Mitochondrial DNA point mutation T9176C in Leigh syndrome

Leigh syndrome is a progressive neuro degenerative disease frequently assoc iated with mitochondrial abnormalities. The mitochondrial DNA T9176C mutati on in the adenosine triphosphatase 6 gene has recently been described as a cause of Leigh syndrome. Leukocyte DNA from 59 children with Leigh syndrome was screened for the T9176C mutation by conventional polymerase chain reac tion methods. Two unrelated patients were found to be homoplasmic for this mutation in blood. Both patients had similar clinical and biochemical featu res. They had first presented acutely at 3 and 5 years, respectively, with ataxia and slurred speech. Magnetic resonance imaging changes were consiste nt with Leigh syndrome, and the cerebrospinal fluid lactate was elevated. T hey have both had relatively stable disease since the time of diagnosis. Th e mother of one of the children had presented at age 29 years with sudden o nset of ataxia, headache, and blurred vision. She was heteroplasmic for the T9176C mutation. The T1976C is an important cause of Leigh syndrome especi ally in the subgroup of patients with more stable disease and normal respir atory chain enzyme analysis.