PRKAG2‐Related Lethal Congenital Glycogen Storage Disease of the Heart as Rare Cause of Fetal Hydrops With Bradycardia and Cardiomyopathy: Clinical Report and Literature Review

ABSTRACT Nonimmune foetal hydrops is a prenatal condition associated with significant perinatal mortality. It has so far been associated with over 200 chromosomal and monogenic conditions, most frequently chromosomal aneuploidies and RASopathies. Thorough clinical phenotyping and genetic evaluation are essential to determine the underlying etiology of this clinical entity and guide obstetrical and postnatal management. In this report, we describe the prenatal presentation and postnatal outcome of a pregnancy with Lethal Congenital Glycogen Storage Disease of the Heart, a rare autosomal dominant non lysosomal cardiac glycogenosis caused by a novel de novo likely pathogenic variant in the Protein Kinase AMP‐Activated Non‐Catalytic Subunit Gamma 2 (PRKAG2) gene, [NM_016203.3:c.1150A > G, p.(Arg384Gly)]. To this day, only six other molecularly confirmed prenatal presentations of this condition have been reported. This clinical report adds to the knowledge on the prenatal features, clinical evolution, molecular diagnosis and pathological findings of this disorder and underlines the clinical utility of comprehensive molecular testing in the investigation of nonimmune foetal hydrops and fetal cardiomyopathy.