title: Exercise testing in late-onset glycogen storage disease type II patients undergoing enzyme replacement therapy.
abstract: Enzyme replacement therapy (ERT) has recently became available for patients with glycogen storage disease type II. Previous studies have demonstrated clinical efficacy of enzyme replacement therapy, however, data on physiological variables related to exercise tolerance are scarce. Four glycogen storage disease type II late-onset patients (45 ± 6 years) performed an incremental exercise on a cycle ergometer, up to voluntary exhaustion, before (BEFORE) and after 12 months of ERT (AFTER). Peak workload, oxygen uptake, heart rate, cardiac output (by impedance cardiography) and vastus lateralis oxygenation indices (by continuous-wave near-infrared spectroscopy, NIRS) were determined. Peak workload and oxygen uptake values significantly increased during ERT (54 ± 30 vs. 63 ± 31 watt, and 17.2 ± 4.4 vs. 19.7 ± 3.5 ml/kg/min, respectively, in BEFORE vs. AFTER). On the other hand, for both peak cardiac output (12.3 ± 5.3 vs. 14.8 ± 4.5L/min) and the NIRS-determined peak skeletal muscle fractional O(2) extraction, expressed as a percentage of the maximal values during a transient limb ischemia (30 ± 39% vs. 38 ± 28%), the observed increases were not statistically significant. Our findings suggest that in glycogen storage disease type II patients enzyme replacement therapy is associated with a mild improvement of exercise tolerance. The findings need to be validated during a longer follow-up on a larger group of patients.
authors.affiliation: Institute of Bioimaging and Molecular Physiology, CNR, Segrate Milano, Italy. mauro.marzorati@ibfm.cnr.it
authors.forename: Mauro
authors.initials: M
authors.lastname: Marzorati
authors.forename: Simone
authors.initials: S
authors.lastname: Porcelli
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Bellistri
authors.forename: Lucia
authors.initials: L
authors.lastname: Morandi
authors.forename: Bruno
authors.initials: B
authors.lastname: Grassi
mesh_terms: D000328:Adult; D017668:Age of Onset; D002302:Cardiac Output / Q000502:physiology; D056947:Enzyme Replacement Therapy / Q000379:methods; D005080:Exercise Test / Q000379:methods; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D006009:Glycogen Storage Disease Type II / Q000503:physiopathology* / Q000628:therapy*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D016896:Treatment Outcome; D000520:alpha-Glucosidases / Q000627:therapeutic use*
chemical_list: D000520:alpha-Glucosidases