To clarify the pathogenesis of MM, efforts have been focused on the identification of MM oncogenes, such as NRAS, BRAF, PTEN, MITF, NEDD9, hTERT and KIT, which have led to an improved understanding of MM etiology and opened new avenues for personalized treatment [5,6,7,8,9,10]. The gene discussed is PTEN; the disease is Miyoshi myopathy.