ESPE Abstracts

Background: Glycogen-storage disease type VI (GSD VI) is an autosomal recessive disorder due to deficiency of the liver isoform of phosphorylase resulting in abnormal accumulation of glycogen. Patients typically present in early childhood with growth retardation, hepatomegaly, hypoglycaemia and ketosis. Ketotic hypoglycaemia is a relatively common diagnosis (of exclusion) in children presenting with hypoglycaemia.

Case: A 3-year-old girl presented with an episode of collapse and hypoglycaemia. She had an uneventful past medical history and was born at term to non-consanguineous Caucasian parents. She did not have any intercurrent illness. She had a normal examination with no dysmorphic features or hepatomegaly. The hypoglycaemia screen revealed appropriately suppressed insulin, low c-peptide and elevated free fatty acids and ketones, and normal cortisol suggesting a diagnosis of ‘ketotic hypoglycaemia’. The plasma amino acids, ammonia, lactate, acylcarnitine profile and urine organic acids showed no abnormalities. She was noted to have short stature (height −2.5 SDS) and further endocrine evaluation revealed normal thyroid function, bone profile, prolactin, 46,XX karyotype, and low IGF1. The glucagon stimulation test revealed a suboptimal growth hormone response of 4.7 μg/l; hence she was commenced on GH. She continued to have symptomatic hypoglycaemic episodes and repeated hypoglycaemia screen demonstrated ketosis. In view of the persistent ketotic hypoglycaemic episodes, not necessarily triggered by intercurrent illness, further genetic analysis was undertaken using a targeted sequencing panel. This revealed a heterozygous PYGL mutation (c.1900G>C) suggesting a possible diagnosis of GSD VI.

Conclusion: We report a case of GSD VI who presented with recurrent ketotic hypoglycaemia and did not have hepatomegaly on clinical examination. As ketotic hypoglycaemia is a diagnosis of exclusion, it is important to consider alternative diagnoses especially in the presence of recurrent hypoglycaemic episodes and short stature. Genetic evaluation may be warranted in selected cases of ketotic hypoglycaemia.