[McArdle disease: differential diagnosis of the increase in creatine kinase induced by the exercise test].

In a Turkish couple presenting atypical precordial pain, muscle pain and a massive increase of creatine kinase during and one day after bicycle ergometry, suspicion of McArdle's disease was confirmed by a pathologic ischemic forearm worktest, a pathologic serial stimulation test and by pathologic glycogen content with lack of myophosphorylase activity on histochemical examination of thigh muscle tissue. Characteristic signs of McArdle's disease such as muscle weakness, muscle pain and muscle swelling, especially after exertion, were detected only after specific questioning of the patients. McArdle's disease was also detected by phosphor nuclear resonance in the two male children. Frequent consanguinity in the small isolated mountain village where the family originated explains why all four members of two generations are affected by the autosomal recessive disease.