Patient-derived cells demonstrate that mutated RyR2 calcium leak underlies autism spectrum disorder and inherited arrhythmias

Abstract Catecholaminergic polymorphic ventricular tachycardia (CPVT) and autism spectrum disorder (ASD) are increasingly recognized as comorbid conditions, yet their shared molecular mechanisms remain unclear. This study investigates a novel RyR2-R169P mutation identified in a patient diagnosed with both CPVT and ASD, hypothesizing that this mutation drives calcium (Ca2+) dysregulation in cardiac and neuronal cells. Using patient-derived induced pluripotent stem cells, we generated ventricular-like cardiomyocytes and midbrain neurons. In cardiomyocytes, the RyR2-R169P mutation increased diastolic Ca2+ leak, elevated single-channel open probability, and induced arrhythmogenic Ca2+ waves under β-adrenergic stress. Similarly, neurons exhibited abnormal cytosolic Ca2+ levels, enlarged soma size, and a clear trend to disrupted neurotransmitter release, including reduced GABA and elevated L-DOPA and serotonin. RyR2 biochemical analysis showed reduced phosphorylation of RyR2 by CaMKII, increased PKA dependent phosphorylation and dissociation of calstabin2 in neurons. Pharmacological stabilization of RyR2 with S107 normalized Ca2+ handling in both cell types, restored neuronal morphology, and prevented calstabin2 depletion and CaMKII phosphorylation increase. S107 restores normal neurotransmitter release only when treatment starts before neuronal differentiation. Structural modeling revealed that the R169P mutation destabilizes the N-terminal domain of RyR2, priming the channel for pathological Ca2+ leak. These findings establish RyR2-R169P as a dual regulator of Ca2+ homeostasis, directly linking cardiac arrhythmogenesis to neurodevelopmental deficits. Our results highlight RyR2 dysfunction as a shared mechanism in CPVT-ASD comorbidity and propose Rycals as a promising therapeutic candidate for mitigating Ca2+-driven pathologies in both tissues. This work demonstrates the importance of RyR2 functional integrity in neurodevelopmental processes. One Sentence Summary Novel RyR2-R169P mutation causes calcium leak in hiPSC-derived cardiomyocytes and neurons, linking CPVT to autism via RyR2 dysfunction. Competing Interest Statement ARM is a board member and owns shares in RyCarma Therapeutics, which is targeting RyR channels for therapeutic purposes. All authors have nothing else to disclose. All authors read and approve the final version of the manuscript, and ensure it is the case. Funding Statement This work was supported by grants of INSERM, ANR Musage and Fenice and the Fondation Coeur et Recherche of the French Society of Cardiology. Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: This study was conducted in accordance with the Declaration of Helsinki and was approved by the Montpellier Hospital Review Board Committee (approval number 1003-HPS2). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Data Availability All data produced in the present study are available upon reasonable request to the authors.