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Dryad

Patient-specific induced pluripotent stem cell properties implicate Ca2+-homeostasis in clinical arrhythmia associated with combined heterozygous RYR2 and SCN10A variants

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Feb 27, 2023 version files 167.90 MB

Abstract

We illustrate the use of induced pluripotent stem cells (iPSCs) as platforms for investigating cardiomyocyte phenotypes in a human family pedigree exemplified by novel heterozygous RYR2-A1855D and SCN10A-Q1362H variants occurring alone and in combination. The proband, a four-month-old boy, presented with polymorphic ventricular tachycardia (PVT). Genetic tests revealed double novel heterozygous RYR2-A1855D and SCN10A-Q1362H variants inherited from his father (F) and mother (M) respectively. His father showed ventricular premature beats (VPB); his mother was asymptomatic. Molecular biological characterisations demonstrated greater TNNT2 mRNA expression in the iPSCs-induced cardiomyocytes (iPS-CMs) than in the iPSCs. cTNTs became progressively organised, but cytoplasmic RYR2 and SCN10A aggregations occurred in the iPS-CMs. Proband-specific iPS-CMs showed decreased RYR2 and SCN10A mRNA expression. The RYR2-A1855D variant resulted in premature spontaneous sarcoplasmic reticular (SR) Ca2+ transients (PCTs), Ca2+ oscillations (COs), and increased action potential durations (APDs). SCN10A-Q1362H did not confer any specific phenotype. However, the combined heterozygous RYR2-A1855D and SCN10A-Q1362H variants in the proband iPS-CMs resulted in accentuated Ca2+ homeostasis disorders, AP prolongation and susceptibility to early afterdepolarisations (EADs) at high stimulus frequencies. These findings attribute the clinical phenotype in the proband to effects of the heterozygous RYR2 variant exacerbated by heterozygous SCN10A modification.