Amyloidosis, Transthyretin-Associated Familial, Reflex, Blood

Casandra

Casandra Test Code MC95100Version 1 (DRAFT)

Performing Lab

Lab Mayo Clinic LabLab Test ID TTRXCPT Codes 81404, 82542

Amyloidosis, Transthyretin-Associated Familial, Reflex, Blood

Clinical Use

Use

This test is used for the diagnosis of adult individuals suspected of having transthyretin-associated familial amyloidosis, which is an autosomal dominant disorder resulting from variants in the transthyretin gene. The presence of a gene variant may lead to unstable amyloidogenic transthyretin protein, causing progressive symptoms like sensorimotor neuropathy, cardiomyopathy, and more, often culminating in cardiac or kidney failure. Through mass spectrometry, this test evaluates the transthyretin protein structure, followed by DNA sequence analysis of the TTR gene for structural changes identified.

Special Instructions

If familial amyloidosis is suspected but mass spectrometry returns a negative result, the healthcare provider may request additional full gene analysis through TTRZ / TTR Gene, Full Gene Analysis. Utilize forms like the Hematopathology/Cytogenetics Test Request (T726) or Biochemical Genetics Test Request (T798) if ordering manually.

Limitations

Mass spectrometry might not identify gene variants resulting in a protein change less than 10 atomic mass units, or frequent nondisease-causing alterations. As over 12% of the population has certain innocuous alterations, molecular testing is sometimes necessary to confirm findings. Technical assay limitations like homology and high GC content can also hinder effective evaluation of the TTR gene.

Test Details

New York Approved