Knowledge about the molecular basis of several diseases is steadily increasing; however our knowledge regarding the molecular basis of cardiomyopathies is still limited. Although the etiology of many inherited metabolic diseases accompanied by cardiomyopathy has been identified in the past decade, many of these entities are extremely rare, so that genetic studies are difficult to perform. Despite this, in some entities, the molecular and genetic basis of cardiomyopathy was identified. However, understanding of the molecular basis of cardiomyopathy is still in the beginning stages.