[Morphological and biochemical studies on glycogenosis type V (McArdle) (author's transl)]

This report deals with structural and biochemical studies of muscle biopsies from six patients with glycogenosis type V (McArdle). From a morphological point of view in four cases the typical findings of vacuolar myopathy with glycogen storage especially under the sarcolemma can be demonstrated. One biopsy shows only mild structural changes which without additional biochemical analysis could be overlooked. In one case signs of recovery phase after rhabdomyolysis predominate the storage myopathy. Biochemical studies in all cases show an elevated glycogen content (2.5-4.23%). Only the from a clinical point of view most expressive patient with recurrent episodes of rhabdomyolysis exhibits a glycogen storage over 5%. All cases additionally show an absence or highly reduction of phosphorylase activity. Apart from the most expressive clinical course the extent of morphological and biochemical findings is not clearly correlated. Therefore if clinical signs suggest the diagnosis of glycogenosis type V it appears necessary to perform additional biochemical examination of muscle biopsy independent from the degree of morphological anomalies.