Mitochondrial respiratory chain deficiency revealed by hypothermia.

We observed a 17-month-old girl with profound and initially isolated episodes of hypothermia. Thereafter, she developed growth delay, repetitive corneal and bone lesions. Persistent hyperlactataemia in plasma and in CSF prompted us to investigate respiratory chain enzymes. A deficit in respiratory chain complexes III and IV was demonstrated in isolated skeletal muscle mitochondria, circulating lymphocytes and fibroblasts by spectrophotometric and polarographic studies. Moreover, UCP3 mRNA expression in muscle was decreased.