The GAA gene encodes instructions for the production of an enzyme called acid alpha-glucosidase, also known as the GAA enzyme.This enzyme is used in lysosomes, which are intracellular compartments that serve as recycling centers. Lysosomes use digestive enzymes to break down complex sugar molecules into simpler ones that can be used for energy.
If both parents are carriers of a mutated GAA gene, the baby has a 25% chance of inheriting two copies of the nonworking GAA gene, leading to Pompe disease. The infant also has a 50% chance of becoming a Pompe disease carrier. If only one of the parents carries a mutated GAA gene, then the child will not develop the disease but has a 50% chance of carrying a mutated copy of the gene.
Mutations in the GAA gene are identified through genetic tests, often done by testing a sample of blood or saliva.
Both infantile-onset and late-onset Pompe disease are caused by mutations in the GAA gene, which results in symptoms including muscle weakness and delayed motor development. People with the most severe form of Pompe disease, classic infantile-onset, typically have mutations that lead to the absence or near-total absence of the GAA enzyme. In contrast, those with late-onset Pompe disease usually have mutations that allow more of the functional GAA enzyme to be produced.