[Nation-wide survey on muscle glycogen storage disease (MGSDs) and comparison with our experiences in diagnosis of MGSDs].

To clarify the actual frequency of each type of muscle glycogen storage diseases (MGSDs) in Japan, we performed nation-wide survey in 2001. We compared the results with our diagnostic experiences at Hamamatu City Medical Center for Developmental Medicine. The majority (approximately 80%) of the MGSDs consisted of type II, V and III in Japan. In our experiences, most of the patients were diagnosed by the assays of glycolytic enzyme activities using biopsied skeletal muscles. However, the biochemical diagnoses of MGSDs type II, III, IV, and IX can be made using blood samples. Additionally, common genetic mutation (708/709 delTTC) of myophosphorylase gene has been found approximately in 50% of the Japanese patients with MGSDs type V. Therefore, approximately 70% of the MGSDs may be diagnosed by biochemical and genetic analysis using blood samples. Additional survey on McArdle's disease showed that the onset of muscle symptoms in McArdle's disease were variable, however, fixed muscular symptoms such as muscle weakness and muscle atrophy were present in 45% of patients.