Deletion of the Mtif3 gene in mice caused embryonic lethality whereas heart- and skeletal muscle-specific loss of MTIF3 causes mitochondrial dysfunction that leads to cardiomyopathy [2] or platelet-specific loss that causes thrombocytopenia and increased bleeding [66], indicating that mitochondrial protein synthesis is required in diverse tissue and cell types. The gene discussed is MTIF3; the disease is cardiomyopathy.