A literature search by using the terms including “Thyroid Neoplasm” OR "Thyroid Carcinoma" OR "Thyroid Cancer" AND "DNA Methylations” OR “hypermethylation" OR "CpG Island" AND “sodium iodide symporter” OR "SLC5A5" was conducted in PubMed/MEDLINE, Web of Science, and Scopus databases. The gene discussed is SLC5A5; the disease is thyroid cancer.