PRKAG2 and cardiomyopathy: A previous study by Arad et al. suggested that Danon disease is distinguishable from cardiomyopathy due to PRKAG2 or sarcomere‐protein defects by male sex, early onset of symptoms, massive concentric LVH, asymptomatic elevations of serum‐chemistry values, and electrocardiographic abnormalities, particularly ventricular preexcitation (Arad et al., 2005).