MYL4 and hypertrophic cardiomyopathy: Although it has been shown that the atrial light chain-1 (ALC1, protein coded by Myl4) is expressed in the atria, reexpression of ALC1 in the ventricle of patients with hypertrophic cardiomyopathy has been reported (Schaub et al., 1984) and improved contractility in ventricle reexpressing ALC1 is seen as an adaptive response during hypertrophy (Schaub et al., 1998).