Genetic testing confirms the diagnosis and informs about familial risk. Understand what the results mean and the options available.
Pompe disease is caused by mutations in the GAA gene (chromosome 17), which encodes the enzyme acid alpha-glucosidase. It is inherited in an autosomal recessive pattern, which means:
• Two mutated copies of the gene are needed to develop the disease (one from each parent)
• Carriers (a single mutated copy) generally do not show symptoms
• If both parents are carriers, each child has a 25% chance of being affected, a 50% chance of being a carrier and a 25% chance of not carrying the mutation
After a Pompe diagnosis, genetic counseling is recommended to:
• Understand the inheritance pattern and what it means for the family
• Identify at-risk relatives who could benefit from screening
• Provide information about reproductive options (prenatal diagnosis, preimplantation genetic diagnosis)
• Address the emotional impact of the genetic diagnosis
A genetic counselor is a specialized professional who can guide you through this process.
When a case of Pompe is identified in a family, it is recommended to offer screening to first-degree relatives (siblings, children, parents). This is called cascade screening and allows:
• Detection of pre-symptomatic cases that could benefit from early treatment
• Identification of carriers for family planning
• Reduction of anxiety for relatives who turn out not to be affected
Screening usually consists of a dried blood spot test (DBS) followed by genetic analysis if necessary.
Pompe is inherited in an autosomal recessive manner: both copies of the GAA gene must be mutated for the disease to appear. When both parents are carriers, each pregnancy has a 25% chance of an affected child, 50% healthy carrier and 25% non-carrier — regardless of previous pregnancies.
Prenatal diagnosis
Chorionic villus sampling (weeks 10-13) or amniocentesis (weeks 15-18) for fetal genetic analysis.
Preimplantation genetic diagnosis (PGD)
Analysis of IVF embryos to transfer only unaffected ones. Available at accredited centres.
Carrier screening
Genetic study of the couple before conception, especially if there is a family history.
Genetic counselling
Educational and supportive process with a clinical geneticist. Free within the Spanish public health system.
Being a carrier is no one's fault: it is information that lets you decide with autonomy.
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