Canine α-glucosidase deficiency (Type II glycogenosis; juvenile Pompe disease) is a rare autosomal-recessive genetic lysosomal storage disease characterized by α-glucosidase deficiency as widespread organomegaly.
This canine disease is caused by a missense mutation in the GAA gene which is responsible for production of α-glucosidase that normally degrades α-1,4 and α -1,6 linkages in glycogen, maltose, and isomaltose. As a consequence, the catalytically inactive alpha-glucosidase cannot convert glycogen, maltose and isomaltose into subunits and accumulates within cytosolic lysosomes, leading to cell death and eventual tissue destruction.
Over the course of months, a range of progressive clinical symptoms manifests due to muscle weakness.
Clinically affected dogs are usually under 2 years of age with a long history of anorexia, dysphagia, vomiting, progressive weakness, weight loss and heart murmurs.
Ultrasonography usually reveals esophageal dilatation characteristic of megaesophagus, hepatomegaly and cardiomegaly suggestive of hypertrophic cardiomyopathy. Blood tests typically show decreased ALP and elevated ALT, BUN and thrombocytosis.
Histological examination of biopsies usually reveals accumulation of glycogen-containing vacuoles in the cerebral cortex, liver, myocardium and oesophageal smooth muscle.
Diagnosis is usually based on biochemical testing of tissue samples for alpha-glucosidase activity, which is markedly reduced.
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