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Genetics Home Reference: your guide to understanding genetic conditions
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FLNB

Reviewed September 2011

What is the official name of the FLNB gene?

The official name of this gene is “filamin B, beta.”

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

What is the normal function of the FLNB gene?

The FLNB gene provides instructions for making a protein called filamin B. This protein helps build the network of protein filaments (cytoskeleton) that gives structure to cells and allows them to change shape and move. Filamin B attaches (binds) to another protein called actin and helps the actin to form the branching network of filaments that makes up the cytoskeleton. It also links actin to many other proteins to perform various functions within the cell, including the cell signaling that helps determine how the cytoskeleton will change as tissues grow and take shape during development.

Filamin B is involved in the development of the skeleton before birth. It is active (expressed) in many cells and tissues of the body, including cartilage-forming cells called chondrocytes. Cartilage is a tough, flexible tissue that makes up much of the skeleton during early development. Most cartilage is later converted to bone (a process called ossification), except for the cartilage that continues to cover and protect the ends of bones and is present in the nose, airways (trachea and bronchi), and external ears. Filamin B appears to be important for normal cell growth and division (proliferation) and maturation (differentiation) of chondrocytes and for the ossification of cartilage.

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

atelosteogenesis type 1 - caused by mutations in the FLNB gene

At least seven FLNB gene mutations have been identified that cause atelosteogenesis type 1, a disorder that affects the development of bones throughout the body. The mutations change single protein building blocks (amino acids) in the filamin B protein or delete a small section of the protein sequence, resulting in an abnormal protein. This abnormal protein appears to have a new, atypical function that interferes with normal proliferation or differentiation of chondrocytes, impairing ossification and leading to the signs and symptoms of atelosteogenesis type 1.

atelosteogenesis type 3 - caused by mutations in the FLNB gene

At least six FLNB gene mutations have been identified that cause atelosteogenesis type 3, a disorder that affects the development of bones throughout the body. These mutations change single amino acids in the filamin B protein or delete a small section of the protein sequence, resulting in an abnormal protein. This abnormal protein appears to have a new, atypical function that interferes with normal proliferation or differentiation of chondrocytes, impairing ossification and leading to the signs and symptoms of atelosteogenesis type 3.

boomerang dysplasia - caused by mutations in the FLNB gene

At least two FLNB gene mutations have been identified that cause boomerang dysplasia, a disorder that affects the development of bones throughout the body. These mutations change single amino acids in the filamin B protein or delete a small section of the protein sequence, resulting in an abnormal protein. This abnormal protein appears to have a new, atypical function that interferes with normal proliferation or differentiation of chondrocytes, impairing ossification and leading to the signs and symptoms of boomerang dysplasia.

Larsen syndrome - caused by mutations in the FLNB gene

At least 13 FLNB gene mutations have been identified that cause Larsen syndrome, a disorder that affects the development of bones throughout the body. These mutations change single amino acids in the filamin B protein or delete a small section of the protein sequence, resulting in an abnormal protein. This abnormal protein appears to have a new, atypical function that interferes with normal proliferation or differentiation of chondrocytes, impairing ossification and leading to the signs and symptoms of Larsen syndrome.

It is not clear why similar mutations in the FLNB gene can result in four different disorders: atelosteogenesis type 1, atelosteogenesis type 3, boomerang dysplasia, or Larsen syndrome. Certain mutations in regions of the FLNB gene known as exons 2 through 5 seem to have the most harmful effects, usually resulting in the more severe disorders, atelosteogenesis type 1 and boomerang dysplasia. Atelosteogenesis type 3 and Larsen syndrome, which are less severe, are usually caused by apparently milder mutations in exons 2 through 5 or by mutations in exons 27 through 33. In a few cases, the same mutation has been associated with more than one of these disorders in different people.

spondylocarpotarsal synostosis syndrome - caused by mutations in the FLNB gene

At least five FLNB gene mutations have been identified that cause spondylocarpotarsal synostosis syndrome, a disorder that affects the development of bones throughout the body. These mutations, which may occur in any region of the gene, result in the production of an abnormally short filamin B protein that is unstable and breaks down rapidly. Loss of the filamin B protein appears to result in out-of-place (ectopic) ossification, resulting in fusion of the bones in the spine, wrists, and ankles and other signs and symptoms of spondylocarpotarsal synostosis syndrome.

other disorders - associated with the FLNB gene

Several common variations (polymorphisms) in the FLNB gene have been associated with low bone mineral density (osteoporosis), which weakens the bones and makes them prone to fracture. FLNB gene variations may affect the maintenance of bone structure throughout the lifespan and result in differences in bone mineral density.

Where is the FLNB gene located?

Cytogenetic Location: 3p14.3

Molecular Location on chromosome 3: base pairs 58,008,399 to 58,172,254

The FLNB gene is located on the short (p) arm of chromosome 3 at position 14.3.

The FLNB gene is located on the short (p) arm of chromosome 3 at position 14.3.

More precisely, the FLNB gene is located from base pair 58,008,399 to base pair 58,172,254 on chromosome 3.

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 FLNB?

