Ventricular noncompaction is a form of cardiomyopathy where increased 
trabeculation is present frequently affecting the left ventricle and resembling 
an embryonic state of heart development. Clinically, left ventricular 
noncompaction may manifest as congestive heart failure, arrhythmias, and/or 
thromboembolic events. There are multiple genes linked to noncompaction, but 
recently, sarcomere gene mutations were found in both familial and sporadic 
cases of noncompaction. The association of noncompaction with sarcomere 
mutations supports the classification of ventricular noncompaction as 
cardiomyopathy and raises interesting questions regarding the continuum of 
hypertrophic cardiomyopathy, dilated cardiomyopathy, and noncompaction. The 
mutational spectrum of sarcomere genes in these disorders highlights the 
importance of the MYH7 gene encoding beta-myosin heavy chain and ACTC1 encoding 
the cardiac actin gene. Intriguingly, these mutations also share a low but 
definitive incidence of congenital heart malformations including septal defects. 
These human genetic findings support that normal myocardial and sarcomere 
function are required for proper compaction and septation and that these 
mutations also portend a high risk of developing heart failure in later life.