We found that in mice engrafted with MM cell lines U-266 (Fig. 4d) and RPMI-8226 (Fig. 4e), treatment with CD229 CAR T cells resulted in the loss of luminescence signal in 5/5 and 4/5 animals, respectively, a significant reduction in MM-related serum light-chain levels (Supplementary Fig. 4D), and significantly prolonged survival. The gene discussed is TNFSF14; the disease is Miyoshi myopathy.