Light-chain (AL) amyloidosis (ALA) is a rare but fatal monoclonal gammopathy (MG) causing organ and tissue damage resulting from the deposition of misfolded immunoglobulin free light chains in the form of amyloid fibrils.1 In some cases, ALA coexists with multiple myeloma (MM) (ALA+MM), which is the second most common blood cancer and is caused by the proliferation of clonal plasma cells (PC).2 Due to insufficient knowledge of ALA and ALA+MM biology, therapeutic options have mirrored treatment regimens of MM, which focus on the elimination of clonal PC.3,4 We investigated the mutation and gene expression profiles in clonal aberrant PC (aPC) in order to better understand ALA and ALA+MM etiology and to clarify the molecular differences between individual MG diagnoses.