Pompe disease is inherited in an autosomal recessive pattern and is caused by changes in the GAA gene, which provides instructions for making the enzyme acid alpha-glucosidase. This enzyme helps break down glycogen (a form of stored sugar) in the lysosomes of cells. When the enzyme is missing or not working properly, glycogen builds up, especially in muscles, leading to damage.
Pompe disease is characterised by muscle weakness, breathing difficulties, and, in infants, heart problems. The condition can range from mild or even symptom-free in some people, to severe muscle weakness, heart failure, and breathing problems that can be life-threatening. Symptoms can appear at any age, from infancy to adulthood, and the severity and progression can vary widely—even within the same family. Some people may have only mild symptoms, while others develop serious complications early in life. The course of Pompe disease is generally unpredictable, and while some individuals remain stable for years, others may experience rapid progression and life-threatening complications, especially if symptoms begin in infancy.