B2M and Miyoshi myopathy: Considering the above, in this single-centre retrospective analysis, we considered the RDW in a cohort of 190 patients with newly diagnosed symptomatic MM before systematic treatment, to examine the trend of this erythrocyte index in relation to the various MM isotypes, to the International Staging System (ISS) and, especially, to the main prognostic predictors (albuminemia, beta-2 microglobulin, LDH and plasma cell infiltration in the bone marrow).