Structural genetic abnormalities, including mutations in p53 (exons 5–8), RAS (codons 12, 13, 61), and Gsα (codons 201 and 227), and, less frequently, in receptor tyrosine kinases such as RET and NTRK1, have been found in various sporadic thyroid tumors in adults [128]; however, no p53 gene mutations have been found in thyroid cancer from the Chernobyl nuclear accident [129,130]. Here, NTRK1 is linked to thyroid cancer.