What is GSD?
Type II Glycogen Storage Disease
Overview:
- Synonyms: Acid Maltase Deficiency (AMD), Pompe Disease
- Cause: Deficiency of acid alpha-glucosidase (GAA) enzyme
- Category: Glycogen Storage Disease & Lysosomal Storage Disorder
- Effect: Glycogen builds up in lysosomes, damaging muscle cells—especially heart and skeletal muscles
Subtypes:
| Subtype | Age of Onset | Features |
| Infantile | Before 8 months |
Severe muscle weakness Cardiomyopathy Respiratory failure |
| Late-onset | After 1 year of age |
Progressive muscle weakness Less heart involvement |
Symptoms:
- Muscle weakness (limbs, trunk, diaphragm)
- Difficulty walking, climbing stairs
- Breathing problems, especially at night
- In infantile form: heart failure and early death without treatment
Diagnosis:
- Enzyme testing: Measures GAA activity via blood, muscle, or skin cells
- Genetic testing: Identifies mutations in the GAA gene
- Muscle biopsy: May show glycogen buildup in lysosomes (not always diagnostic)
Treatment:
- Enzyme Replacement Therapy (ERT): IV infusions of synthetic GAA
- Supportive care: Respiratory support (BiPAP/ventilator), physical therapy, nutrition
- Multidisciplinary team: Includes pulmonology, cardiology, neurology, genetics, and rehab specialists
Prognosis:
- Early diagnosis and ERT improve outcomes
- Respiratory failure is the leading cause of death in late-onset cases
- Lifelong management is essential for quality of life
