Treatment Effects for Use in Health Technology Assessment.

BACKGROUND: Recent developments in causal inference and machine learning (ML) allow for the estimation of individualized treatment effects (ITEs), which reveal whether treatment effectiveness varies according to patients' observed covariates. ITEs can be used to stratify health policy decisions according to individual characteristics and potentially achieve greater population health. Little is known about the appropriateness of available ML methods for use in health technology assessment. METHODS: In this scoping review, we evaluate ML methods available for estimating ITEs, aiming to help practitioners assess their suitability in health technology assessment. We present a taxonomy of ML approaches, categorized by key challenges in health technology assessment using observational data, including handling time-varying confounding and time-to event data and quantifying uncertainty. RESULTS: We found a wide range of algorithms for simpler settings with baseline confounding and continuous or binary outcomes. Not many ML algorithms can handle time-varying or unobserved confounding, and at the time of writing, no ML algorithm was capable of estimating ITEs for time-to-event outcomes while accounting for time-varying confounding. Many of the ML algorithms that estimate ITEs in longitudinal settings do not formally quantify uncertainty around the point estimates. LIMITATIONS: This scoping review may not cover all relevant ML methods and algorithms as they are continuously evolving. CONCLUSIONS: Existing ML methods available for ITE estimation are limited in handling important challenges posed by observational data when used for cost-effectiveness analysis, such as time-to-event outcomes, time-varying and hidden confounding, or the need to estimate sampling uncertainty around the estimates. IMPLICATIONS: ML methods are promising but need further development before they can be used to estimate ITEs for health technology assessments. HIGHLIGHTS: Estimating individualized treatment effects (ITEs) using observational data and machine learning (ML) can support personalized treatment advice and help deliver more customized information on the effectiveness and cost-effectiveness of health technologies.ML methods for ITE estimation are mostly designed for handling confounding at baseline but not time-varying or unobserved confounding. The few models that account for time-varying confounding are designed for continuous or binary outcomes, not time-to-event outcomes.Not all ML methods for estimating ITEs can quantify the uncertainty of their predictions.Future work on developing ML that addresses the concerns summarized in this review is needed before these methods can be widely used in clinical and health technology assessment-like decision making.

Rapid Assessment of the Need for Evidence: Applying the Principles of Value of Information to Research Prioritisation.

We propose a short-cut heuristic approach to rapidly estimate value of information (VOI) using information commonly reported in a research funding application to make a case for the need for further evaluative research. We develop a "Rapid VOI" approach, which focuses on uncertainty in the primary outcome of clinical effectiveness and uses this to explore the health consequences of decision uncertainty. We develop a freely accessible online tool, Rapid Assessment of the Need for Evidence (RANE), to allow for the efficient computation of the value of research. As a case study, the method was applied to a proposal for research on shoulder pain rehabilitation. The analysis was included as part of a successful application for research funding to the UK National Institute for Health and Care Research. Our approach enables research funders and applicants to rapidly estimate the value of proposed research. Rapid VOI relies on information that is readily available and reported in research funding applications. Rapid VOI supports research prioritisation and commissioning decisions where there is insufficient time and resources available to develop and validate complex decision-analytic models. The method provides a practical means for implementing VOI in practice, thus providing a starting point for deliberation and contributing to the transparency and accountability of research prioritisation decisions.

Molecular cascade reveals sequential milestones underlying hippocampal neural stem cell development into an adult state.

Quiescent adult neural stem cells (NSCs) in the mammalian brain arise from proliferating NSCs during development. Beyond acquisition of quiescence, an adult NSC hallmark, little is known about the process, milestones, and mechanisms underlying the transition of developmental NSCs to an adult NSC state. Here, we performed targeted single-cell RNA-seq analysis to reveal the molecular cascade underlying NSC development in the early postnatal mouse dentate gyrus. We identified two sequential steps, first a transition to quiescence followed by further maturation, each of which involved distinct changes in metabolic gene expression. Direct metabolic analysis uncovered distinct milestones, including an autophagy burst before NSC quiescence acquisition and cellular reactive oxygen species level elevation along NSC maturation. Functionally, autophagy is important for the NSC transition to quiescence during early postnatal development. Together, our study reveals a multi-step process with defined milestones underlying establishment of the adult NSC pool in the mammalian brain.

