[Respiratory chain diseases in infancy. Clinical presentation and diagnosis].

Nineteen children with defects of the mitochondrial respiratory chain are described. First symptoms appeared during the first two years of their lives. Four types of clinical pictures were identified: 1/neonatal hypotonia. 2/cardiomyopathy. 3/progressive neurological deterioration. 4/multisystem disease. A study of pyruvate and fatty acids metabolism and a skeletal muscle biopsy were performed in all cases. Elevation of beta-hydroxybutyrate/acetoacetate and lactate were the most frequent biochemical abnormalities. Muscular biopsy in light microscopy showed in most cases abnormal lipid storage.