Desmoglein-2 Variants and N266S-Induced Pluripotent Stem Cells as a Model for Arrhythmogenic Cardiomyopathy: Genomic and Functional Insights

Desmoglein-2 (DSG2), the only desmosomal cadherin expressed in cardiomyocytes, is essential for cell adhesion and tissue integrity. DSG2 variants have been implicated in arrhythmogenic cardiomyopathy (ACM), but many remain of uncertain significance. The rare missense variant p.(N266S), among the first linked to biventricular ACM, still has unclear clinical relevance. We combined literature review, database analysis (GnomAD, ClinVar), and variant reclassification according to ACMG guidelines, validated in a retrospective Padua cohort. The p.(N266S) effect was assessed in cell models: HL-1 cardiomyocytes transfected with wild-type or mutant DSG2 and cardiomyocytes derived from induced pluripotent stem cells (iPSCs) from a healthy donor and a p.(N266S) carrier. Meta-analysis revealed many missense DSG2 variants of uncertain significance, with pathogenic substitutions clustering in calcium-binding extracellular domains and cytoplasmic plakophilin-2 interaction sites. In cellular models, p.(N266S) showed cytoplasmic mislocalization, desmosomal ultrastructural defects, dysregulation of collagen and ion channel genes, and asynchronous, fibrillation-like electrical activity. These findings support DSG2 as a key ACM determinant and indicate that p.(N266S) may disrupt desmosomal adhesion and electrophysiological stability, contributing to disease pathogenesis.