We studied 198 papillary thyroid carcinomas (PTCs), 34 follicular thyroid carcinomas (FTCs), 40 Hürthle cell carcinomas (HCCs), 14 poorly differentiated/anaplastic thyroid carcinomas (PDTC/ATC), and 15 medullary thyroid carcinomas (MTCs) for mutations in an −424 bp to +64 bp region of TERT. The luciferase reporter assay was used to functionally characterize the identified alterations. This evidence concerns the gene TERT and medullary thyroid gland carcinoma.