In brief, various studies provide evidence that altered protein kinase activity and phosphorylation states of myosin-binding protein and or myosin light chain 2 directly determine myosin head proximity to actin filaments and thereby cardiomyocyte and ventricular relaxation rates in prediabetes, hypertrophic cardiomyopathy, and heart failure (Colson et al., 2008; Tong et al., 2008; Waddingham et al., 2019). This evidence concerns the gene MYL2 and hypertrophic cardiomyopathy.