In these limited studies on human heart muscle samples we have found that a reduced level of phosphorylation of TnI and MyBP-C, the sarcomeric targets of PKA, is associated with pressure overload, i.e., a mean transvalvular pressure gradient >40 mmHg, but is not associated with hypertrophic cardiomyopathy in the absence of pressure overload. Here, MYBPC3 is linked to hypertrophic cardiomyopathy.