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

  • ABP-278
  • ABP-280 homolog
  • actin-binding-like protein
  • actin binding protein 278
  • beta-filamin
  • FH1
  • filamin-3
  • filamin-B
  • filamin homolog 1
  • FLN1L
  • FLN-B
  • FLNB_HUMAN
  • LRS1
  • TABP
  • TAP
  • thyroid autoantigen
  • truncated ABP
  • truncated actin-binding protein

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 FLNB?

acids ; actin ; atypical ; bone mineral density ; bronchi ; cartilage ; cell ; cytoskeleton ; differentiation ; dysplasia ; ectopic ; expressed ; gene ; mineral ; mutation ; ossification ; osteoporosis ; proliferation ; protein ; protein sequence ; syndrome ; thyroid ; tissue

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

References

  • Bicknell LS, Farrington-Rock C, Shafeghati Y, Rump P, Alanay Y, Alembik Y, Al-Madani N, Firth H, Karimi-Nejad MH, Kim CA, Leask K, Maisenbacher M, Moran E, Pappas JG, Prontera P, de Ravel T, Fryns JP, Sweeney E, Fryer A, Unger S, Wilson LC, Lachman RS, Rimoin DL, Cohn DH, Krakow D, Robertson SP. A molecular and clinical study of Larsen syndrome caused by mutations in FLNB. J Med Genet. 2007 Feb;44(2):89-98. Epub 2006 Jun 26. (http://www.ncbi.nlm.nih.gov/pubmed/16801345?dopt=Abstract)
  • Bicknell LS, Morgan T, Bonafé L, Wessels MW, Bialer MG, Willems PJ, Cohn DH, Krakow D, Robertson SP. Mutations in FLNB cause boomerang dysplasia. J Med Genet. 2005 Jul;42(7):e43. (http://www.ncbi.nlm.nih.gov/pubmed/15994868?dopt=Abstract)
  • Farrington-Rock C, Firestein MH, Bicknell LS, Superti-Furga A, Bacino CA, Cormier-Daire V, Le Merrer M, Baumann C, Roume J, Rump P, Verheij JB, Sweeney E, Rimoin DL, Lachman RS, Robertson SP, Cohn DH, Krakow D. Mutations in two regions of FLNB result in atelosteogenesis I and III. Hum Mutat. 2006 Jul;27(7):705-10. (http://www.ncbi.nlm.nih.gov/pubmed/16752402?dopt=Abstract)
  • OMIM: FILAMIN B (http://omim.org/entry/603381)
  • Isidor B, Cormier-Daire V, Le Merrer M, Lefrancois T, Hamel A, Le Caignec C, David A, Jacquemont S. Autosomal dominant spondylocarpotarsal synostosis syndrome: phenotypic homogeneity and genetic heterogeneity. Am J Med Genet A. 2008 Jun 15;146A(12):1593-7. doi: 10.1002/ajmg.a.32217. (http://www.ncbi.nlm.nih.gov/pubmed/18470895?dopt=Abstract)
  • Krakow D, Robertson SP, King LM, Morgan T, Sebald ET, Bertolotto C, Wachsmann-Hogiu S, Acuna D, Shapiro SS, Takafuta T, Aftimos S, Kim CA, Firth H, Steiner CE, Cormier-Daire V, Superti-Furga A, Bonafe L, Graham JM Jr, Grix A, Bacino CA, Allanson J, Bialer MG, Lachman RS, Rimoin DL, Cohn DH. Mutations in the gene encoding filamin B disrupt vertebral segmentation, joint formation and skeletogenesis. Nat Genet. 2004 Apr;36(4):405-10. Epub 2004 Feb 29. (http://www.ncbi.nlm.nih.gov/pubmed/14991055?dopt=Abstract)
  • Li GH, Kung AW, Huang QY. Common variants in FLNB/CRTAP, not ARHGEF3 at 3p, are associated with osteoporosis in southern Chinese women. Osteoporos Int. 2010 Jun;21(6):1009-20. doi: 10.1007/s00198-009-1043-6. Epub 2009 Sep 1. (http://www.ncbi.nlm.nih.gov/pubmed/19727905?dopt=Abstract)
  • NCBI Gene (http://www.ncbi.nlm.nih.gov/gene/2317)
  • Sawyer GM, Clark AR, Robertson SP, Sutherland-Smith AJ. Disease-associated substitutions in the filamin B actin binding domain confer enhanced actin binding affinity in the absence of major structural disturbance: Insights from the crystal structures of filamin B actin binding domains. J Mol Biol. 2009 Jul 31;390(5):1030-47. doi: 10.1016/j.jmb.2009.06.009. Epub 2009 Jun 6. (http://www.ncbi.nlm.nih.gov/pubmed/19505475?dopt=Abstract)
  • Wilson SG, Jones MR, Mullin BH, Dick IM, Richards JB, Pastinen TM, Grundberg E, Ljunggren O, Surdulescu GL, Dudbridge F, Elliott KS, Cervino AC, Spector TD, Prince RL. Common sequence variation in FLNB regulates bone structure in women in the general population and FLNB mRNA expression in osteoblasts in vitro. J Bone Miner Res. 2009 Dec;24(12):1989-97. doi: 10.1359/jbmr.090530. (http://www.ncbi.nlm.nih.gov/pubmed/19453265?dopt=Abstract)
  • Zhang D, Herring JA, Swaney SS, McClendon TB, Gao X, Browne RH, Rathjen KE, Johnston CE, Harris S, Cain NM, Wise CA. Mutations responsible for Larsen syndrome cluster in the FLNB protein. J Med Genet. 2006 May;43(5):e24. (http://www.ncbi.nlm.nih.gov/pubmed/16648377?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: September 2011
Published: November 17, 2014