In summary, based on WES and WGS data, we conclude that OD and MS are cancer susceptibility syndromes characterized by cartilage and vascular abnormalities and mainly caused by pathogenic variants in HIF1A, VHL, IDH1, and, possibly, other genes related with the HIF-1 pathway such as IDH2, KDM4C, or CDKN2A. The gene discussed is IDH2; the disease is myeloid sarcoma.