The Expanding Clinical and Genetic Spectrum of Muscle Glycogen Storage Disease 0, (GSD0B)

Glycogen storage disorders are a group of genetic disorders affecting glucose homeostasis in the body. Muscular glycogen stores are essential for liberating glucose for energy supply during bursts of activity and sustained muscle work. Muscle glycogen storage disease 0 (GSD0B) is associated with biallelic variants in GYS1 causing muscular glycogen synthetase deficiency and has previously been identified as a cause of sudden cardiac arrest in childhood. Muscle biopsies of affected living relatives demonstrated a paucity of glycogen staining. We describe 10 individuals from seven families to document the evolution of cardiac disease in individuals identified through cascade testing. This study expands knowledge of the clinical phenotype of muscular GSD type 0 to include adult survivors with myopathy and further describes the natural history of cardiac manifestations.