We systematically searched fetal and infantile cases in PubMed using following search strategy: ("Fetus"[Mesh] OR "Infant, Newborn"[Mesh] OR "Infant"[Mesh] OR fetus [TIAB] OR fetal [TIAB] OR neonat* [TIAB] OR newborn [TIAB] OR infant* [TIAB] OR baby [TIAB] OR babies [TIAB]) AND (PRKAG2 [TIAB] OR "AMP-Activated Protein Kinases"[Mesh] OR AMP-activated protein kinase [TIAB]) AND ("glycogen storage disease"[Mesh] OR "Cardiomyopathies"[Mesh] OR "Cardiomyopathy, Hypertrophic"[Mesh] OR cardiomyopathy [TIAB] OR hypertrophic cardiomyopathy [TIAB]). The gene discussed is PRKAG2; the disease is hypertrophic cardiomyopathy.