SLC5A8 and neoplasm: In summary, mutation and RNA expression analysis of the primary NTRK-rearranged tumors detected a TERT promoter mutation and a low TDS, with downregulation of the apical iodide transporter (SLC5A8) and the sodium–iodide symporter (SLC545) gene expression in the primary tumor of a patient without re-induction of RAI uptake (Fig. 8).