ACTC1 and Glycogen storage disease due to glycogenin deficiency: Due to the genetic heterogeneity of HCM, a comprehensive panel should be used for screening that covers not only the main sarcomeric culprits (e.g., TNNT2, MYH7, MYBPC3, TNNI3, ACTC), but also other causes including RASopathies, mitochondrial proteins, and glycogen storage diseases (29).