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Genetics Home Reference: your guide to understanding genetic conditions     A service of the U.S. National Library of Medicine®


Reviewed September 2015

What is the official name of the TPO gene?

The official name of this gene is “thyroid peroxidase.”

TPO is the gene's official symbol. The TPO gene is also known by other names, listed below.

What is the normal function of the TPO gene?

The TPO gene provides instructions for making an enzyme called thyroid peroxidase. This enzyme plays a central role in the function of the thyroid gland, a butterfly-shaped tissue in the lower neck. Thyroid peroxidase assists the chemical reaction that adds iodine to a protein called thyroglobulin, a critical step in generating thyroid hormones. Thyroid hormones play an important role in regulating growth, brain development, and the rate of chemical reactions in the body (metabolism).

To function properly, thyroid peroxidase must be located in the cell membrane of certain thyroid cells, called follicular cells. Thyroid peroxidase has several different versions (isoforms), which vary by size and location within the cell. Some versions do not function because they are not located in the cell membrane.

How are changes in the TPO gene related to health conditions?

congenital hypothyroidism - caused by mutations in the TPO gene

TPO gene mutations can cause congenital hypothyroidism, a condition characterized by abnormally low levels of thyroid hormones starting from birth. The TPO gene mutations involved in this condition delete, add, or change DNA building blocks (base pairs) in the TPO gene. Some mutations lead to an abnormally small thyroid peroxidase enzyme that breaks apart before it can be inserted into the cell membrane. Other mutations change the enzyme's 3-dimensional shape, preventing it from functioning properly within the cell membrane. Without functional thyroid peroxidase, iodine taken up by the thyroid gland is not added to thyroglobulin. As a result, the production of thyroid hormones is absent or reduced, leading to the features of congenital hypothyroidism. In most affected individuals, the thyroid gland is enlarged (goiter) in an attempt to compensate for reduced hormone production. Because cases caused by TPO gene mutations result from a disruption of thyroid hormone synthesis, they are classified as thyroid dyshormonogenesis.

Where is the TPO gene located?

Cytogenetic Location: 2p25

Molecular Location on chromosome 2: base pairs 1,413,460 to 1,542,726

The TPO gene is located on the short (p) arm of chromosome 2 at position 25.

The TPO gene is located on the short (p) arm of chromosome 2 at position 25.

More precisely, the TPO gene is located from base pair 1,413,460 to base pair 1,542,726 on chromosome 2.

See How do geneticists indicate the location of a gene? ( in the Handbook.

Where can I find additional information about TPO?

You and your healthcare professional may find the following resources about TPO helpful.

You may also be interested in these resources, which are designed for genetics professionals and researchers.

What other names do people use for the TPO gene or gene products?

  • MSA
  • thyroid microsomal antigen
  • thyroperoxidase
  • TPX

See How are genetic conditions and genes named? ( in the Handbook.

What glossary definitions help with understanding TPO?

autoimmune ; cell ; cell membrane ; congenital ; DNA ; enzyme ; gene ; goiter ; hormone ; hypothyroidism ; iodine ; isoforms ; metabolism ; protein ; synthesis ; thyroglobulin ; thyroid ; thyroid hormones ; tissue

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.


  • Bakker B, Bikker H, Vulsma T, de Randamie JS, Wiedijk BM, De Vijlder JJ. Two decades of screening for congenital hypothyroidism in The Netherlands: TPO gene mutations in total iodide organification defects (an update). J Clin Endocrinol Metab. 2000 Oct;85(10):3708-12. (
  • Cangul H, Aycan Z, Olivera-Nappa A, Saglam H, Schoenmakers NA, Boelaert K, Cetinkaya S, Tarim O, Bober E, Darendeliler F, Bas V, Demir K, Aydin BK, Kendall M, Cole T, Högler W, Chatterjee VK, Barrett TG, Maher ER. Thyroid dyshormonogenesis is mainly caused by TPO mutations in consanguineous community. Clin Endocrinol (Oxf). 2013 Aug;79(2):275-81. doi: 10.1111/cen.12127. Epub 2013 May 6. (
  • Chardès T, Chapal N, Bresson D, Bès C, Giudicelli V, Lefranc MP, Péraldi-Roux S. The human anti-thyroid peroxidase autoantibody repertoire in Graves' and Hashimoto's autoimmune thyroid diseases. Immunogenetics. 2002 Jun;54(3):141-57. Epub 2002 May 3. Review. (
  • Kotani T, Umeki K, Kawano J, Suganuma T, Hishinuma A, Ieiri T, Harada S. Partial iodide organification defect caused by a novel mutation of the thyroid peroxidase gene in three siblings. Clin Endocrinol (Oxf). 2003 Aug;59(2):198-206. (
  • Lee CC, Harun F, Jalaludin MY, Lim CY, Ng KL, Mat Junit S. Functional analyses of C.2268dup in thyroid peroxidase gene associated with goitrous congenital hypothyroidism. Biomed Res Int. 2014;2014:370538. doi: 10.1155/2014/370538. Epub 2014 Mar 17. (
  • Nascimento AC, Guedes DR, Santos CS, Knobel M, Rubio IG, Medeiros-Neto G. Thyroperoxidase gene mutations in congenital goitrous hypothyroidism with total and partial iodide organification defect. Thyroid. 2003 Dec;13(12):1145-51. (
  • NCBI Gene (
  • Rivolta CM, Esperante SA, Gruñeiro-Papendieck L, Chiesa A, Moya CM, Domené S, Varela V, Targovnik HM. Five novel inactivating mutations in the thyroid peroxidase gene responsible for congenital goiter and iodide organification defect. Hum Mutat. 2003 Sep;22(3):259. (


The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? ( in the Handbook.

Reviewed: September 2015
Published: October 12, 2015