Phenotypic Expansion of GYG1-Related Disease Presenting as Hypertrophic Cardiomyopathy With Brugada Phenocopy.
Nurcan Arat, Umran Cetincelik, Zümrüt Arslan Gülten et al.
✦ AI-curated · Sources linked
Case in brief
A 31-year-old man presented with chest pain, fatigue, and exertional dyspnea. ECG showed a spontaneous type 1 Brugada pattern with complete right bundle branch block. Echocardiography found nonobstructive left ventricular hypertrophy with preserved ejection fraction, but markedly reduced, heterogeneous global longitudinal strain without apical sparing. Cardiac MRI showed mid-to-apical hypertrophy and patchy nonischemic late gadolinium enhancement consistent with fibrosis. Exome sequencing identified a homozygous pathogenic GYG1 variant, with functional and familial evidence supporting the diagnosis of GYG1-related glycogen storage disease type XV. Neurological examination, creatine kinase, and systemic evaluation were unremarkable; no pathogenic variants in established Brugada syndrome genes were detected.
What made this case unusual
The case combined cardiac-predominant GYG1-related disease, with hypertrophic cardiomyopathy and myocardial fibrosis, and a type 1 Brugada ECG pattern interpreted as a substrate-related phenocopy, despite no evident skeletal muscle or systemic involvement.
Diagnostic / clinical pearl
A Brugada-pattern ECG in a patient with myocardial hypertrophy and fibrosis may represent a phenocopy associated with structural disease; genetic evaluation can identify an underlying metabolic cardiomyopathy even when skeletal muscle findings are absent.