In nearly half of MM cases, MIE include overexpression of the oncogenes CCND1, MAF and MMSET by their juxtaposition to the immunoglobulin heavy chain (IgH) enhancer, thus defining the t(11;14), t(14;16) and t(4;14) cytogenetic subgroups, respectively. The gene discussed is CCND1; the disease is Miyoshi myopathy.