DEFICIENCY OF RESPIRATORY-CHAIN COMPLEX-I IS A COMMON-CAUSE OF LEIGH-DISEASE

We reviewed the clinical features and etiologies of Leigh disease in 6 6 patients from 60 pedigrees. Biochemical or molecular defects were id entified in 50% of all pedigrees, and in 74% of the 19 pedigrees with pathologically proved Leigh disease. Isolated deficiency of respirator y chain complex I was found in 7 patients, though the complex was only assayed in 25 patients, making this the second most common biochemica l abnormality after complex TV deficiency. Mutations at residue 8993 o f mitochondrial DNA were found in only 2 patients. No correlation was found between the clinical features and etiologies. No defects were id entified in the 8 patients with normal lactate concentrations in the c erebrospinal fluid.