Defects of the respiratory chain

Abstract

Respiratory chain deficiencies have long been regarded as neuromuscular diseases only. However, oxidative phosphorylation (i.e. ATP synthesis by the respiratory chain) is not restricted to the neuromuscular system, but proceeds in all cells that contain mitochondria. Most nonneuromuscular organs and tissues are, therefore, also dependent upon mitochondrial energy supply. Owing to the twofold genetic origin of respiratory enzymes (nuclear DNA and mitochondrial [mtDNA]), a respiratory chain deficiency can theoretically give rise to any symptom in any organ or tissue at any age and with any mode of inheritance.