The severity of bone lesions and levels of haemoglobin, serum calcium, serum creatinine, C-reactive protein (CRP), serum albumin and β2-microglobulin (β2M) have been identified as independent prognostic factors for survival in patients with MM, and have been incorporated into staging systems such as the Durie-Salmon (5) and International Staging Systems (ISS) (2). Here, B2M is linked to Miyoshi myopathy.