Myopathy with abnormal structure and function of muscle mitochondria.

When the rate of respiration of mitochrondria in the presence of inorganic phosphate cannot be increased by adding adenosine diphosphate (A.D.P.) but these particles can still couple respiration to phos- phorylation of A.D.P. to adenosine triphosphate (A.T.P.), the state of respiration is called 'loosely coupled'.The first patient in whom such a loosely coupled state of oxidative phosphorylation of the muscle mitochrondria was found was described by Ernster, Ikkos, and Luft (1959).The patient suffered from generalized myopathy with progressive asthenia and severe hypermetabolism.The structure of the muscle mitochondria was markedly altered as shown by electron microscopy (Luft, Ikkos, Palmieri, Ernster, and Afzelius, 1962).The second patient with the same biochemical disturbance of oxidative phosphorylation of the muscle mitochondria was described by Van Wijngaarden, Bethlem, Meijer, Hiilsmann, and Feltkamp (1967).This patient showed a proximal myopathy 'Temporary address: Dijkzigt Hospital, Rotterdam, the Netherlands.