Mitochondrial T9957C mutation in association with NAION and seizures but not MELAS.
OBJECTIVE
To assess the functional significance of the mitochondrial nt-9957 mutation in a man with non-arteritic ischemic optic neuropathy (NAION). This nt-9957 mutation has been previously reported in association with mitochondrial encephalopathy, lactic acidosis, and stroke-like events (MELAS).


METHODS
The patient was examined clinically and with magnetic resonance imaging and spectroscopy. The entire coding region of the mitochondrial genome was sequenced, and mitochondrial function was assessed by flow cytometry after staining with fluorescent dihydroethidium.


RESULTS
This 76-year-old man had optic nerve disease bilaterally and seizures, but no clinical or radiological evidence of MELAS. He had no mitochondrial DNA mutation other than the 9957. Functional testing revealed a severe defect in mitochondrial complex III activity.


CONCLUSIONS
This patient had a mitochondrial functional deficit consistent with his 9957 mutation. It seems quite likely that this mutation may be responsible for optic nerve and brain injuries.
Abu-Amero
Khaled K
KK
Department of Genetics, King Faisal Specialist Hospital and Research Centre (MBC-03), P.O. Box 3354, Riyadh 11211, Saudi Arabia. kamero@kfshrc.edu.sa
Bosley
Thomas M
TM
Bohlega
Saeed
S
Hansen
Erik
E
D016022:Case-Control Studies; D004272:DNA, Mitochondrial / Q000235:genetics*; D004996:Ethidium / Q000031:analogs & derivatives*; D005434:Flow Cytometry; D006801:Humans; D017241:MELAS Syndrome / Q000175:diagnosis / Q000235:genetics*; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D009154:Mutation / Q000235:genetics*; D018917:Optic Neuropathy, Ischemic / Q000175:diagnosis / Q000235:genetics*; D012640:Seizures / Q000235:genetics*
D004272:DNA, Mitochondrial; C067883:dihydroethidium; D004996:Ethidium