Generation of human induced pluripotent stem cell (hiPSC) lines from patients with extreme high and low polygenic scores for QT interval.

Long QT syndrome (LQTS), an inherited cardiac arrhythmia syndrome with congenital and drug-induced presentations and known monogenic and polygenic contributions, represents a significant clinical challenge due to its complex genetic underpinning and propensity for fatal arrhythmias. In this study, we generated induced pluripotent stem cells (iPSCs) reprogrammed from peripheral blood mononuclear cells (PBMCs) of six patients with extreme polygenic scores for short and long corrected QT intervals. This patient-specific approach will enable us to better understand variable expressivity and penetrance of LQTS, using rigorously validated iPSC lines serve as a vital resource for elucidating the molecular mechanisms underlying LQTS.

EFP Analyzer: A fast, accurate, and easy-to-teach program for analyzing Extracellular Field Potentials from iPSC-derived cardiomyocytes.

Rationale: Induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) are an emerging model for determining drug effects and modeling disease. Specialized devices can generate Extracellular Field Potential (EFP) measurements from these cells, analogous to the ventricular complex of the electrocardiogram.

Objective: The objective of this study was to develop an easy-to-use, easy-to-teach, reproducible software tool to measure EFPs.

Multiplexed Assays of Variant Effect and Automated Patch Clamping Improve -LQTS Variant Classification and Cardiac Event Risk Stratification.

Background: Long QT syndrome is a lethal arrhythmia syndrome, frequently caused by rare loss-of-function variants in the potassium channel encoded by . Variant classification is difficult, often because of lack of functional data. Moreover, variant-based risk stratification is also complicated by heterogenous clinical data and incomplete penetrance.

Multiplexed Assays of Variant Effect and Automated Patch-clamping Improve -LQTS Variant Classification and Cardiac Event Risk Stratification.

Background: Long QT syndrome (LQTS) is a lethal arrhythmia syndrome, frequently caused by rare loss-of-function variants in the potassium channel encoded by . Variant classification is difficult, often owing to lack of functional data. Moreover, variant-based risk stratification is also complicated by heterogenous clinical data and incomplete penetrance.

Multicenter clinical and functional evidence reclassifies a recurrent noncanonical filamin C splice-altering variant.

Background: Truncating variants in filamin C (FLNC) can cause arrhythmogenic cardiomyopathy (ACM) through haploinsufficiency. Noncanonical splice-altering variants may contribute to this phenotype.

Objective: The purpose of this study was to investigate the clinical and functional consequences of a recurrent FLNC intronic variant of uncertain significance (VUS), c.

A massively parallel assay accurately discriminates between functionally normal and abnormal variants in a hotspot domain of KCNH2.

Many genes, including KCNH2, contain "hotspot" domains associated with a high density of variants associated with disease. This has led to the suggestion that variant location can be used as evidence supporting classification of clinical variants. However, it is not known what proportion of all potential variants in hotspot domains cause loss of function.

High-throughput discovery of trafficking-deficient variants in the cardiac potassium channel K11.1.

Background: KCHN2 encodes the K11.1 potassium channel responsible for I, a major repolarization current during the cardiomyocyte action potential. Variants in KCNH2 that lead to decreased I have been associated with long QT syndrome type 2 (LQT2).