Somatic, heterozygous, gain-of-function (GoF) variants in IDH1 (p.Arg132His, p.Arg132Cys, and p.Arg132Ser) and IDH2 (p.Arg172Ser) occur in the enchondromas, vascular anomalies and chondrosarcomas of approximately 80% of the individuals with OD and MS but this is not consistent even in different enchondromas isolated from the same individual [4,5]. This evidence concerns the gene IDH2 and chondrosarcoma.