title: Diagnosis of glycogenosis type II.
abstract: The diagnosis of glycogenosis type II is often complicated by the rarity of the condition and the heterogeneity of the clinical manifestations of the disease. It is a progressive, debilitating, and often fatal neuromuscular disorder that manifests as a continuum of clinical phenotypes, which vary with respect to organ involvement, age at onset, and severity. Early diagnosis requires both increased awareness among physicians regarding the clinical characteristics of the disease and fast and reliable acid alpha-glucosidase (GAA) enzyme activity assays to confirm the GAA deficiency. The clinical diagnosis of glycogenosis type II is confirmed by virtual absence (found in infants) and marked reduced activity (found in juveniles and adults) of GAA enzyme in blood samples, cultured fibroblasts, and muscle biopsies. This article specifically highlights the need for early recognition of the clinical manifestation of the disease in infants, juveniles, and adults. Descriptions of the main clinical features of the condition, as well as differential diagnosis are included. In addition, the tests required for a confirmed diagnosis are described, and use of muscle imaging to evaluate muscle pathology is reviewed.
authors.affiliation: Regional Coordination Centre for Rare Diseases, University Hospital Santa Maria della Misericordia of Udine, Udine, Italy.
authors.forename: B
authors.initials: B
authors.lastname: Bembi
authors.forename: E
authors.initials: E
authors.lastname: Cerini
authors.forename: C
authors.initials: C
authors.lastname: Danesino
authors.forename: M A
authors.initials: MA
authors.lastname: Donati
authors.forename: S
authors.initials: S
authors.lastname: Gasperini
authors.forename: L
authors.initials: L
authors.lastname: Morandi
authors.forename: O
authors.initials: O
authors.lastname: Musumeci
authors.forename: G
authors.initials: G
authors.lastname: Parenti
authors.forename: S
authors.initials: S
authors.lastname: Ravaglia
authors.forename: F
authors.initials: F
authors.lastname: Seidita
authors.forename: A
authors.initials: A
authors.lastname: Toscano
authors.forename: A
authors.initials: A
authors.lastname: Vianello
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D019411:Clinical Laboratory Techniques / Q000592:standards; D003937:Diagnosis, Differential; D042241:Early Diagnosis; D006009:Glycogen Storage Disease Type II / Q000175:diagnosis* / Q000201:enzymology / Q000503:physiopathology; D006801:Humans; D007231:Infant, Newborn; D054792:Muscle, Striated / Q000201:enzymology / Q000473:pathology / Q000503:physiopathology; D009135:Muscular Diseases / Q000175:diagnosis / Q000201:enzymology / Q000503:physiopathology; D010641:Phenotype; D000520:alpha-Glucosidases / Q000032:analysis / Q000097:blood / Q000172:deficiency
chemical_list: D000520:alpha-Glucosidases