In a recent study, Paula Hernández-Arévalo, Hospital Universitario Virgen del Rocío, Seville, Spain, and colleagues sought to identify genetic variations and clinical features using 2637 samples of patients with symptoms or susceptible signs of Pompe disease. From 17 diagnosed patients, 14 variants were identified, with 4 previously undescribed genetic variants. All exhibited decreased α-glucosidase activity. A homozygous c.236_246delCCACACAGTGC pathogenic variant was associated with early disease and a worse prognosis.