TNFSF13B and Miyoshi myopathy: MM patients have a three to fivefold increase of circulating BAFF when compared with healthy controls and BAFF serum levels correlate positively with disease stage according to the International Staging System.10, 40, 44, 61, 62, 63, 64, 65, 66, 67 Furthermore, BAFF serum levels correlate positively with a diverse spectrum of established progression markers in MM including several ILs (IL-6, -10 and -15), lactic dehydrogenase, C-reactive protein and beta-2-microglobulin.