Development of phenyl-urea-based small molecules that target penicillin-binding protein 4.

Staphylococcus aureus has the ability to invade cortical bone osteocyte lacuno-canalicular networks (OLCNs) and cause osteomyelitis. It was recently established that the cell wall transpeptidase, penicillin-binding protein 4 (PBP4), is crucial for this function, with pbp4 deletion strains unable to invade OLCNs and cause bone pathogenesis in a murine model of S. aureus osteomyelitis. Moreover, PBP4 has recently been found to modulate S. aureus resistance to ß-lactam antibiotics. As such, small molecule inhibitors of S. aureus PBP4 may represent dual functional antimicrobial agents that limit osteomyelitis and/or reverse antibiotic resistance. A high throughput screen recently revealed that the phenyl-urea 1 targets PBP4. Herein, we describe a structure-activity relationship (SAR) study on 1. Leveraging in silico docking and modeling, a set of analogs was synthesized and assessed for PBP4 inhibitory activities. Results revealed a preliminary SAR and identified lead compounds with enhanced binding to PBP4, more potent antibiotic resistance reversal, and diminished PBP4 cell wall transpeptidase activity in comparison to 1.

A World Update of Progress in Lower Extremity Transplantation: What's Hot and What's Not.

ABSTRACT: The field of vascularized composite allotransplantation (VCA) is the new frontier of solid organ transplantation (SOT). VCA spans life-enhancing/life-changing procedures such as upper extremity, craniofacial (including eye), laryngeal, tracheal, abdominal wall, penis, and lower extremity transplants. VCAs such as uterus transplants are life giving unlike any other SOT. Of all VCAs that have shown successful intermediate- to long-term graft survival with functional and immunologic outcomes, lower extremity VCAs have remained largely underexplored. Lower extremity transplantation (LET) can offer patients with improved function compared to the use of conventional prostheses, reducing concerns of phantom limb pain and stump complications, and offer an option for eligible amputees that either fail prosthetic rehabilitation or do not adapt to prosthetics. Nevertheless, these benefits must be carefully weighed against the risks of VCA, which are not trivial, including the adverse effects of lifelong immunosuppression, extremely challenging perioperative care, and delayed nerve regeneration. There have been 5 lower extremity transplants to date, ranging from unilateral or bilateral to quadrimembral, progressively increasing in risk that resulted in fatalities in 3 of the 5 cases, emphasizing the inherent risks. The advantages of LET over prosthetics must be carefully weighed, demanding rigorous candidate selection for optimal outcomes.

Stroke volume index (SVI) predicts all-cause mortality following transcatheter aortic valve replacement (TAVR).

BACKGROUND: Left ventricular systolic dysfunction in patients with severe aortic stenosis (AS) may result in low transvalvular gradients and underestimation of AS severity. A low-flow state may occur with reduced LVEF. Little is known about the implications of low compared to normal flow in patients with reduced LVEF undergoing transcatheter aortic valve replacement (TAVR). OBJECTIVES: We compared survival rates with degree of flow across stenosed aortic valves and left ventricular dysfunction. We hypothesized that the stroke volume index (SVI) offers essential information regarding survival following TAVR. METHODS: We retrospectively reviewed patients with LVEF <50 % undergoing TAVR at the Gates Vascular Institute in Buffalo, New York, from 2012 to 2017. We performed Receiver Operator Characteristics to examine the value of SVI in predicting the postoperative outcome of patients. Kaplan-Meier and Cox regression analyses were used to investigate the effect of a low-flow state on five-year survival in patients with systolic dysfunction undergoing TAVR. RESULTS: Five-year survival following TAVR was decreased in patients with low-flow AS (SVI <35 mL/m2) compared to patients with normal flow. Seventy-four percent (n = 50) of patients with low-flow compared to 43 % (n = 22) of patients with normal flow were deceased five years post-TAVR (p ≤0.001). ROC curve indicated SVI to be a clinical predictor of five year survival (AUC 0.732, 95 % CI: 0.641-0.823, p < 0.001). CONCLUSION: Patients with systolic dysfunction and low transvalvular flow AS had increased mortality five years following TAVR. These findings highlight a better prognosis in patients with normal flow and LV systolic dysfunction. CONDENSED ABSTRACT: Low-flow aortic stenosis can occur with reduced left ventricular function. We compared survival rates of patients with known reduced left ventricular function in low-flow and normal flow aortic stenosis. This retrospective single-center study examined mortality rates following transcatheter aortic valve replacement. The mean gradient was not a predictor of mortality. This study shows patients with low-flow aortic stenosis have decreased five-year survival following valve replacement.

