Only two (8.0%) out of 25 MM patients with normal serum β2-microglobulin levels in the peripheral blood had positive expression of c-maf, while 37 (35.9%) out of 103 MM patients with significantly high serum β2-microglobulin levels had positive expression of c-maf (χ2 = 7.403, p = 0.007). The gene discussed is HLA-G; the disease is Miyoshi myopathy.