For instance, SPEP, serum and urine IFE, and a free light chain assay are used to search for evidence of monoclonal proteins; TTR gene sequencing can identify a TTR gene mutation, and Tc-99m PYP and Tc-99m 3,3-diphosphono-1,2-propanodicarboxylic acid (DPD) scans can assist in diagnosing ATTR cardiac amyloidosis. Here, TTR is linked to cardiac amyloidosis.