As shown in Figure 1A, TMA-IHC analysis of bone marrow tissues derived from healthy donors and from MGUS and MM patients revealed low or undetectable XBP-1 protein expression in the plasma cells from ten healthy donors yet robust and widespread XBP-1 expression in 10/20 (50%) of MGUS and 50/70 (70%) of MM samples. This evidence concerns the gene XBP1 and Miyoshi myopathy.