Rearrangement of the RET tyrosine-kinase receptor with different genes, especially RET/PTC1 and PTC3 generated by the fusion of RET to the H4 or RFG genes, respectively, is frequently found in thyroid papillary carcinoma, particularly in childhood radiation-induced thyroid cancers (Bongarzone et al, 1994; Santoro et al, 1994; Nikiforov et al, 1997; Jhiang, 2000). The gene discussed is NTRK1; the disease is differentiated thyroid carcinoma.