Cardiac AL Amyloidosis – the role of serum Immunoglobulin Free Llight Chain assay (sFLC) in diagnosis and prognostic classification

Abstract

Systemic immunoglobulin light chain amyloidosis (AL amyloidosis) is a cancer in which the amyloid fibrils are formed from amyloid immunoglobulin free light chain (FLC) κ or λ, produced by a plasma cell clone. The created protein adopts the structure of β-sheets, and depositing in tissues and organs leads to their function impairment. Cardiomyopathies are the main cause of death in patients with amyloidosis. Diagnosis of cardiac involvement is too late owing to nonspecific symptoms and no early characteristic changes observed in imaging studies. The currently valid prognostic classification of AL amyloidosis created by Kumar et al. is based on biochemical parameters evaluating function and the degree of myocardial damage: concentration of troponin (Tn) and N-terminal fragment of B-type natriuretic peptide (NT-proBNP) and the value of dFLC, representing the difference between the concentration of serum FLC (sFLC) involved and not involved in the neoplastic process. There are reports indicating that myocardial dysfunction in AL amyloidosis stems not only from the amyloid deposit in the organ, but it is also the result of the cardiotoxicity amyloid precursor – FLC, circulating in the blood.