Nemaline cardiomyopathy in a young adult: An ultraimmunohistochemical study and review of the literature

Heart transplantation was performed in a 26-year-old man who suffered from severe dilatative cardiomyopathy. A nemaline myopathy characterized by the accumulation of Z-line material and the formation of rod-like structures ha d been diagnosed in the skeletal muscle. Routine light microscopy of the he art disclosed only nonspecific findings. On electron microscopy scattered c ardiomyocytes showed formations of rod-like structures and a structural des integration of contractile filaments near the intercalated disks, Immunocyt ochemistry at the light and electron microscopical level exhibited an accum ulation of alpha -actinin, desmin, and occasionally vinculin in abnormal ca rdiomyocytes. The rods were specifically stained with alpha -actinin and we re less immunoreactive for desmin. No mutations were revealed in the skelet al muscle alpha -actin gene. The results illustrate a complex derangement o f the cytoskeletal apparatus in nemaline cardiomyopathy. Nemaline cardiomyo pathy may be difficult to diagnose in routine diagnostic procedures. A clos e correlation between the severity of cardiac dysfunction and the morpholog ical expression of the disease in the heart may not be found. Nemaline card iomyopathy should be included in the differential diagnosis of dilatative c ardiomyopathy and may be diagnosed with certainty by ultrastructural-immunh istochemical investigations.