Soluble BCMA levels may also play a pathophysiological role in multiple myeloma since they could inhibit the ligand (B cell activating factor, BAFF) binding to its membrane-bound BCMA to induce signaling and stimulate normal B-cell and plasma cell development, thereby resulting in reduced polyclonal antibody levels [109]. The gene discussed is TNFSF13B; the disease is AL amyloidosis.