The significance of clinical and laboratory features in the diagnosis of glycogen storage disease type v: a case report

Abstract

Glycogen storage disease type V (GSD-V) is the most common disorder of muscle glycogenosis with characteristic clinical and laboratory findings. A 32-yr-old woman complained of exercise intolerance and myoglobulinuria since early adolescence. She reported several episodes of second-wind phenomenon. Physical examination did not show any neurological abnormality, including fixed muscle weakness or atrophy. Serum creatine kinase level was 1,161 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.

Keywords: Glycogen Storage Disease Type V; McArdle's Disease; Phosphorylase, Glycogen, Muscle (PYGM).

Fig. 1

Pedigree and Sequencing chromatograms in Korean patient with PYGM mutations. (A) Pedigree of a family with glycogen storage disease type V (GSD-V). Arrow indicates the proband, whose DNA was used for direct sequencing of PYGM. Filled symbol indicate affected member. (B) Sequencing chromatograms of PYGM mutations. One allele had a frameshift mutation of c.1531delG (p.D510fs) in exon 13 and the other allele had a deletion mutation of c.2128_2130delTTC (p.F710del) in exon 17.

Fig. 2

Non-ischemic forearm exercise test in a patient with GSD-V. The non-ischemic forearm exercise test showed no increase in venous lactate level with a normal increase in ammonia.