MYOM2 and Miyoshi myopathy: Additionally, the presence of M protein (IgG, ҡ-type) and a plasma cell phenotype, which is indicative of the presence of clonal plasma cells (restricted expression of the ҡ-light chain), supported the diagnosis of MM.[3] However, a diagnosis of symptomatic MM also necessitates evidence of target organ damage, namely, CRAB-SLIM symptoms.