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Genetics Home Reference: your guide to understanding genetic conditions
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FBN1

Reviewed March 2015

What is the official name of the FBN1 gene?

The official name of this gene is “fibrillin 1.”

FBN1 is the gene's official symbol. The FBN1 gene is also known by other names, listed below.

What is the normal function of the FBN1 gene?

The FBN1 gene provides instructions for making a large protein called fibrillin-1. This protein is transported out of cells into the extracellular matrix, which is an intricate lattice of proteins and other molecules that forms in the spaces between cells. In this matrix, molecules of fibrillin-1 attach (bind) to each other and to other proteins to form threadlike filaments called microfibrils. Microfibrils form elastic fibers, which enable the skin, ligaments, and blood vessels to stretch. Microfibrils also provide support to more rigid tissues such as bones and the tissues that support the nerves, muscles, and lenses of the eyes.

Microfibrils store a protein called transforming growth factor beta (TGF-β), a critical growth factor. TGF-β affects development by helping to control the growth and division (proliferation) of cells, the process by which cells mature to carry out specific functions (differentiation), cell movement (motility), and the self-destruction of cells (apoptosis). Microfibrils help regulate the availability of TGF-β, which is turned off (inactivated) when stored in microfibrils and turned on (activated) when released.

How are changes in the FBN1 gene related to health conditions?

acromicric dysplasia - caused by mutations in the FBN1 gene

At least nine FBN1 gene mutations have been identified in people with acromicric dysplasia. This condition is characterized by severely short stature, short limbs, stiff joints, and distinctive facial features.

FBN1 gene mutations that cause acromicric dysplasia are located in an area of the gene called exons 41 and 42, and change single protein building blocks (amino acids) in a region of the fibrillin-1 protein called TGF-β binding-protein-like domain 5. The mutations result in a reduction and disorganization of the microfibrils. Without enough normal microfibrils to store TGF-β, the growth factor is abnormally active. These effects likely contribute to the physical abnormalities that occur in acromicric dysplasia, but the mechanisms are unclear.

It is unknown why the FBN1 gene mutations that cause acromicric dysplasia lead to short stature, while certain other FBN1 gene mutations that also increase TGF-β activity cause a disorder called Marfan syndrome (see below), which is characterized by tall stature.

isolated ectopia lentis - caused by mutations in the FBN1 gene

More than 30 mutations in the FBN1 gene have been found to cause isolated ectopia lentis. In this condition, the lens in one or both eyes is off-center (displaced), which leads to vision problems. Most of the FBN1 gene mutations that cause this condition change single amino acids in the fibrillin-1 protein. As a result, the production of normal fibrillin-1 protein is reduced, leading to a decrease in microfibril formation or the formation of impaired microfibrils. Without enough functional microfibrils to anchor the lens in its central position at the front of the eye, the lens becomes displaced, resulting in isolated ectopia lentis and related vision problems.

Ectopia lentis is classified as isolated when it occurs alone, without signs and symptoms affecting other body systems. However, some people initially diagnosed with isolated ectopia lentis caused by FBN1 gene mutations later develop additional features typical of a condition called Marfan syndrome (described below), such as abnormalities of the large blood vessel that distributes blood from the heart to the rest of the body (the aorta). In these cases, the diagnosis often changes from isolated ectopia lentis to Marfan syndrome.

Marfan syndrome - caused by mutations in the FBN1 gene

Researchers have identified more than 1,300 FBN1 gene mutations that cause Marfan syndrome, a disorder that affects the connective tissue supporting the body's joints and organs. Abnormalities in the connective tissue lead to heart and eye problems in people with this disorder. In addition, affected individuals are usually tall and slender with elongated fingers and toes and other skeletal abnormalities. Most of the mutations that cause Marfan syndrome change a single amino acid in the fibrillin-1 protein. The remaining FBN1 gene mutations result in an abnormal fibrillin-1 protein that cannot function properly. FBN1 gene mutations that cause Marfan syndrome reduce the amount of fibrillin-1 produced by the cell, alter the structure or stability of fibrillin-1, or impair the transport of fibrillin-1 out of the cell. These mutations lead to a severe reduction in the amount of fibrillin-1 available to form microfibrils. Without enough microfibrils, excess TGF-β growth factors are activated and elasticity in many tissues is decreased, leading to overgrowth and instability of tissues and the signs and symptoms of Marfan syndrome.

