Abstract

McARDLE'S syndrome,1 an inborn error of metabolism caused by a lack of glycogen phosphorylase activity in skeletal muscle, is a recessive condition of some rarity.2 Nevertheless, it poses a constant problem in the differential diagnosis of all forms of muscular disorder. Patients usually present with this condition after a long history of inability to sustain exercise; the diagnosis is suggested by the demonstration that ischemic exercise (the forearm-exercise test2) fails to generate lactic acid, and it is confirmed after open-muscle biopsy by the histochemical demonstration of excess glycogen and absent phosphorylase. A conclusive diagnosis and further clarification of various . . .