In both PDX lines that were successfully propagated, treatment with sBCMA-Fc led to significant reduction in tumor expansion, decreased IgGκ signal, and prolonged overall survival, which demonstrates the ligand dependence of BCMA signaling in human MM (Fig. 3, H and I; and Fig. S4, B and C). The gene discussed is TNFRSF17; the disease is Miyoshi myopathy.