**Abstract**

Despite great advances in cardiovascular medicine, cardiomyopathies in children still are challenging for pediatricians as well as cardiologists. Pediatric cardiomyopathies can manifest in diverse phenotypes but are often life-threatening and have a poor prognosis. However, many therapeutic options available for adult patients do not apply for children, leaving a very limited portfolio to attenuate disease progression to avoid or postpone heart transplantation. Childhood cardiomyopathies can arise from different etiologies, but genetic defects such as mutations, for example, in sarcomeric proteins, which are pivotal for the contractile function, are common. This leads to the demand to identify new variants found by genetic screening as pathogenic and furthermore to allow a prognosis or risk assessment for related carriers, thus increasing the need to uncover molecular pathomechanisms of such mutations. This chapter aims to highlight the unique characteristics of pediatric cardiomyopathies in contrast to adult forms, including etiology, pathophysiology, genetics, as well as molecular mechanisms. We will also tackle currents options, challenges, and perspectives in diagnosis and treatment of pediatric cardiomyopathies.

**Keywords:** pediatric cardiomyopathy, mutations, sarcomere, molecular mechanism, genotype-phenotype correlation, calcium sensitivity, fibrosis, inflammation
