Test Details: Mitochondrial disease refers to a heterogeneous group of disorders resulting in defective cellular energy production due to abnormal oxidative phosphorylation (oxphos). Mitochondrial myopathy is a neuromuscular disorder, associated with three mutations in the mitochondrial tRNA encoding genes of Leu(A3302G), Ser(G7497A) and Glu(T14709C). The age of onset and the clinical course of diseases caused by mitochondrial mutations are highly variable. The heteroplasmy also underlies the phenotypic variability, characteristics of mitochondrial diseases. However symptomatic mitochondrial diseases generally reflect presence of 70-80% mutant mitochondria in the cells.