Sometimes, in addition to tissue biopsy and analysis, genetic testing can help doctors to reach a correct diagnosis of the type of amyloidosis present. Genetic testing involves examination of the DNA from the patient’s cells. These tests are performed on blood samples taken from the patient’s vein.
These techniques can identify mutations (abnormalities) in the genes responsible for the formation of proteins that may be amyloidogenic . This is helpful in hereditary types of amyloidosis.
Genetic tests can identify :
- Which gene is affected, providing information regarding which amyloid precursor protein formed the fibrils.
- Precisely which abnormality (mutation) is present in the affected gene, which may provide information about the likely clinical course.
For example, a mutation may be detected in the TTR gene. This means that the amyloidosis is of ATTR type. There are over 100 known mutations in this gene, and different mutations lead to different types of disease. For example the most common mutation worldwide, the Val30Met mutation, leads to amyloid deposits predominantly affecting the nerves. In contrast, the Val122lle mutation usually leads to amyloid deposits just in the heart, not in the nerves.
The Jack O’Neill Laboratory of Amyloidosis Research and Diagnosis at the National Amyloidosis Centre provides a comprehensive molecular diagnostic service for hereditary amyloidosis and hereditary systemic auto-inflammatory diseases (also known as hereditary periodic fever syndromes). See here for further information about logistics of genetic testing and a list of the genes that can be tested at the National Amyloidosis Centre.