NTRK1 and pleomorphic xanthoastrocytoma: In the same study, a case of PA bore a fusion of breakpoint cluster region (BCR) and NTRK2 genes (BCR-NTRK2), while a patient with pleomorphic xanthoastrocytoma (PXA) harbored the tropomyosin 3 (TPM3)-NTRK1 fusion.