IDH1 and brain neoplasm: The seven individuals who were not molecular singletons include three with primary brain tumors and a solitary molecular lesion (IDH1 R132H mutation), and two sets of tumor molecular twins that had two alterations in common—however, these alterations did not segregate by histology (lung adenocarcinoma-appendiceal cancer (KRAS G12D and GNAS R201C), and lung adenocarcinoma-liposarcoma (CDK4 and MDM2 amplification pairs)).