The study by Sandberg et al. indicated that loss of heterozygosity (LOH) in TP53 may contribute to the transformation of pre-existing low-grade conventional chondrosarcoma into a highly malignant dedifferentiated tumour and, contrary to IDH mutations, is considered to be a late event in the development of DDCS [135,136]. The gene discussed is IDH1; the disease is chondrosarcoma.