Skip Navigation
Genetics Home Reference: your guide to understanding genetic conditions About   Site Map   Contact Us
Home A service of the U.S. National Library of Medicine®
Printer-friendly version


Reviewed September 2015

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.

Read more about gene names and symbols on the About page.

What is the normal function of the SLC5A5 gene?

The SLC5A5 gene provides instructions for making a protein called sodium (Na)-iodide symporter or NIS. This protein transports iodide, a negatively charged version of iodine, into cells of certain tissues. 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 an 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, a condition characterized by abnormally low levels of thyroid hormones starting from birth. 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 associated with these gene mutations range from mild to severe depending on the level of hormone production remaining. In many cases, the thyroid gland is enlarged (goiter) in an attempt to compensate for reduced hormone production. Because cases caused by SLC5A5 gene mutations are due to a disruption of thyroid hormone synthesis, they are classified as thyroid dyshormonogenesis.

Where is the SLC5A5 gene located?

Cytogenetic Location: 19p13.11

Molecular Location on chromosome 19: base pairs 17,871,411 to 17,895,174

(Homo sapiens Annotation Release 107, GRCh38.p2) (NCBIThis link leads to a site outside Genetics Home Reference.)

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 17,871,411 to base pair 17,895,174 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

Where can I find general information about genes?

The Handbook provides basic information about genetics in clear language.

These links provide additional genetics resources that may be useful.

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 ; Na ; protein ; sodium ; solute ; stomach ; synthesis ; thyroid ; thyroid hormones ; tissue

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

See also Understanding Medical Terminology.

References (10 links)


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: February 1, 2016