Glycogen storage disease (GSD) type IX and growth hormone (GH) deficiency cause ketotic hypoglycemia via different mechanisms and are not known to be associated. We describe a patient presenting with severe ketotic hypoglycemia found to have both GSD IX and isolated GH deficiency.
A 3-year-and-11-month-old boy with a history of prematurity, autism, developmental delay, seizures, and feeding difficulty was admitted for poor weight gain and symptomatic hypoglycemia. He was nondysmorphic, with a height of 93.8 cm (2%, –1.97 SDS), and has no hepatomegaly. He developed symptomatic hypoglycemia, with a serum glucose level of 37 mg/dL after 14 h of fasting challenge. Critical sample showed a GH of 0.24 ng/mL. GH provocative stimulation testing was done with a peak GH of 2.8 ng/mL. Brain magnetic resonance imaging showed a hypoplastic pituitary gland. Given the clinical symptoms, suspicion for mitochondrial disease was high. Dual Genome Panel by Massively Parallel Sequencing revealed a hemizygous variant c.721A>G (p1241V) in the X-linked PHKA2 gene, a causative gene for GSD IX. Red blood cell PhK enzyme activity testing was low, supporting the diagnosis.
Given the patient’s developmental delays that were not explained by GH deficiency alone, further investigation showed two unrelated conditions resulting in deranged metabolic adaptation to fasting leading to severe hypoglycemia.
Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.
Research funding: None declared.
Employment or leadership: None declared.
Honorarium: None declared.
Competing interests: The funding organization(s) played no role in the study design; in the collection, analysis, and interpretation of data; in the writing of the report; or in the decision to submit the report for publication.
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