Left Ventricular Noncompaction Cardiomyopathy (LVNC) is a very rare congenital heart disease. LVNC is a form of cardiomyopathy in which the fetal myocardium fails to "compact" during cardiac development and it may be associated with impairment of LV function and LV dilatation. Mutations in several sarcomere genes have been described in LVNC. Nexilin, encoded by NEXN, is a cardiac Z-disc protein that stabilizes the sarcomere. We evaluated nexilin as a disease gene for LVNC.