A cohort study of survivors of the Chernobyl nuclear accident documents a marked rise in childhood thyroid carcinoma decades after exposure to radioactive iodine fallout. Molecular analysis of these radiation-induced tumors most commonly demonstrates:
- A Chromosomal rearrangements generating RET/PTC fusion genes ✓
- B Point mutations in BRAF V600E
- C RAS codon 61 mutations
- D Germline RET proto-oncogene missense mutations
Correct answer: A. Chromosomal rearrangements generating RET/PTC fusion genes
Explanation
Ionizing radiation induces double-strand DNA breaks, and misrepair generates chromosomal inversions and translocations that fuse the tyrosine kinase domain of RET to heterologous promoters, producing constitutively active RET/PTC fusion transcripts. Such rearrangements dominate radiation-associated papillary thyroid carcinoma, including the post-Chernobyl epidemic. BRAF V600E predominates in sporadic papillary carcinoma without radiation history, RAS mutations mark follicular lesions, and germline RET mutations cause familial medullary thyroid carcinoma in MEN2.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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