Weill-Marchesani syndrome - caused by mutations in the FBN1 gene

Mutations in the FBN1 gene have also been identified in Weill-Marchesani syndrome. One of the identified mutations deletes part of the gene, leading to the production of an unstable version of the fibrillin-1 protein. The unstable protein likely interferes with the assembly of microfibrils. Abnormal microfibrils weaken connective tissue, which causes the eye, heart, and skeletal abnormalities associated with Weill-Marchesani syndrome.

other disorders - caused by mutations in the FBN1 gene

Mutations in the FBN1 gene can cause a condition called stiff skin syndrome. This condition is characterized by very hard, thick skin covering most of the body. The abnormal skin limits movement and can lead to joint deformities called contractures that restrict the movement of certain joints. The signs and symptoms of stiff skin syndrome usually become apparent in infancy to mid-childhood.

Mutations in the FBN1 gene can cause another condition called MASS syndrome. This condition involves abnormalities in several parts of the body, including the mitral valve (one of the valves that controls blood flow through the heart), the aorta (a large blood vessel that distributes blood from the heart to the rest of the body), the skeleton, and the skin.

It is unknown why different mutations in the FBN1 gene cause such a variety of disorders.

Where is the FBN1 gene located?

Cytogenetic Location: 15q21.1

Molecular Location on chromosome 15: base pairs 48,408,305 to 48,645,787

The FBN1 gene is located on the long (q) arm of chromosome 15 at position 21.1.

The FBN1 gene is located on the long (q) arm of chromosome 15 at position 21.1.

More precisely, the FBN1 gene is located from base pair 48,408,305 to base pair 48,645,787 on chromosome 15.

See How do geneticists indicate the location of a gene? (http://ghr.nlm.nih.gov/handbook/howgeneswork/genelocation) in the Handbook.

Where can I find additional information about FBN1?

You and your healthcare professional may find the following resources about FBN1 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 FBN1 gene or gene products?

  • FBN
  • FBN1_HUMAN
  • fibrillin 1 (Marfan syndrome)
  • MFS1
  • SGS

See How are genetic conditions and genes named? (http://ghr.nlm.nih.gov/handbook/mutationsanddisorders/naming) in the Handbook.

What glossary definitions help with understanding FBN1?

acids ; amino acid ; aneurysm ; aorta ; apoptosis ; cell ; connective tissue ; diagnosis ; differentiation ; domain ; dysplasia ; elastic ; extracellular ; extracellular matrix ; familial ; gene ; growth factor ; joint ; microfibrils ; mitral valve ; proliferation ; protein ; short stature ; stature ; syndrome ; tissue

You may find definitions for these and many other terms in the Genetics Home Reference Glossary (http://ghr.nlm.nih.gov/glossary).

