Mitochondrial complex I deficiency in a female with multiplex arthrogryposis congenita.

A 10-year-old female with arthrogryposis multiplex congenita is presented. Clinical, neurophysiologic, and histologic findings suggested a mild myopathy. The analysis of enzymatic activity in the homogenate and of mitochondrial function in saponin-permeabilized fibers from the muscle biopsy revealed an approximately twofold-decreased specific activity of the NADH:CoQ oxidoreductase (complex I of the mitochondrial respiratory chain) that was compensated for by an increased number of mitochondria. The complex I deficiency was also detected in cultivated skin fibroblasts of the patient. The observed defect of mitochondrial oxidative phosphorylation in arthrogryposis multiplex congenita may be of pathogenetic relevance.