Myogenic Hyperuricemia: A Comparative Study between Type V and Type VII Glycogenosis

Glycolysis subsequent to glycogen breakdown is one of the major energy(ATP)-generating systems necessary for muscle exercise. The metabolic process of glycolysis depends on the functional integrity of many enzymes. Glycogenosis types V and VII are genetic errors resulting in deficiencies of muscle phosphorylase and muscle phosphofructokinase, respectively. Patients with these diseases have common muscle symptoms such as easy fatigability, stiffness and pain during exercise. Hyper-uricemia or gout has been documented in some patients with glycogenosis types V and VII. We recently showed that excess purine degradation in exercising muscles due to impaired glycolysis or glycogen breakdown causes hyperuricemia (myogenic hyperuricemia) in these patients (Kono et al., 1986; Mineo et al., 1987). Interestingly, the incidence of hyperuricemia seems to be far greater in type VII than in type V. At least 9 of 26 patients with glycogenosis type VII have been reported to be hyperuricemic (Agamanolis et al., 1980; Hays et al., 1981; Zanella et al., 1982; Vora et al., 1983; Mineo et al., 1985; Fogelfeld et al., 1985; Kono et al., 1986). However, only a few among more than 100 patients with type V have been reported to be hyperuricemic (Hardiman et al., 1987; Kono et al., 1987). In order to elucidate the metabolic basis for the different incidence of hyperuricemia, we compared purine degradation in exercising muscles between type V and type VII glycogenosis.