Nevertheless, since the CD38 marker may fade or weaken compared to the CD138 marker in PCs after chemotherapy (208) and BCMA- and/or CD38-negative relapses have also been observed (209–211), the need for complementary treatment strategies must be carefully considered and strongly recommended, highlighting CD138 as a compelling candidate for further development of anti-MM approaches. Here, SDC1 is linked to Miyoshi myopathy.