A T-TO-G MUTATION AT NUCLEOTIDE PAIR-8993 IN MITOCHONDRIAL-DNA IN A PATIENT WITH LEIGHS SYNDROME

We studied a patient with Leigh's syndrome using neurophysiologic, rad iologic, enzymatic, biochemical, and molecular analysis. Her clinical course had started with acute encephalopathic symptoms at 7 months of age. With repeated remission and exacerbation, she developed hypotonia and symptoms of brainstem dysfunction, such as irregular respiration and swallowing difficulty. These symptoms were followed by epileptic s eizures, including simple partial seizures and tonic spasms. Both seru m lactate and serum pyruvate levels were elevated, and deficient activ ity was detected in cytochrome c oxidase in her quadriceps femoris mus cle. From the early stages, we noted an abnormality in the auditory br ainstem response and visual evoked potentials, and an abnormal symmetr ical low-density area in the basal ganglia on the computed tomographic scan. We found a mitochondrial DNA point mutation at 8993 in blood sa mples from both the patient and her mother using a simple polymerase c hain reaction method. The ratio of wild and mutant mitochondrial DNA c alculated densitometrically on polymerase chain reaction products was 56.6% in the patient's blood cells and 8.4% in her mother's. This pati ent's disorder was thought to be maternally inherited Leigh's syndrome . Her brother had died of the identical clinical features at 1 year 9 months of age.