IDH1 and neoplasm: This review will focus on a group of bone tumours that share mutations in genes involved in epigenetic regulation: H3 histone family member 3A and 3B (H3F3A and H3F3B) mutations in giant cell tumour of bone and chondroblastoma, respectively, and isocitrate dehydrogenase 1 and 2 (IDH1 and IDH2) mutations in central cartilaginous tumours.