References

  • Adès LC, Sullivan K, Biggin A, Haan EA, Brett M, Holman KJ, Dixon J, Robertson S, Holmes AD, Rogers J, Bennetts B. FBN1, TGFBR1, and the Marfan-craniosynostosis/mental retardation disorders revisited. Am J Med Genet A. 2006 May 15;140(10):1047-58. (http://www.ncbi.nlm.nih.gov/pubmed/16596670?dopt=Abstract)
  • Arbustini E, Grasso M, Ansaldi S, Malattia C, Pilotto A, Porcu E, Disabella E, Marziliano N, Pisani A, Lanzarini L, Mannarino S, Larizza D, Mosconi M, Antoniazzi E, Zoia MC, Meloni G, Magrassi L, Brega A, Bedeschi MF, Torrente I, Mari F, Tavazzi L. Identification of sixty-two novel and twelve known FBN1 mutations in eighty-one unrelated probands with Marfan syndrome and other fibrillinopathies. Hum Mutat. 2005 Nov;26(5):494. (http://www.ncbi.nlm.nih.gov/pubmed/16222657?dopt=Abstract)
  • Brautbar A, LeMaire SA, Franco LM, Coselli JS, Milewicz DM, Belmont JW. FBN1 mutations in patients with descending thoracic aortic dissections. Am J Med Genet A. 2010 Feb;152A(2):413-6. doi: 10.1002/ajmg.a.32856. (http://www.ncbi.nlm.nih.gov/pubmed/20082464?dopt=Abstract)
  • Chandra A, Patel D, Aragon-Martin JA, Pinard A, Collod-Béroud G, Comeglio P, Boileau C, Faivre L, Charteris D, Child AH, Arno G. The revised ghent nosology; reclassifying isolated ectopia lentis. Clin Genet. 2015 Mar;87(3):284-7. doi: 10.1111/cge.12358. Epub 2014 Mar 6. (http://www.ncbi.nlm.nih.gov/pubmed/24635535?dopt=Abstract)
  • Collod-Béroud G, Boileau C. Marfan syndrome in the third Millennium. Eur J Hum Genet. 2002 Nov;10(11):673-81. Review. (http://www.ncbi.nlm.nih.gov/pubmed/12404097?dopt=Abstract)
  • Dietz HC, McIntosh I, Sakai LY, Corson GM, Chalberg SC, Pyeritz RE, Francomano CA. Four novel FBN1 mutations: significance for mutant transcript level and EGF-like domain calcium binding in the pathogenesis of Marfan syndrome. Genomics. 1993 Aug;17(2):468-75. (http://www.ncbi.nlm.nih.gov/pubmed/8406497?dopt=Abstract)
  • Faivre L, Collod-Beroud G, Callewaert B, Child A, Loeys BL, Binquet C, Gautier E, Arbustini E, Mayer K, Arslan-Kirchner M, Kiotsekoglou A, Comeglio P, Grasso M, Beroud C, Bonithon-Kopp C, Claustres M, Stheneur C, Bouchot O, Wolf JE, Robinson PN, Adès L, De Backer J, Coucke P, Francke U, De Paepe A, Boileau C, Jondeau G. Pathogenic FBN1 mutations in 146 adults not meeting clinical diagnostic criteria for Marfan syndrome: further delineation of type 1 fibrillinopathies and focus on patients with an isolated major criterion. Am J Med Genet A. 2009 May;149A(5):854-60. doi: 10.1002/ajmg.a.32809. (http://www.ncbi.nlm.nih.gov/pubmed/19353630?dopt=Abstract)
  • Faivre L, Collod-Beroud G, Loeys BL, Child A, Binquet C, Gautier E, Callewaert B, Arbustini E, Mayer K, Arslan-Kirchner M, Kiotsekoglou A, Comeglio P, Marziliano N, Dietz HC, Halliday D, Beroud C, Bonithon-Kopp C, Claustres M, Muti C, Plauchu H, Robinson PN, Adès LC, Biggin A, Benetts B, Brett M, Holman KJ, De Backer J, Coucke P, Francke U, De Paepe A, Jondeau G, Boileau C. Effect of mutation type and location on clinical outcome in 1,013 probands with Marfan syndrome or related phenotypes and FBN1 mutations: an international study. Am J Hum Genet. 2007 Sep;81(3):454-66. Epub 2007 Jul 25. (http://www.ncbi.nlm.nih.gov/pubmed/17701892?dopt=Abstract)
