89 R. Rajendram et al. (eds.), Branched Chain Amino Acids in Clinical Nutrition: Volume 2, Nutrition and Health, DOI 10.1007/978-1-4939-1914-7_7, © Springer Science+Business Media New York 2015 Key Points • Cardiomyopathies are diseases of the myocardium that can be complicated by heart failure, arrhythmias, and sudden death. • Mitochondrial cardiomyopathies are a subgroup of cardiomyopathies produced by defects in the energetic metabolism. • Cardiac involvement is reported in 20–25 % of patients with mitochondrial disorders. • Mitochondrial cardiomyopathies can result from mutations in either nuclear or mitochondrial encoded genes. • Mitochondrial tRNA Leu , tRNA Ile , and tRNA Val are mutational hotspots for mitochondrial cardiomyopathies. • Most patients with mutations in the mitochondrial tRNA Val gene ( MT- TV) present with a hypertro- phic cardiomyopathy. • The MT- TV gene should be included in the molecular diagnosis of patients when there is a high suspicion of mitochondrial cardiomyopathy. Abbreviations ARVC Arrhythmogenic right ventricular cardiomyopathy CM Cardiomyopathy CPEO Chronic progressive external ophthalmoplegia DCM Dilated cardiomyopathy HCM Hypertrophic cardiomyopathy MCM Mitochondrial cardiomyopathy Chapter 7 Mitochondrial tRNA Valine in Cardiomyopathies M. Esther Gallardo, Teresa Galera, Rafael Garesse, and Belén Bornstein M.E. Gallardo, M.S., Ph.D. (*) • T. Galera, B.S. • R. Garesse, Ph.D. • B. Bornstein, Ph.D. Departamento de Bioquímica, Facultad de Medicina, Instituto de Investigaciones Biomédicas “Alberto Sols” UAM-CSIC, Universidad Autónoma de Madrid, Madrid, Spain e-mail: egallardo@iib.uam.es Keywords Mitochondrial disease • Mitochondrial DNA • Cardiomyopathy • Mitochondrial cardio- myopathy • MT- TV • MT- TL1 • MT- TI