GENERALIZED GLYCOGEN-STORAGE AND CARDIOMEGALY IN A KNOCKOUT MOUSE MODEL OF POMPE-DISEASE

Glycogen storage disease type II (GSDII; Pompe disease), caused by inh erited deficiency of acid alpha-glucosidase, is a lysosomal disorder a ffecting heart and skeletal muscles, A mouse model of this disease was obtained by targeted disruption of the murine acid alpha-glucosidase gene (Gaa) in embryonic stem cells. Homozygous knockout mice (Gaa -/-) lack Gaa mRNA and have a virtually complete acid alpha-glucosidase de ficiency, Glycogen-containing lysosomes are detected soon after birth in liver, heart and skeletal muscle cells, By 13 weeks of age, large f ocal deposits of glycogen have formed, Vacuolar spaces stain positive for acid phosphatase as a sign of lysosomal pathology, Both male and f emale knockout mice are fertile and can be intercrossed to produce pro geny The first born knockout mice are at present 9 months old, Overt c linical symptoms are still absent, but the heart is typically enlarged and the electrocardiogram is abnormal, The mouse model will help grea tly to understand the pathogenic mechanism of GSDII and is a valuable instrument to explore the efficacy of different therapeutic interventi ons.