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    Topic review

    BRAF

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    Submitted by: Vicky Zhou
    (This entry belongs to Entry Collection "MedlinePlus ")

    Definition

    B-Raf proto-oncogene, serine/threonine kinase

    1. Normal Function

    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 controls 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.

    2. Health Conditions Related to Genetic Changes

    2.1. Cardiofaciocutaneous Syndrome

    Mutations in the BRAF gene are the most common cause of cardiofaciocutaneous syndrome. This condition affects many parts of the body, particularly the heart (cardio-), facial features (facio-), and the skin and hair (cutaneous). At least 49 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.

    2.2. Erdheim-Chester Disease

    At least one mutation in the BRAF gene has been identified in some people with Erdheim-Chester disease. This rare condition is characterized by the abnormal production and accumulation of immune system cells called histiocytes in many of the body's tissues. The disease most commonly affects the bones, causing bone thickening and pain, but the accumulation of histiocytes can also cause signs and symptoms affecting the brain, eyes, lungs, liver, kidneys, and other organs.

    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 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 proliferation and may allow histiocytes to grow and divide uncontrollably, leading to the abnormal accumulation of histiocytes that occurs in Erdheim-Chester disease.

    2.3. Giant congenital Melanocytic Nevus

    The V600E mutation (described above) in the BRAF gene has also 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 (described below). In giant congenital melanocytic nevus, a somatic V600E mutation occurs during embryonic development in cells that will develop into pigment-producing skin cells (melanocytes). This mutation leads to production of a BRAF protein that is abnormally active, which disrupts regulation of cell proliferation. The unregulated cell proliferation of early melanocytes leads to a large patch of darkly pigmented skin characteristic of giant congenital melanocytic nevus. Additional gene mutations in cells within the nevus after birth can lead to melanoma in people with giant congenital melanocytic nevus.

    2.4. Noonan Syndrome

    Noonan syndrome

    2.5. Noonan Syndrome with Multiple Lentigines

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

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

    2.6. Cholangiocarcinoma

    Cholangiocarcinoma

    2.7. Gastrointestinal Stromal Tumor

    Gastrointestinal stromal tumor

    2.8. Langerhans Cell Histiocytosis

    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 certain immune cells called Langerhans cells in multiple tissues and organs, which often leads to the formation of tumors called granulomas. Many researchers consider Langerhans cell histiocytosis to be a form of cancer, but this classification is controversial.

    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.

    In some other forms of histiocytosis such as Erdheim-Chester disease (described above), the histiocytes do not include Langerhans cells; a disorder of that type is classified as a non-Langerhans cell histiocytosis. It is not clear why the V600E mutation can cause different forms of histiocytosis.

    2.9. Lung Cancer

    Lung cancer

    2.10. Melanoma

    The V600E mutation (described above) in the BRAF gene has also been found in about half of noninherited (sporadic) cases of melanoma. Melanoma is a type of skin cancer that begins in pigment-producing cells called melanocytes. In this cancer, a somatic V600E mutation occurs during a person's lifetime, likely caused by ultraviolet (UV) radiation from the sun or other environmental risk factors. This mutation often leads only to the formation of a noncancerous mole. At least one additional mutation is necessary for the development of melanoma.

    2.11. Multiple Myeloma

    Multiple myeloma

    2.12. Cancers

    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 without external signals.

    The V600E mutation (described above) is the most common BRAF gene mutation found in human cancers. This mutation has frequently been found 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.

    3. Other Names for This Gene

    • 94 kDa B-raf protein
    • B-raf 1
    • B-Raf proto-oncogene serine/threonine-protein kinase
    • BRAF1
    • BRAF1_HUMAN
    • Murine sarcoma viral (v-raf) oncogene homolog B1
    • p94
    • RAFB1
    • v-raf murine sarcoma viral oncogene homolog B

