PSMB9 and Miyoshi myopathy: Differences between MGUS and MM patients were also seen regarding the extent of DNA methylation in plasma cells: of the six proteasome subunit genes analyzed, lower methylation levels were observed for Z (P = 0.0082), LMP2 (P = 0.0003), LMP7 (P =  < 0.0001) and LMP10 (P =  < 0.0001) in MGUS than MM, although the data dispersion tended to be wide (Fig. 7E).