  • Faivre L, Gorlin RJ, Wirtz MK, Godfrey M, Dagoneau N, Samples JR, Le Merrer M, Collod-Beroud G, Boileau C, Munnich A, Cormier-Daire V. In frame fibrillin-1 gene deletion in autosomal dominant Weill-Marchesani syndrome. J Med Genet. 2003 Jan;40(1):34-6. (http://www.ncbi.nlm.nih.gov/pubmed/12525539?dopt=Abstract)
  • Glesby MJ, Pyeritz RE. Association of mitral valve prolapse and systemic abnormalities of connective tissue. A phenotypic continuum. JAMA. 1989 Jul 28;262(4):523-8. (http://www.ncbi.nlm.nih.gov/pubmed/2739055?dopt=Abstract)
  • Le Goff C, Mahaut C, Wang LW, Allali S, Abhyankar A, Jensen S, Zylberberg L, Collod-Beroud G, Bonnet D, Alanay Y, Brady AF, Cordier MP, Devriendt K, Genevieve D, Kiper PÖ, Kitoh H, Krakow D, Lynch SA, Le Merrer M, Mégarbane A, Mortier G, Odent S, Polak M, Rohrbach M, Sillence D, Stolte-Dijkstra I, Superti-Furga A, Rimoin DL, Topouchian V, Unger S, Zabel B, Bole-Feysot C, Nitschke P, Handford P, Casanova JL, Boileau C, Apte SS, Munnich A, Cormier-Daire V. Mutations in the TGFβ binding-protein-like domain 5 of FBN1 are responsible for acromicric and geleophysic dysplasias. Am J Hum Genet. 2011 Jul 15;89(1):7-14. doi: 10.1016/j.ajhg.2011.05.012. Epub 2011 Jun 16. (http://www.ncbi.nlm.nih.gov/pubmed/21683322?dopt=Abstract)
  • Loeys BL, Gerber EE, Riegert-Johnson D, Iqbal S, Whiteman P, McConnell V, Chillakuri CR, Macaya D, Coucke PJ, De Paepe A, Judge DP, Wigley F, Davis EC, Mardon HJ, Handford P, Keene DR, Sakai LY, Dietz HC. Mutations in fibrillin-1 cause congenital scleroderma: stiff skin syndrome. Sci Transl Med. 2010 Mar 17;2(23):23ra20. doi: 10.1126/scitranslmed.3000488. (http://www.ncbi.nlm.nih.gov/pubmed/20375004?dopt=Abstract)
  • Mizuguchi T, Matsumoto N. Recent progress in genetics of Marfan syndrome and Marfan-associated disorders. J Hum Genet. 2007;52(1):1-12. Epub 2006 Oct 24. Review. (http://www.ncbi.nlm.nih.gov/pubmed/17061023?dopt=Abstract)
  • NCBI Gene (http://www.ncbi.nlm.nih.gov/gene/2200)
  • Robinson PN, Arteaga-Solis E, Baldock C, Collod-Béroud G, Booms P, De Paepe A, Dietz HC, Guo G, Handford PA, Judge DP, Kielty CM, Loeys B, Milewicz DM, Ney A, Ramirez F, Reinhardt DP, Tiedemann K, Whiteman P, Godfrey M. The molecular genetics of Marfan syndrome and related disorders. J Med Genet. 2006 Oct;43(10):769-87. Epub 2006 Mar 29. Review. (http://www.ncbi.nlm.nih.gov/pubmed/16571647?dopt=Abstract)
  • Rommel K, Karck M, Haverich A, von Kodolitsch Y, Rybczynski M, Müller G, Singh KK, Schmidtke J, Arslan-Kirchner M. Identification of 29 novel and nine recurrent fibrillin-1 (FBN1) mutations and genotype-phenotype correlations in 76 patients with Marfan syndrome. Hum Mutat. 2005 Dec;26(6):529-39. (http://www.ncbi.nlm.nih.gov/pubmed/16220557?dopt=Abstract)

 

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? (http://ghr.nlm.nih.gov/handbook/consult/findingprofessional) in the Handbook.

 
Reviewed: March 2015
Published: April 20, 2015