CD19 and Miyoshi myopathy: Regarding mature B-cells, significantly reduced percentages of TBC/NBC and nPC were also found in BM of MM patients studied at diagnosis vs. age-matched HD with median percentages of TBC/NBC at 0.4% vs. 1.1% (p = 0.01), of CD19+ nPC at 0.03% vs. 0.2% (p ≤ 0.001) and of CD19− nPC at 0.006% vs. 0.1% (p ≤ 0.001), respectively (Figure 2).