KMT2C and osteosarcoma: In our previous study of Whole Exome Sequencing (WES) analysis [11], we confirmed that the osteosarcoma karyotype is complex; indeed, we did not find a genetic variation common to all high-grade osteosarcoma diagnostic biopsies analyzed, but we found that the KMT2C gene, a key component of histone H3 lysine 4 methyltransferase complexes [12], showed the highest number of variations in most of the samples being analyzed.