NTRK1 and thyroid gland carcinoma: DNA and RNA next-generation sequencing identified a TPM3-NTRK1 fusion gene, a known oncogenic driver identified in about 8% of TRK fusion–positive thyroid cancers.15 The patient proceeded to a hypothyroid 123I thyroid scan while following a low iodine diet and with a documented low random urine iodine level (Table 1).