What is the role of the DNA tests in the evaluation of a solitary thyroid nodule?

Updated: Aug 19, 2020
  • Author: Daniel J Kelley, MD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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DNA testing has proven to be an effective method for the diagnosis of MEN 2a and 2b syndromes. ret proto-oncogene in the paracentromeric region of the short arm of chromosome 10 is the site of mutation in 90% patients with familial medullary thyroid carcinoma and medullary thyroid carcinoma associated with MEN 2a and 2b. Patients with medullary thyroid carcinoma should undergo direct DNA analysis to identify possible germline mutations in the ret proto-oncogene. All family members should undergo similar testing if a ret mutation is identified. Family members with the ret mutation should undergo genetic counseling and be informed about prophylactic thyroidectomy.

Advances in molecular genetic testing hold the greatest promise for the development of a highly accurate serum marker to distinguish benign from malignant thyroid nodules. It is now possible to detect thyroid cancer cells in peripheral blood samples by measuring the mRNA of thyroid-specific genes, such as the mRNA of thyroglobulin and the thyrotropin receptor. In addition, microRNAs, which are small endogenous noncoding RNAs involved with the regulation of gene expression, can be detected in serum of patient's with thyroid cancer. Additional research in this area may ultimately develop what is the holy grail of diagnostic tests for the evaluation of solitary thyroid nodules.

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