T.P.28

Glycogen storage disease type V (GSD-V), also known as McArdle’s disease, is the most common disorder of muscle glycogenosis. Most adult patients present with typical clinical and laboratory features. However, there has only been one case report of Korean patients with GSD-V. Here, we report a Korean case of GSD-V with typical clinical and laboratory findings. A 32-year-old woman was referred to our clinic due to easy fatigability, muscle cramps and myoglobulinuria. Her family history was unremarkable. She recalled easy fatigability, muscle cramps and contractures after intense exercise during physical education classes since early adolescence. In addition, she had several episodes of dark urine following intense exercise such as long-distance running. She also reported marked improvement in exercise tolerance after about 20 min, a process termed the ‘second-wind phenomenon’; specifically, she had seen improvement in excessive fatigue, breathlessness, and tachycardia. Physical examination did not show any neurological abnormality, including fixed muscle weakness or atrophy. Serum creatine kinase level was 1161 IU/L at rest. The result of the non-ischemic forearm exercise test was compatible with GSD-V. Mutation analysis identified the compound heterozygous mutations of the PYGM, p.D510fs and p.F710del, which has not yet been reported in Korea. The present case recognizes that detail clinical and laboratory analysis is the first step in the diagnosis of GSD-V.