What Your Test Results Mean:

Carriers typically show no symptoms of Pompe disease; however, carriers are at an increased risk of having a child with Pompe disease. Risk for the current or future pregnancies is dependent on your partner’s carrier status. Carrier testing of your partner is recommended in addition to consultation with a genetic counselor.

Disease Explained:

Pompe disease is an inherited disorder characterized by muscle weakness and breathing problems. In this disorder, affected individuals cannot break down glycogen due to a shortage of the enzyme acid alpha-glucosidase. Glycogen then builds up to toxic levels in the lysosomes, damaging the body’s organs and tissues. There are three types of Pompe disease: classic infantile-onset, non-classic infantile-onset, and late-onset. The classic infantile-onset form is characterized by muscle weakness, poor muscle tone, hepatomegaly, and heart defects. Affected infants begin to have symptoms within the first few months of life, and experience a failure to thrive. Non-classic infantile-onset is characterized by delayed motor skills and progressive muscle weakness. Affected individuals usually die early in childhood. Late-onset Pompe disease is much milder and less severe than the infantile-onset forms. It is characterized by progressive muscle weakness and breathing problems that may lead to respiratory failure. Enzyme replacement therapy is clinically available for individuals with this disorder. Management is typically overseen by a group of metabolic specialists.

How the Genetics Works:

Pompe disease is an autosomal recessive glycogen storage disorder caused by pathogenic variants in the GAA gene. In general, individuals have two copies of the GAA gene. Carriers of Pompe disease have a single variant in one copy of the GAA gene, while individuals with Pompe disease have variants in both copies of the GAA gene, one inherited from each parent. Risk for two carriers to have a child with the disorder is 25%.