Compared with 12% of PTEN loss in CM where deletions and mutations both account for the changes (17, 79), PTEN is deeply deleted in merely 6.0% of MM cases and has hardly any mutations (16) Furthermore, there is rare co-occurrence of deleted PTEN and amplified KIT that possibly implies that loss of PTEN or gain of KIT are redundant for the activation of the PI3K pathway in MM. Here, PTEN is linked to Miyoshi myopathy.