When PTEN mRNA levels were measured to verify whether PTEN gene hypermethylation could determine loss of PTEN expression, results showed that the expression levels in MM samples differed significantly from those of non-neoplastic tissues (mean value of -0.72 ± 14 versus 0.016 ± 0.30, respectively; P <0.001) and MGUS (-0.72 ± 1.4 versus 0.14 ± 0.32, respectively; P = 0.0013). This evidence concerns the gene PTEN and Miyoshi myopathy.