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


Reviewed May 2006

What is the official name of the SLC5A5 gene?

The official name of this gene is “solute carrier family 5 (sodium/iodide cotransporter), member 5.”

SLC5A5 is the gene's official symbol. The SLC5A5 gene is also known by other names, listed below.

What is the normal function of the SLC5A5 gene?

The SLC5A5 gene provides instructions for making a protein called sodium-iodide symporter or NIS. In certain tissues, this protein facilitates the uptake of iodide (a negatively charged version of iodine). The NIS protein is found primarily in the thyroid gland, a butterfly-shaped tissue in the lower neck. The thyroid gland produces and releases iodide-containing thyroid hormones that play an important role in regulating growth, brain development, and the rate of chemical reactions in the body (metabolism). The NIS protein supports a remarkably efficient system that ensures iodine from the diet accumulates in the thyroid gland for the production of thyroid hormones. This system depends on the NIS protein being positioned in the cell membrane, so it can transport iodide from the bloodstream into particular thyroid cells called follicular cells.

In addition to the thyroid gland, the NIS protein is found in breast tissue during milk production (lactation), ovaries, salivary glands, certain stomach cells (parietal cells), tear glands (lacrimal glands), and a part of the brain called the choroid plexus. During lactation, the NIS protein transports iodide into the milk to supply breast-fed infants with this critical component of thyroid hormones.

Does the SLC5A5 gene share characteristics with other genes?

The SLC5A5 gene belongs to a family of genes called SLC (solute carriers).

A gene family is a group of genes that share important characteristics. Classifying individual genes into families helps researchers describe how genes are related to each other. For more information, see What are gene families? ( in the Handbook.

How are changes in the SLC5A5 gene related to health conditions?

congenital hypothyroidism - caused by mutations in the SLC5A5 gene

Several SLC5A5 gene mutations have been identified in people with congenital hypothyroidism. About half of these mutations delete part of the SLC5A5 gene or disrupt protein production, resulting in an abnormally small, nonfunctional protein. The remaining mutations change one of the building blocks (amino acids) used to make the NIS protein. Some amino acid substitutions prevent the NIS protein from being positioned in the cell membrane, disabling iodide transport. Other amino acid substitutions do not affect the membrane location of the NIS protein but change the protein's 3-dimensional shape, which impairs its function.

SLC5A5 gene mutations reduce or prevent iodide transport. As a result, the thyroid gland cannot accumulate iodide efficiently, which decreases the production of thyroid hormones. The signs and symptoms of congenital hypothyroidism range from mild to severe depending on the level of hormone production. In many cases, the thyroid gland is enlarged (goiter) in an attempt to compensate for reduced hormone production.

Where is the SLC5A5 gene located?

Cytogenetic Location: 19p13.11

Molecular Location on chromosome 19: base pairs 17,871,410 to 17,895,173

The SLC5A5 gene is located on the short (p) arm of chromosome 19 at position 13.11.

The SLC5A5 gene is located on the short (p) arm of chromosome 19 at position 13.11.

More precisely, the SLC5A5 gene is located from base pair 17,871,410 to base pair 17,895,173 on chromosome 19.

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

Where can I find additional information about SLC5A5?

You and your healthcare professional may find the following resources about SLC5A5 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 SLC5A5 gene or gene products?

  • NIS
  • sodium-iodide symporter

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

What glossary definitions help with understanding SLC5A5?

acids ; amino acid ; carrier ; cell ; cell membrane ; choroid ; choroid plexus ; congenital ; gene ; goiter ; hormone ; hypothyroidism ; iodine ; lactation ; metabolism ; protein ; sodium ; solute ; stomach ; thyroid ; thyroid hormones ; tissue

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


  • De La Vieja A, Dohan O, Levy O, Carrasco N. Molecular analysis of the sodium/iodide symporter: impact on thyroid and extrathyroid pathophysiology. Physiol Rev. 2000 Jul;80(3):1083-105. Review. (
  • Dohán O, Carrasco N. Advances in Na(+)/I(-) symporter (NIS) research in the thyroid and beyond. Mol Cell Endocrinol. 2003 Dec 31;213(1):59-70. Review. (
  • Dohán O, De la Vieja A, Paroder V, Riedel C, Artani M, Reed M, Ginter CS, Carrasco N. The sodium/iodide Symporter (NIS): characterization, regulation, and medical significance. Endocr Rev. 2003 Feb;24(1):48-77. Review. (
  • NCBI Gene (
  • Pohlenz J, Refetoff S. Mutations in the sodium/iodide symporter (NIS) gene as a cause for iodide transport defects and congenital hypothyroidism. Biochimie. 1999 May;81(5):469-76. Review. (
  • Spitzweg C, Morris JC. The sodium iodide symporter: its pathophysiological and therapeutic implications. Clin Endocrinol (Oxf). 2002 Nov;57(5):559-74. Review. (
  • Szinnai G, Kosugi S, Derrien C, Lucidarme N, David V, Czernichow P, Polak M. Extending the clinical heterogeneity of iodide transport defect (ITD): a novel mutation R124H of the sodium/iodide symporter gene and review of genotype-phenotype correlations in ITD. J Clin Endocrinol Metab. 2006 Apr;91(4):1199-204. Epub 2006 Jan 17. (


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: May 2006
Published: March 23, 2015