Given the clinical picture and the early detection of septal and biventricular hypertrophy, genetic testing was performed, revealing a homozygous c.2560 C > T variant in the acid alpha-glucosidase gene (both parents were carriers), described in scientific literature as a class 5 pathogenic variant associated with glycogenosis type II (Pompe disease). Here, GAA is linked to Glycogen storage disease due to acid maltase deficiency.