Glycogen Storage Disease Type II, also known as Pompe disease, is a rare genetic disorder caused by a deficiency of the enzyme acid alpha-glucosidase. This enzyme is essential for breaking down glycogen, a stored form of glucose, into usable energy. Without it, glycogen accumulates in the body's cells, particularly in the muscles and heart, leading to various health issues. Symptoms of Pompe disease can vary widely, ranging from muscle weakness and respiratory problems to heart enlargement. The severity of the disease often depends on the age of onset, with infantile forms being more severe than late-onset forms. Early diagnosis and treatment, including enzyme replacement therapy, can help manage symptoms and improve quality of life.