NTRK1 and Nijmegen breakage syndrome: These data extend earlier findings of NTRK1/TrkA exons 1–8-restricted alternative TrkA splicing in NBs, MCPyV positive Merkel cell carcinomas, and cutaneous malignant melanomas [25,26,27,28] and indicate that NTRK1/TrkA exons 2 through 7 are more prone to alternative splicing.