Supplementary Material for: Right atrial myxoma in a young patient with a DSG-2 genetic mutation, a case report.

Introduction Primary heart tumors, particularly right atrial myxomas, are exceedingly rare. We present a particularly unique case of a young patient who was found to have a right atrial myxoma whilst carrying a desmoglein-2 (DSG-2) gene mutation, a mutation typically associated with cardiomyopathies but not previously reported concomitantly with atrial myxoma development. Case Presentation A young male in his twenties presented with constitutional symptoms, including dizziness and palpitations. An echocardiogram showed a 3.5–4 cm right atrial mass originating from the right atrium–superior vena cava junction. Surgical excision via midline sternotomy and right atriotomy was performed without complication. Histopathology confirmed a benign atrial myxoma. Given the patient's age and some clinical features suggestive of Carney Complex (CNC), genetic testing was undertaken. CNC associated mutations were excluded, but a DSG-2 mutation was identified. This gene is known to play a role in desmosomal integrity and has been implicated in arrhythmogenic right ventricular cardiomyopathy, hypertrophic cardiomyopathy, and dilated cardiomyopathy. However, it has not been previously associated with myxoma pathogenesis. Conclusion This is the first documented case of a right atrial myxoma concomitantly existing with a DSG-2 mutation. While the presence of this gene cannot be directly linked to the presence of a myxoma, the possibility of a genetic association is relevant. Further research and broader genetic screening in such cases can possibly uncover a potential link and aid in the further understanding of atypical cardiac tumour biology.