Mutations in the PRKAG2 gene encoding the 5′ Adenosine Monophosphate-Activated Protein Kinase (AMPK), specifically in its γ2 regulatory subunit, lead to Glycogen storage disease of heart, fetal congenital disorder (PRKAG2 syndrome). Here, PRKAG2 is linked to PRKAG2-related cardiomyopathy.