[Mitochondrial respiratory chain complex Ⅱ deficiency and diseases]

This article reviews the structure and function of mitochondrial respiratory chain complex Ⅱ, and the clinical features, diagnosis, treatment and genetic analysis of mitochondrial respiratory chain complex Ⅱ deficiency. Mitochondrial complex Ⅱ, known as succinate dehydrogenase, is a part of the mitochondrial respiratory chain. It plays an important role in cellular oxidative phosphorylation. It is associated with oxidative stress and is a sensitive target for toxic substances and abnormal metabolin in cells. Clinical manifestations of respiratory chain complex Ⅱ deficiency are characterized by a wide variety of abnormalities. Progressive neuromuscular dysfunction is the most common syndrome. Cardiomyopathy, episodic vomit and hemolytic uremic syndrome are also encountered in a few cases. A precise diagnosis is dependent on enzyme activities assay of respiratory chain complexes and genetic analysis. Complex Ⅱ activities decreased in affected tissues. Pathogenic mutations in SDHA gene and SDHAF1 gene encoding assembly factor have been found so far. Clinical treatment aims at improving the mitochondrial function.