Exercise-Induced QRS Prolongation in Brugada Syndrome: Implications for Improving Disease Phenotyping and Diagnosis.

BACKGROUND: Abnormal ventricular activation at rest is reported in Brugada syndrome (BrS). OBJECTIVES: The aim of this study was to evaluate the usefulness of dynamic changes in ventricular activation during exercise to improve disease phenotyping and diagnosis of BrS. METHODS: Digital 12-lead electrocardiograms during stress testing were analyzed retrospectively at baseline, peak exercise, and recovery in 53 patients with BrS and 52 controls. Biventricular activation was assessed from QRS duration (QRSd), whereas right ventricular activation was assessed from S wave duration in the lateral leads (I and V6) and terminal R wave duration in aVR. Exercise-induced changes in QRS parameters to predict a positive procainamide response were assessed in separate test and validation cohorts with suspected BrS. RESULTS: Baseline electrocardiogram parameters were similar between BrS and controls. QRSd shortened with exercise in all controls but prolonged in all BrS (-6.1 ± 6.0 ms vs 7.1 ± 6.5 ms [P < 0.001] in V6). QRSd in recovery was longer in BrS compared with controls (90 ± 12 ms vs 82 ± 11 ms in V6; P = 0.002). Both groups demonstrated exercise-induced S duration prolongation in V6, with greater prolongation in BrS (8.2 ± 14.3 ms vs 1.2 ± 12.4 ms; P < 0.001). Any exercise-induced QRSd prolongation in V6 differentiated those with a positive vs negative procainamide response with 100% sensitivity and 95% specificity in the test cohort, and 87% sensitivity and 93% specificity in the validation cohort. CONCLUSIONS: Exercise-induced QRSd prolongation is ubiquitous in BrS primarily owing to delayed right ventricular activation. This electrocardiogram phenotype predicts a positive procainamide response and may provide a noninvasive screening tool to aid in the diagnosis of BrS before drug challenge.

De novo TLK1 and MDM1 mutations in a patient with a neurodevelopmental disorder and immunodeficiency.

The Tousled-like kinases 1 and 2 (TLK1/TLK2) regulate DNA replication, repair and chromatin maintenance. TLK2 variants underlie the neurodevelopmental disorder (NDD) 'Intellectual Disability, Autosomal Dominant 57' (MRD57), characterized by intellectual disability and microcephaly. Several TLK1 variants have been reported in NDDs but their functional significance is unknown. A male patient presenting with ID, seizures, global developmental delay, hypothyroidism, and primary immunodeficiency was determined to have a heterozygous TLK1 variant (c.1435C>G, p.Q479E), as well as a mutation in MDM1 (c.1197dupT, p.K400∗). Cells expressing TLK1 p.Q479E exhibited reduced cytokine responses and elevated DNA damage, but not increased radiation sensitivity or DNA repair defects. The TLK1 p.Q479E variant impaired kinase activity but not proximal protein interactions. Our study provides the first functional characterization of NDD-associated TLK1 variants and suggests that, such as TLK2, TLK1 variants may impact development in multiple tissues and should be considered in the diagnosis of rare NDDs.