ADVANCED RESEARCH IN GASTROENTEROLOGY & HEPATOLOGY JUNIPER PUBLISHERS Abstract Background: One of the GSDs that principally affect the liver is Type 1 GSD. GSDI patients may present with fast-induced hypoglycemia and hyperlactacidemia. More commonly, the first symptom is the presence of a protruded abdomen due to marked hepatomegaly. Study aims: This study aims to assess frequency, clinical manifestations, biochemical features of GSD1 in children attending University Hospitals in Upper Egypt, and to identify the possible role of plasma biotinidase in diagnosis of GSD-1 in these children. Patients and Methods: Any child with unexplained hepatomegaly with growth retardation, early fasting hypoglycemia, hyperuricemia, or hyperlipidemia during the period from July 1st 2011 up to December 31st 2013 was included in this study. Complete blood counts, liver function tests, Prothrombin time and concentration, serum glucose, cholesterol, triacylglycerol, plasma ...