PTH1R and Ollier disease: Several hereditary diseases are characterized by the development of cartilaginous tumors, including hereditary multiple exostoses, metachondromatosis, and enchondromatosis, which are caused by mutations in genes such as exostosin 1 and 2, tyrosine protein phosphatase non-receptor type 11, parathyroid hormone receptor 1, and isocitrate dehydrogenase 1 and 2. The proteins encoded by these genes are directly or indirectly linked to fibroblast growth factor (FGF) signaling.