In a preliminary assessment of calretinin as a possible tumor marker its concentrations were measured in 1:2 to 1:4 diluted sera from healthy subjects (n = 65) and from patients with diagnosed MM (n = 27) as well as in 1:5 diluted EDTA plasmas (32 healthy subjects and 15 patients with MM). This evidence concerns the gene CALB2 and Miyoshi myopathy.