NTRK1 and pleomorphic xanthoastrocytoma: Because PXA and IHG may share the same fusions (PPP1CB::ALK, GOPC::ROS1, and TPM3::NTRK1) [11, 12, 15], these results reinforce the diagnostic utility of searching for a homozygous deletion of CDKN2A for the diagnosis of PXA.