With clinical suspicion of cardiac amyloidosis, the first step is to screen for monoclonal gammopathy with SPEP, serum and urine IFE, and a free light chain assay; if evidence of monoclonal proteins is detected, the next step is a tissue biopsy with Congo red staining and possibly LC/MS to identify the type of amyloidosis; if monoclonal gammopathy is not found, then nuclear scintigraphy can be performed if available with a positive result being diagnostic for ATTR amyloidosis. The gene discussed is TNFSF14; the disease is amyloidosis.