Description of the first two cases of Pompe disease in Bulgaria

Introduction Pompe disease is a rare, metabolic, multi-system, lysosomal storage disorder with autosomal recessive inheritance, caused by a deficiency of the glycogen-degrading lysosomal enzyme, acid alpha-glucosidase (GAA). Great phenotypic variability has led to the classification of several subtypes: infantile, late-infantile, childhood, juvenile, and adult-onset form, based on the age of onset and degree of organ involvement. In the most severe cases, disease onset is in infancy and death results from cardiac and respiratory failure along with muscle weakness within the first one or two years of life. In the milder, late-onset forms, muscle weakness is the primary symptom. Weakness of respiratory muscles is the major cause of mortality in these cases.