B cell maturation antigen (BCMA), a member of the TNF receptor superfamily, is preferentially expressed by mature B lymphocytes but is rarely expressed in hematopoietic stem cells.390 The ligands for BCMA, such as B-cell activating factor and a proliferation-inducing ligand (APRIL), can activate the NF-κB pathway.387,391,392 Nevertheless, the overexpression of BCMA and increased activation correlate with the progression of MM. The gene discussed is NFKB1; the disease is Miyoshi myopathy.