**2. Mitochondria**

Mitochondria are genetically controlled by both nuclear DNA and the mitochondrial genome [1, 4]. A wide range of molecular defects have been identified in the human mitochondrial genome [4–9]. Diseases due to mutations in the mitochondrial genome are clinically, genetically, and biochemically diverse [1, 2, 4, 6, 10]. Similarly, deficiencies in mitochondrial genes encoded by nuclear genome can also lead various mitochondrial disorders and a wide range of cellular perturbations such as undue reactive oxygen species and distracted apoptosis, aberrant calcium homeostasis, and deficient energy production. This in turn leads failure to meet the requirements of numerous organs, especially those with high energy needs. Hence, various pathological conditions appears due to impaired mitochondrial function in human body involving different cell types, tissues, and organs including heart and brain. Such multiorgan manifestations are all mitochondria related and these diseases varies from epilepsy to cardiac myopathies.
