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Reviewed August 2012

What is the official name of the KL gene?

The official name of this gene is “klotho.”

KL is the gene's official symbol. The KL 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 KL gene?

The KL gene provides instructions for making the protein alpha-klotho, which is found primarily in kidney cells. This protein plays a major role in regulating the phosphate levels within the body (phosphate homeostasis). Among its many functions, phosphate plays a critical role in the formation and growth of bones in childhood and helps maintain bone strength in adults. Phosphate levels are controlled in large part by the kidneys. The kidneys normally rid the body of excess phosphate by excreting it in urine, and they reabsorb this mineral into the bloodstream when more is needed.

Alpha-klotho attaches (binds) to and turns on (activates) a protein called FGF receptor 1 that spans the membrane of many types of cells, including kidney cells. Once the receptor is active, another protein called fibroblast growth factor 23 can also bind to it. Binding of fibroblast growth factor 23 to its receptor stimulates signaling that stops phosphate reabsorption into the bloodstream.

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

hyperphosphatemic familial tumoral calcinosis - caused by mutations in the KL gene

At least one mutation in the KL gene has been found to cause hyperphosphatemic familial tumoral calcinosis (HFTC), a condition characterized by an increase in the levels of phosphate in the blood (hyperphosphatemia) and abnormal deposits of phosphate and calcium (calcinosis) in the body's tissues. The KL gene mutation that causes HFTC replaces the protein building block (amino acid) histidine with the amino acid arginine at position 193 in the protein sequence (written as His193Arg or H193R). This mutation results in a shortage of functional alpha-klotho. As a result, FGF receptor 1 is not activated, making it unavailable for fibroblast growth factor 23 binding. The fibroblast growth factor 23 protein is normal, but it cannot bind to its receptor and cannot send out signals to stop phosphate reabsorption. As a result, too much phosphate is reabsorbed into the bloodstream, leading to hyperphosphatemia and subsequent calcinosis.

Where is the KL gene located?

Cytogenetic Location: 13q12

Molecular Location on chromosome 13: base pairs 33,590,570 to 33,640,281

The KL gene is located on the long (q) arm of chromosome 13 at position 12.

The KL gene is located on the long (q) arm of chromosome 13 at position 12.

More precisely, the KL gene is located from base pair 33,590,570 to base pair 33,640,281 on chromosome 13.

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

Where can I find additional information about KL?

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

  • alpha-klotho
  • klotho precursor

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 KL?

acids ; amino acid ; calcinosis ; calcium ; cell ; familial ; fibroblast ; gene ; growth factor ; homeostasis ; kidney ; mineral ; mutation ; phosphate ; protein ; protein sequence ; receptor ; tissue

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

See also Understanding Medical Terminology.

References (6 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: August 2012
Published: February 11, 2013