Phosphorylase deficiency associated with isometric exercise intolerance

SAHN, LEONARD M.D.
MAGEE, KENNETH R. M.D.

From the Department of Neurology, University of Michigan Medical Center, Ann Arbor.

Requests for reprints should be addressed to Dr. Magee, Department of Neurology, University of Michigan Medical Center, Ann Arbor, Ml 48104.

Received for publication October 20, 1975.

Neurology 26(9):p 896-898, September 1976.

Article abstract

In the patient reported here, most of the clinical and biochemical correlates of McArdle's disease were present; however, symptoms developed after isometric rather than after isotonic exercise. Histochemical reactions and assay of muscle homogenates confirmed the absence of phosphorylase; however, venous serum lactate increased in the arm after isometric and isotonic ischemic exercise, although the increase was significantly less than in a normal control. Although the symptoms differ significantly from those in McArdle's disease, this disorder could be a variant.