Given that the ECR2 L309I mutation is absent in patients with Ollier disease (with multiple chondromas only), while Maffucci’s syndrome is characterized by the coexistence of multiple chondromas and hemangiomas, we thus hypothesized that the IDH1 R132C mutation causes multiple chondromas, while the ERC2 L309I mutation is responsible for the development of hemangiomas. The gene discussed is ERC2; the disease is chondroma.