demonstrated that monoclonal PCs in systemic AL amyloidosis can be identified by their aberrant phenotype (CD38+, CD56+, and CD19−) 24, we demonstrate for the first time that light chain restriction and back‐gating of CD45‐negative, CD19‐negative, and/or CD56‐positive PCs into the κ/λ gate successfully detects the aberrant PC clone. This evidence concerns the gene CD19 and AL amyloidosis.