Moreover, the majority (93.3%) of Vk*MYC MM tumors, like human MM, have undergone class switch recombination to express IgG or IgA; and out of the five cases expressing IgM, four have less than 2% somatic hypermutation at the immunoglobulin loci and lack reversion of the transgenic stop codon, suggesting a germinal center independent tumor origin, or an early germinal center exit, as recently reported in MM that develops in various different crosses with Ikk2ca activated by IgG1-CRE30,31. The gene discussed is CD79A; the disease is Miyoshi myopathy.