[A case of complex I deficiency with episodic respiratory distress].
A 7-year-old girl with normal psychomotor development during infancy began to have easy fatigability about 3 years of age. At the age of 5 years, she developed respiratory distress and became unconscious when the serum lactate and pyruvate levels were markedly elevated and a blood gas analysis showed respiratory and metabolic acidosis. Thereafter, she had similar episodic respiratory problems with lactic acidosis. Her muscle biopsy showed a myopathic pattern and numerous ragged-red fibers in an approximately half of muscle fibers. Lipid droplets were slightly to moderately increased in amount mostly in the ragged-red fibers. A biochemical analysis on the isolated mitochondria from the biopsied sample showed markedly decreased NADH cytochrome c reductase activity with no specific but rather uniformly decreased subunits of complex I by the immunoblotting method. She was diagnosed as having the myopathic form of complex I deficiency because she and her relatives with similar muscle symptoms had no central nervous system symptoms such as progressive mental deterioration, convulsions and stroke-like episodes. Diagnosis of complex I deficiency was further confirmed by an oxograph study; the oxygen consumption was not detectable when malate and pyruvate were added as the substrates in the isolated mitochondria. Although stroke-like episodes and convulsions are commonly seen in complex I deficiency, episodic respiratory distress as seen in the present patient has not been described in the literature.
Tohyama
J
J
Department of Pediatrics, Nagaoka Red Cross Hospital.
Torigoe
K
K
Sato
S
S
Takahashi
R
R
Suda
M
M
Tojo
M
M
Nonaka
I
I
Koga
Y
Y
Tanaka
M
M
Ozawa
T
T
D002648:Child; D004579:Electron Transport; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008931:Mitochondria, Muscle / Q000378:metabolism; D009132:Muscles / Q000473:pathology; D016660:NAD(P)H Dehydrogenase (Quinone); D010101:Oxygen Consumption; D011808:Quinone Reductases / Q000172:deficiency*; D012131:Respiratory Insufficiency / Q000209:etiology* / Q000473:pathology
D016660:NAD(P)H Dehydrogenase (Quinone); D011808:Quinone Reductases