Findings in muscle in complex I (NADH coenzyme Q reductase) deficiency

Publisher Website
Google Scholar
Abstract
Thirteen of 15 patients with complex I deficiency had the multisystemic form, with strokelike episodes and other symptoms that fulfilled the diagnostic requirements for MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes), and 2 had only muscle fatigability and weakness, having the purely myopathic form. In the multisystemic form, 12 patients had ragged-red fibers. All multisystemic patients had myopathic histochemical abnormalities that consisted of mild to moderate variation in fiber size (13), disorganized intermyofibrillar networks (12), type 2 fiber atrophy (10), and an increased number of type 2C fibers (9). Five of 13 multisystemic patients had Decemberreased cytochromec oxidase (CCO) activity in extrafusal fibers, with sparing of intrafusal muscle fibers. In the myopathic form, pathological findings were similar to those in the multisystemic form. In addition to complex I and NADH dehydrogenase activities being Decemberreased, the CCO activity was significantly Decemberreased (less than 50% of control value) in 8 patients, especially when the disease was in its advanced stages, suggesting that CCO enzyme might be secondarily affected as the disease progresses.