Unsupervised clustering analysis of RNAseq data from 32 canine MM samples highlighted the existence of two molecular subgroups of MM with differential expressions: one characterized by immune and microenvironment signatures, and the second by the overexpression of oncogenes (such as MDM2, CDK4, and TERT, which were characterized by the enrichment of complex chromosomal rearrangements). The gene discussed is CDK4; the disease is Miyoshi myopathy.