We also discuss heart diseases in which titin plays a role, such as dilated cardiomyopathy (DCM), heart failure with preserved ejection fraction (HFpEF), and diabetic cardiomyopathy (DbCM) (Herman et al., 2012; Zile et al., 2015; Hopf et al., 2018). The gene discussed is TTN; the disease is familial dilated cardiomyopathy.