The diagnosis of Fabry disease needs to be made as early as possible to help prevent painful and debilitating symptoms and permit patients and their families the appropriate medical care. Delayed diagnosis is often due to under recognition of the disease.

The clinical diagnosis can be based upon the presence of the cardinal Fabry symptoms or through a family history; a history of a family member, such as a maternal uncle or grandfathers who died early due to renal failure, a heart attack or stroke could also be a strong indicator.

Diagnosis is confirmed in males with a simple blod test for enzyme assay measuring the functional level of alpha galactosidase A enzyme. This test will disclose affected males but it is not reliable for detection of females. Lyonization will affect the interpretation of the AGAL due to the fact that different cells throughout the body will produce different amounts of the enzyme. Therefore, for female patients, a DNA sequence analysis is the most precise procedure to confirm the diagnosis. For patients with unknown causes for renal failure or LVH, a tissue biopsy is a simple procedure and a confirmatory test.