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


Reviewed December 2012

What is the official name of the BRAF gene?

The official name of this gene is “B-Raf proto-oncogene, serine/threonine kinase.”

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

What is the normal function of the BRAF gene?

The BRAF gene provides instructions for making a protein that helps transmit chemical signals from outside the cell to the cell's nucleus. This protein is part of a signaling pathway known as the RAS/MAPK pathway, which helps control several important cell functions. Specifically, the RAS/MAPK pathway regulates the growth and division (proliferation) of cells, the process by which cells mature to carry out specific functions (differentiation), cell movement (migration), and the self-destruction of cells (apoptosis). Chemical signaling through this pathway is essential for normal development before birth.

The BRAF gene belongs to a class of genes known as oncogenes. When mutated, oncogenes have the potential to cause normal cells to become cancerous.

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

cardiofaciocutaneous syndrome - caused by mutations in the BRAF gene

Mutations in the BRAF gene are the most common cause of cardiofaciocutaneous syndrome. At least 45 BRAF mutations have been identified in people with this disorder. These mutations change single protein building blocks (amino acids) in the BRAF protein. Almost all of these genetic changes abnormally activate the protein, which disrupts the tightly regulated RAS/MAPK signaling pathway in cells throughout the body. The altered signaling interferes with the normal development of many organs and tissues, resulting in the characteristic features of cardiofaciocutaneous syndrome.

giant congenital melanocytic nevus - caused by mutations in the BRAF gene

At least one mutation in the BRAF gene has been found to cause giant congenital melanocytic nevus. This condition is characterized by a large, noncancerous patch of abnormally dark skin that is present from birth and an increased risk of a type of skin cell cancer called melanoma. The BRAF gene mutation that causes this condition is somatic, meaning that it occurs during a person's lifetime and is present only in certain cells. The mutation occurs during embryonic development in cells that will develop into pigment-producing skin cells (melanocytes). The mutation that causes this condition affects a single amino acid in the BRAF protein. Specifically, the mutation replaces the amino acid valine with the amino acid glutamic acid at position 600 (written as Val600Glu or V600E). This mutation leads to production of a BRAF protein that is abnormally active, which disrupts regulation of cell growth and division. The unregulated cell growth of early melanocytes leads to a large patch of darkly pigmented skin characteristic of giant congenital melanocytic nevus. Uncontrolled cell growth of melanocytes after birth contributes to the risk of developing melanoma in people with giant congenital melanocytic nevus.

multiple lentigines syndrome - caused by mutations in the BRAF gene

At least two mutations in the BRAF gene have been found to cause multiple lentigines syndrome (formerly called LEOPARD syndrome). This condition is characterized by multiple brown skin spots (lentigines), heart defects, short stature, genital abnormalities, hearing loss, and distinctive facial features. These mutations change single amino acids in the BRAF protein. One mutation replaces the amino acid threonine with the amino acid proline at position 241 in the BRAF protein (written as Thr241Pro or T241P). The other mutation replaces the amino acid leucine with the amino acid phenylalanine at position 245 in the BRAF protein (written as Leu245Phe or L245F).

The known BRAF gene changes that cause multiple lentigines syndrome are believed to abnormally activate the BRAF protein, which disrupts the regulation of the RAS/MAPK signaling pathway that controls cell functions such as growth and division. This misregulation can result in the various features of multiple lentigines syndrome.

Noonan syndrome - caused by mutations in the BRAF gene

At least six BRAF gene mutations have been found to cause Noonan syndrome. These mutations change single amino acids in the BRAF protein. The resulting protein is continuously active, rather than switching on and off in response to cell signals. This increase in protein activity disrupts the regulation of the RAS/MAPK signaling pathway, which controls cell functions such as growth and division. This misregulation can result in the heart defects, growth problems, skeletal abnormalities and other features of Noonan syndrome.

cancers - associated with the BRAF gene

Somatic mutations in the BRAF gene are common in several types of cancer. Normally, the BRAF protein is switched on and off in response to signals that control cell growth and development. Somatic mutations cause the BRAF protein to be continuously active and to transmit messages to the nucleus even in the absence of these chemical signals. The overactive protein may contribute to the growth of cancers by allowing abnormal cells to grow and divide uncontrollably.

The V600E mutation (described above) is the most common BRAF gene mutation found in human cancers. This mutation has frequently been found in an aggressive form of skin cancer called melanoma as well as in cancers of the colon and rectum, ovary, and thyroid gland. Several other somatic mutations in the BRAF gene have also been associated with cancer.

For reasons that are unclear, inherited mutations in the BRAF gene do not appear to increase the risk of cancer in people with cardiofaciocutaneous syndrome, multiple lentigines syndrome, or Noonan syndrome.

Langerhans cell histiocytosis - associated with the BRAF gene

Somatic mutations in the BRAF gene, most frequently the V600E mutation (described above), have been identified in some individuals with Langerhans cell histiocytosis. This disorder causes an abnormal accumulation of immune cells called Langerhans cells in multiple tissues and organs, which often leads to the formation of tumors called granulomas. However, Langerhans cell histiocytosis is usually not considered a form of cancer.

The BRAF gene mutations, which are found only in the abnormal Langerhans cells, cause the BRAF protein to be continuously active. The overactive protein may contribute to the development of Langerhans cell histiocytosis by allowing the Langerhans cells to grow and divide uncontrollably.

other disorders - associated with the BRAF gene

At least one somatic mutation in the BRAF gene, the V600E mutation (described above), has been identified in some people with Erdheim-Chester disease. This rare condition is characterized by the abnormal accumulation of immune system cells called histiocytes in many of the body's tissues; it is classified as a form of non-Langerhans cell histiocytosis. The disease most commonly affects the bones, causing bone thickening and pain, but the accumulation of histocytes can also cause signs and symptoms affecting the brain, eyes, lungs, liver, kidneys, and other organs.

The V600E mutation causes the BRAF protein to be continuously active, which may allow histiocytes to grow and divide uncontrollably. However, it is unclear how this mutation is related to Erdheim-Chester disease.

Where is the BRAF gene located?

Cytogenetic Location: 7q34

Molecular Location on chromosome 7: base pairs 140,715,950 to 140,924,763

The BRAF gene is located on the long (q) arm of chromosome 7 at position 34.

The BRAF gene is located on the long (q) arm of chromosome 7 at position 34.

More precisely, the BRAF gene is located from base pair 140,715,950 to base pair 140,924,763 on chromosome 7.

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

Where can I find additional information about BRAF?

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

  • 94 kDa B-raf protein
  • BRAF1
  • B-raf 1
  • B-Raf proto-oncogene serine/threonine-protein kinase
  • Murine sarcoma viral (v-raf) oncogene homolog B1
  • p94
  • RAFB1
  • v-raf murine sarcoma viral oncogene homolog B

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

What glossary definitions help with understanding BRAF?

acids ; amino acid ; apoptosis ; biomarker ; cancer ; cell ; class ; colon ; congenital ; differentiation ; embryonic ; gastrointestinal ; gene ; glutamic acid ; immune system ; inherited ; kinase ; leucine ; melanocytes ; melanoma ; mutation ; nucleus ; oncogene ; ovary ; pharmacogenomics ; phenylalanine ; pigment ; proliferation ; proline ; protein ; proto-oncogene ; RAS ; rectum ; sarcoma ; serine ; short stature ; somatic mutation ; stature ; syndrome ; threonine ; threonine kinase ; thyroid ; tumor ; valine

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


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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: December 2012
Published: March 23, 2015