NTRK1 re-arrangement in papillary thyroid carcinomas of children after theChernobyl reactor accident

The prevalence of NTRK1 re-arrangement was determined in papillary thyroid carcinomas (PTCs) of children from Belarus who had been exposed to radioact ive iodine after the Chernobyl reactor accident; 81 tumors were included, a ll of which were devoid of RET re-arrangement as analyzed in a current stud y on genomic alterations in PTC. Oncogenic fusion of the NTRK1 tyrosine kin ase domain with the aminoterminal part of the tropomyosin gene (TPM3/NTRK1, trk) was observed in 5 tumors. A single tumor exhibited a TPR/NTRK1 fusion (TRK-T2). Reciprocal NTRK1/TPM3 transcripts were found in 4 of 5 tumors wi th TPM3/NTRK1 re-arrangement, indicating an intra-chromosomal balanced reci procal inversion. No phenotypic differences from other post-Chernobyl child hood PTCs were detected. As compared with the high prevalence of RET re-arr angements reported for thyroid carcinomas of children after the Chernobyl r eactor accident, NTRK1 re-arrangements appear rare. Our results confirm tha t activation of receptor tyrosine kinase genes plays the predominant role i n post-Chernobyl childhood thyroid carcinogenesis. Int. J. Cancer 80:842-84 7, 1999. (C) 1999 Wiley-Liss, Inc.