Mitochondrial disorder, clinical features, investigation, genetics and treatment. The aim of this article is to give an overview of mitochondrial disorders. As my younger brother got this disease early in his childhood I have got a special interest in this disease. The term mitochondrial myopathy refers to a group of neuromuscular disorders that all result in decrease of energy production in the body s tissues. Mitochondria, which are found in all cells in the body, are responsible for the generation of energy in the cells. When the mitochondria are not working properly, there is an energy shortage within the body and those organs that consume large amounts of energy such as muscle cells and neurons are often affected. The result is often muscle weakness, fatigue, and problems with the heart, eyes, and various other systems. Mitochondrial myopathies are typically caused by defects in a part of the mitochondria called the respiratory chain. The respiratory chain consists of four protein complexes known as type I, II, III and IV. If there is a deficiency in any of these complexes, the affected individual will have mitochondrial myopathy. Mitochondrial disorders are typically inherited disease. That is, they are passed from parent to child. They often inherited following by different types of inheritance patterns: Mandelian, Maternal, and Spontaneous mutation. Mitochondrial disease is difficult to diagnose. The investigations comprise metabolic screening, respiratory chain enzyme analysis in muscle tissue, muscle histology, and mutation analysis. The focus of this article is to learn more about: Clinical features, investigations, genetic mechanisms, diagnosis and treatment.