RESUMEN
BACKGROUND: Glycogen storage diseases (GSDs) are a collection of disorders related to glycogen synthesis or degradation that classically present in infancy with hypoglycemia, failure to thrive and hepatomegaly; however, their phenotype can vary significantly. CASE PRESENTATION: We present the cases of two children, 5 years old and 3.5 years old, who were referred to endocrinology for short stature. They were ultimately found to have hepatomegaly, fasting hypoglycemia, mild elevation of transaminases and ketosis. Laboratory and genetic studies were consistent with double heterozygosity for GSDs Ia and III, with one novel mutation discovered in each patient. Nightly, both children were treated with cornstarch, which resulted in resolution of laboratory abnormalities and improvement in their growth velocity. These cases are unusual in that GSD was diagnosed relatively late in life in patients with no previous history of severe hypoglycemia. CONCLUSIONS: They highlight the importance of considering glycogen storage disease in a child presenting with short stature, as it is a treatable disease that can be diagnosed non-invasively with genetic testing.