This report from France illustrates the importance and value of coenzyme Q10 (ubiquinone), especially concerning respiratory function.

• The authors note that the respiratory-chain deficiencies are a broad group of largely untreatable diseases.

• There is a subclass of patients with these disorders who suffer from a coenzyme Q10 deficiency.

• Deficiency of coenzyme Q10-dependent respiratory-chain activities was identified in muscle biopsy, circulating lymphocytes, and cultured skin fibroblasts of 2 siblings with this disorder.

• Undetectable coenzyme Q10 in cultured fibroblasts supported the diagnosis of widespread coenzyme Q10 deficiency.

• The patients were treated with oral CoQ10 (5 mg/kg daily), which resulted in a substantial improvement of their condition over 3 years of therapy.

The authors conclude that particular attention should be paid to the fact that some patients with respiratory-chain enzyme deficiency may be successfully treated by oral CoQ10.

Lancet August 18, 2000; 356: 391-95