A patient with glycogen storage disease type 0 and a novel sequence variant in : a case report and literature review.

Glycogen storage disease type 0 (GSD0) is an autosomal recessive disorder caused by a sequence variant in the gene, leading to decreased or absent activity of hepatic glycogen synthase. With a frequency of less than 1 in 1,000,000 individuals, GSD0 represents only around 1% of all glycogen storage disease cases but it might be underrecognized. A 13monthold girl of reportedly unrelated parents presented with a decreased level of consciousness, twitching in her left cheek, and munching. During a fasting test, hyperketotic hypoglycemia was found. A novel homozygous gene sequence variant p.Thr445Arg was later confirmed by next-generation gene sequencing. After establishing a cornstarch- and protein-rich diet, the hypoglycemic episodes subsided and the patient's neurocognitive development was normal. To date, only 39 patients with 24 disease-causing gene variants have been identified in GSD0, and we review their characteristics. Because of the heterogeneous phenotypes, GSD0 is an underdiagnosed disorder. In patients with hyperketotic hypoglycemia and postprandial hyperglycemia, gene analysis should be performed.