    The entry is from https://medlineplus.gov/genetics/gene/braf

    References

    1. Allen CE, Parsons DW. Biological and clinical significance of somaticmutations in Langerhans cell histiocytosis and related histiocytic neoplasticdisorders. Hematology Am Soc Hematol Educ Program. 2015;2015:559-64. doi:10.1182/asheducation-2015.1.559. Review.
    2. Aoki Y, Niihori T, Narumi Y, Kure S, Matsubara Y. The RAS/MAPK syndromes:novel roles of the RAS pathway in human genetic disorders. Hum Mutat. 2008Aug;29(8):992-1006. doi: 10.1002/humu.20748. Review.
    3. Badalian-Very G, Vergilio JA, Degar BA, MacConaill LE, Brandner B, CalicchioML, Kuo FC, Ligon AH, Stevenson KE, Kehoe SM, Garraway LA, Hahn WC, Meyerson M,Fleming MD, Rollins BJ. Recurrent BRAF mutations in Langerhans cellhistiocytosis. Blood. 2010 Sep 16;116(11):1919-23. doi:10.1182/blood-2010-04-279083. Epub 2010 Jun 2.
    4. Bosco J, Allende A, Varikatt W, Lee R, Stewart GJ. Does the BRAF(V600E)mutation herald a new treatment era for Erdheim-Chester disease? A case-basedreview of a rare and difficult to diagnose disorder. Intern Med J. 2015Mar;45(3):348-51. doi: 10.1111/imj.12685. Review.
    5. Campochiaro C, Tomelleri A, Cavalli G, Berti A, Dagna L. Erdheim-Chesterdisease. Eur J Intern Med. 2015 May;26(4):223-9. doi: 10.1016/j.ejim.2015.03.004.Epub 2015 Apr 10. Review.
    6. Cives M, Simone V, Rizzo FM, Dicuonzo F, Cristallo Lacalamita M, Ingravallo G,Silvestris F, Dammacco F. Erdheim-Chester disease: a systematic review. Crit Rev Oncol Hematol. 2015 Jul;95(1):1-11. doi: 10.1016/j.critrevonc.2015.02.004. Epub2015 Feb 17. Review.
    7. Dhomen N, Marais R. New insight into BRAF mutations in cancer. Curr Opin GenetDev. 2007 Feb;17(1):31-9. Review.
    8. Gelb BD, Tartaglia M. Noonan Syndrome with Multiple Lentigines. 2007 Nov 30[updated 2015 May 14]. In: Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K, Amemiya A, editors. GeneReviews® [Internet]. Seattle (WA): Universityof Washington, Seattle; 1993-2020. Available fromhttp://www.ncbi.nlm.nih.gov/books/NBK1383/
    9. Harmon CM, Brown N. Langerhans Cell Histiocytosis: A Clinicopathologic Review and Molecular Pathogenetic Update. Arch Pathol Lab Med. 2015 Oct;139(10):1211-4. doi: 10.5858/arpa.2015-0199-RA. Review.
    10. Haroche J, Arnaud L, Cohen-Aubart F, Hervier B, Charlotte F, Emile JF, Amoura Z. Erdheim-Chester disease. Curr Rheumatol Rep. 2014 Apr;16(4):412. doi:10.1007/s11926-014-0412-0. Review.
    11. Rauen KA. Cardiofaciocutaneous Syndrome. 2007 Jan 18 [updated 2016 Mar 3]. In:Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K, Amemiya A,editors. GeneReviews® [Internet]. Seattle (WA): University of Washington,Seattle; 1993-2020. Available from http://www.ncbi.nlm.nih.gov/books/NBK1186/
    12. Roden AC, Hu X, Kip S, Parrilla Castellar ER, Rumilla KM, Vrana JA, VassalloR, Ryu JH, Yi ES. BRAF V600E expression in Langerhans cell histiocytosis:clinical and immunohistochemical study on 25 pulmonary and 54 extrapulmonarycases. Am J Surg Pathol. 2014 Apr;38(4):548-51. doi:10.1097/PAS.0000000000000129.
    13. Rollins BJ. Genomic Alterations in Langerhans Cell Histiocytosis. HematolOncol Clin North Am. 2015 Oct;29(5):839-51. doi: 10.1016/j.hoc.2015.06.004.Review.
    14. Romano AA, Allanson JE, Dahlgren J, Gelb BD, Hall B, Pierpont ME, Roberts AE, Robinson W, Takemoto CM, Noonan JA. Noonan syndrome: clinical features,diagnosis, and management guidelines. Pediatrics. 2010 Oct;126(4):746-59. doi:10.1542/peds.2009-3207. Epub 2010 Sep 27. Review.
    15. Salgado CM, Basu D, Nikiforova M, Bauer BS, Johnson D, Rundell V, GrunwaldtLJ, Reyes-Múgica M. BRAF mutations are also associated with neurocutaneousmelanocytosis and large/giant congenital melanocytic nevi. Pediatr Dev Pathol.2015 Jan-Feb;18(1):1-9. doi: 10.2350/14-10-1566-OA.1. Epub 2014 Dec 9.
    16. Sarkozy A, Carta C, Moretti S, Zampino G, Digilio MC, Pantaleoni F, Scioletti AP, Esposito G, Cordeddu V, Lepri F, Petrangeli V, Dentici ML, Mancini GM,Selicorni A, Rossi C, Mazzanti L, Marino B, Ferrero GB, Silengo MC, Memo L,Stanzial F, Faravelli F, Stuppia L, Puxeddu E, Gelb BD, Dallapiccola B, TartagliaM. Germline BRAF mutations in Noonan, LEOPARD, and cardiofaciocutaneoussyndromes: molecular diversity and associated phenotypic spectrum. Hum Mutat.2009 Apr;30(4):695-702. doi: 10.1002/humu.20955.
    17. Satoh T, Smith A, Sarde A, Lu HC, Mian S, Trouillet C, Mufti G, Emile JF,Fraternali F, Donadieu J, Geissmann F. B-RAF mutant alleles associated withLangerhans cell histiocytosis, a granulomatous pediatric disease. PLoS One.2012;7(4):e33891. doi: 10.1371/journal.pone.0033891. Epub 2012 Apr 10. Erratumin: PLoS One. 2012;7(6).doi:10.1371/annotation/74a67f4e-a536-4b3f-a350-9a4c1e6bebbd. Mian, Sophie[corrected to Mian, Syed].
    18. Zebary A, Omholt K, van Doorn R, Ghiorzo P, Harbst K, Hertzman Johansson C,Höiom V, Jönsson G, Pjanova D, Puig S, Scarra GB, Harland M, Olsson H, EgyhaziBrage S, Palmer J, Kanter-Lewensohn L, Vassilaki I, Hayward NK, Newton-Bishop J, Gruis NA, Hansson J; Melanoma Genetics Consortium (GenoMEL). Somatic BRAF andNRAS mutations in familial melanomas with known germline CDKN2A status: a GenoMELstudy. J Invest Dermatol. 2014 Jan;134(1):287-290. doi: 10.1038/jid.2013.270.Epub 2013 Jun 14.
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