Glycogen storage disease type II overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Anmol Pitliya, M.B.B.S. M.D.[2]
Overview
Historical Perspective
In 1932, J.C. Pompe, a Dutch pathologist described "idiopathic hypertrophy of the heart" as a post-mortem finding in a 7-month-old girl. This was later confirmed as glycogen storage disease type 2. In 2006, enzyme replacement therapy (ERT) with recombinant human acid alpha-glucosidase (rhGAA, alglucosidase alpha) was approved by the US Food and Drug Administration (FDA) for patients with infantile-onset GSD type 2.
Classification
Glycogen storage disease type II may be classified according to the age of onset and presence of cardiomegaly into 2 subtypes including infantile-onset Pompe disease (IOPD) and late-onset Pompe disease (LOPD).
Pathophysiology
Glycogen storage disease type 2 (GSD type 2) results due to deficiency of lysosomal enzyme acid α-glucosidase (GAA). GSD type 2 is the most severe type of GSD leading to death in earlier stages of life. Deficiency of GAA leads to accumulation of glycogen in lysosomes of various tissues, most commonly in cardiac, skeletal, and smooth muscle cells. There is a progressive accumulation of glycogen and its substrates in tissues leading to debilitation, organ failure and finally death. GSD type 2 follows an autosomal recessive pattern. GAA gene mutation responsible for lysosomal enzyme acid α-glucosidase (GAA) deficiency in GSD type 2 and is located on chromosome locus 17q25. On gross pathology, characteristic findings of glycogen storage disease type 2 include cardiomegaly and myopathy. On microscopic histopathological analysis, characteristic findings of glycogen storage disease type 2 include muscle has PAS-positive (diastase sensitive) vacuoles.