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Reviewed July 2014

What is the official name of the KLKB1 gene?

The official name of this gene is “kallikrein B1.”

KLKB1 is the gene's official symbol. The KLKB1 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 KLKB1 gene?

The KLKB1 gene provides instructions for making a protein called prekallikrein. Prekallikrein is produced in the liver and circulates in the blood. A molecule called factor XII converts prekallikrein to another protein called plasma kallikrein, and plasma kallikrein helps turn on (activate) more factor XII. Plasma kallikrein and factor XII are involved in the early stages of blood clotting as part of a process called the intrinsic coagulation pathway (also called the contact activation pathway). Blood clots protect the body after an injury by sealing off damaged blood vessels and preventing further blood loss.

The interaction between plasma kallikrein and factor XII also initiates a series of chemical reactions resulting in the release of a protein called bradykinin. Bradykinin promotes inflammation by increasing the permeability of blood vessel walls, allowing more fluids to leak into body tissues. This leakage causes the swelling that accompanies inflammation.

Does the KLKB1 gene share characteristics with other genes?

The KLKB1 gene belongs to a family of genes called KLK (kallikreins).

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 KLKB1 gene related to health conditions?

prekallikrein deficiency - caused by mutations in the KLKB1 gene

At least nine KLKB1 gene mutations have been identified in people with a blood condition called prekallikrein deficiency, which does not generally cause any health problems. The condition is usually discovered when blood tests are done for other reasons.

The KLKB1 gene mutations that cause this condition reduce or eliminate functional plasma kallikrein in the blood of affected individuals and likely impair the intrinsic coagulation pathway. Researchers suggest that this lack (deficiency) of functional plasma kallikrein protein does not generally cause any symptoms because another process called the extrinsic coagulation pathway (also known as the tissue factor pathway) can compensate for the impaired intrinsic coagulation pathway. Either pathway can activate proteins that are needed later in the clotting process.

Where is the KLKB1 gene located?

Cytogenetic Location: 4q35

Molecular Location on chromosome 4: base pairs 186,210,753 to 186,258,474

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

The KLKB1 gene is located on the long (q) arm of chromosome 4 at position 35.

The KLKB1 gene is located on the long (q) arm of chromosome 4 at position 35.

More precisely, the KLKB1 gene is located from base pair 186,210,753 to base pair 186,258,474 on chromosome 4.

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

Where can I find additional information about KLKB1?

You and your healthcare professional may find the following resources about KLKB1 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 KLKB1 gene or gene products?

  • Fletcher factor
  • kallikrein B, plasma (Fletcher factor) 1
  • kininogenin
  • plasma kallikrein
  • plasma kallikrein preproprotein
  • plasma prekallikrein
  • PPK

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 KLKB1?

blood clotting ; bradykinin ; clotting ; coagulation ; deficiency ; gene ; inflammation ; injury ; molecule ; permeability ; plasma ; protein ; 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: July 2014
Published: February 8, 2016