A Myopathy Due to Glycolytic Abnormality

IN 1951, McArdle1described a case characterized by a life-long history of exercise intolerance, muscle pain and stiffness with exertion, and no lactate formation during exercise. He postulated that this disease was due to a defect in glycogen breakdown; later, in 1959, deficiency of muscle phosphorylase was proven in similar cases biochemically and histochemically.2,3 As knowledge of the various enzymes in glycolytic pathway was accumulated, the possibility of various enzymatic defects other than amylophosphorylase could well be considered. In fact, several enzyme defects including phosphoglucomutase were suspected in a case of Thompson et al,4and an almost complete absence of phosphofructokinase in muscle was found in the patients of Tarui and his associates.5 Meanwhile, Larsson and his colleagues6described a hereditary disease with paroxysmal myoglobinuria characterized by low physical performance with easy fatigability, dyspnea, and palpitation starting in childhood. They considered that the disease