Levels of β2-microglobulin, the most important and reliable prognostic factor in MM, were correlated with MAGE-C1/CT7 (r = 0.21), MAGE-A3 (r = 0.30), MAGE-C2/CT10 (r = 0.25) and SSX-2 (r = 0.20) in 178 samples (all p < 0.01). The gene discussed is MAGEC1; the disease is Miyoshi myopathy.