• Overview
• Inheritance
• Symptoms
  • The Kidney
  • The Brain and Nerves
  • The Heart
  • The Eyes
  • The Skin
  • The Digestive Tract
• Testing
• Treatment
• Resources

Enzyme testing

Diagnosis
The diagnosis of Fabry disease is made based on the results of a blood test that measures the level of a-galactosidase A enzyme activity. In people with Fabry disease, the amount of enzyme activity is much lower than normal.

Carrier testing
Enzyme testing is not as reliable for detecting Fabry carriers, since some carriers have a a-galactosidase A level in the normal range. When a female's enzyme level is normal, an eye exam to look for corneal whorling may help to clarify her Fabry carrier status.

DNA testing
DNA testing, also done on the blood, can detect a-galactosidase A gene mutations that cause Fabry disease. DNA testing is not generally done to diagnose Fabry disease; however, it may be useful to confirm a diagnosis made by enzyme testing. DNA test results do not necessarily relate to the severity of the disease or to a person's specific symptoms, and the test result will not change medical treatment.

Identifying which Fabry gene mutation is present in an affected person may also be helpful to other family members who wish to know if they are a carrier of the same mutation. Carrier testing is available to relatives of people with Fabry disease.

Prenatal diagnosis of Fabry disease may be available in pregnancies involving a male fetus known to be at risk.

DNA testing for Fabry disease is performed only in some specialized genetics laboratories. Generally, people who have DNA testing first meet with a genetic counselor, who can explain the testing in more detail and answer any questions. The genetic counselor can also help explain the test results, once they are available. Cindy Johnston, MS is a genetic counselor at the Center; she is available to meet with patients to discuss DNA testing and other genetic issues.