Fragile Sites

Grant R Sutherland, Women's and Children's Hospital, Adelaide, Australia

Published online: April 2007

DOI: 10.1002/9780470015902.a0005547.pub2

Fragile sites are specific points on chromosomes that show nonrandom gaps or breaks when the cells from which the chromosomes have been prepared have been exposed to a specific chemical agent or condition of tissue culture. Hence a fragile site is an area of chromatin which is not compacted when viewed in mitosis.

Keywords: fragile X syndrome; Jacobsen syndrome; trinucleotide repeat; fragile site; FRAXA; FRAXE

Figure 1. Partial metaphases showing the appearance of various fragile sites (arrowed): (a) the fragile X (FRAXA); (b) common fragile site FRA3B; (c) common BrdU-inducible fragile site FRA6D; (d) rare distamycin A-inducible fragile site FRA16B showing duplication of chromosome material distal to the fragile site; (e) rare folate-sensitive fragile site FRA22A; and (f) rare folate-sensitive fragile site FRA2B. (Courtesy of Elizabeth Baker.)
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 References
    Hewett DR, Handt O, Hobson L et al. (1998) FRA10B structure reveals common elements in repeat expansion and chromosomal fragile site genesis. Molecular Cell 1: 773–781.
    book Human Genome Nomenclature Database (2006) http://www.gene.ucl.ac.uk/cgi-bin/nomenclature/searchgenes.pl (Lists approved names, literature aliases and withdrawn symbols, with links to further information).
    Inoue H, Ishii H, Alder H et al. (1997) Sequence of the FRA3B common fragile region: implications for the mechanisms of FHIT deletion. Proceedings of the National Academy of Sciences of the USA 94: 14584–14589.
    Nolin SL, Brown WT, Glicksman A et al. (2003) Expansion of the fragile X CGG repeat in females with premutation or intermediate alleles. American Journal of Human Genetics 72: 454–464.
    Ried K, Finnis M, Hobson L et al. (2000) Common chromosomal fragile site FRA16D sequence: identification of the FOR gene spanning FRA16D and homozygous deletions and translocation breakpoints in cancer cells. Human Molecular Genetics 9: 1651–1663.
    Sherman SL (2000) Premature ovarian failure in the fragile X syndrome. American Journal of Medical Genetics 97: 189–194.
    Sherman SC, Jacobs PA, Morton NE et al. (1985) Further segregation analysis of the fragile X syndrome with special reference to transmitting males. Human Genetics 69: 289–299.
    book Sutherland GR (1991) "The detection of fragile sites on human chromosomes". In: Adolph KW (ed.) Advanced Techniques in Chromosome Research, pp. 203–222. New York, NY: Marcel Dekker
    book Sutherland GR (1993) "Human fragile sites". In: O’Brien SJ (ed.) Genetic Maps, vol. VI, pp. 5.264–5.267. Woodbury, NY: Cold Spring Harbor Laboratory Press
    Turner G, Webb T, Wake S and Robinson H (1996) Prevalence of fragile X syndrome. American Journal of Medical Genetics 64: 196–197.
    Willemsen R, Mientjes E and Oostra BA (2005) FXTAS: a progressive neurologic syndrome associated with Fragile X premutation. Current Neurology and Neuroscience Reports 5: 405–410.
    Yu S, Mangelsdorf M, Hewett D et al. (1997) Human chromosomal fragile site FRA16B is an amplified AT-rich minisatellite repeat. Cell 88: 367–374.
 Further Reading
    Gecz J and Sutherland GR (2003) (eds) Nucleotide and protein expansions and human disease. Cytogenetics and Genome Research 100: 1–298.
    book Hagerman RJ and Cronister A (1996) Fragile X Syndrome, 2nd edn Baltimore, MD: Johns Hopkins University Press.
    ePath NCBI (2006) Fragile site, folic acid type, rare, fra(X)(q28) (FRAXE); Locus ID: 2481. LocusLink: http://www.ncbi.nlm.nih.gov/LocusLink/LocRpt.cgi?l=2481
    ePath NCBI (2006) Fragile site, folic acid type, rare, fra(11)(q23.3) (FRA11B); Locus ID: 2439. LocusLink: http://www.ncbi.nlm.nih.gov/LocusLink/LocRpt.cgi?l=2439
    ePath NCBI (2006) Fragile X mental retardation 1 (FMR1); Locus ID: 2332. LocusLink: http://www.ncbi.nlm.nih.gov/LocusLink/LocRpt.cgi?l=2332
    ePath OMIM (2006) Fragile site, folic acid type, rare, fra(X)(q28) (FRAXE); MIM number: 309548. http://www.ncbi.nlm.nih.gov/htbin-post/Omim/ dispmim?309548
    ePath OMIM (2006) Fragile site, folic acid type, rare, fra(11)(q23.3) (FRA11B); MIM number: 600651. http://www.ncbi.nlm.nih.gov/htbin-post/Omim/ dispmim?600651
    ePath OMIM (2006) Fragile X mental retardation 1 (FMR1); MIM number: 309550. http://www.ncbi.nlm.nih.gov/htbin-post/Omim/ dispmim?309550
    Schwartz M, Zlotorynski E and Kerem B (2006) The molecular basis of common and rare fragile sites. Cancer Letters 232: 13–26.
    book Sutherland GR, Baker E and Richards RI (1996) "Fragile sites". Encyclopedia of Molecular Biology and Molecular Medicine, vol. 2, pp. 313–318. New York, NY: Wiley-Interscience.
    book Sutherland GR and Hecht F (1985) Fragile Sites on Human Chromosomes. New York, NY: Oxford University Press.
    Sutherland GR and Richards RI (1999) Fragile sites – cytogenetic similarity with molecular diversity. American Journal of Human Genetics 64: 354–359.
    book Wells RD and Warren ST (1998) Genetic Instabilities and Hereditary Neurological Diseases. San Diego, CA: Academic Press.

Related Sub-Topics:

Nucleic Acid Structure | Techniques and Tools in Clinical Genetics | Chromosomes and Chromatin Modifications | DNA Structure and Function | Techniques and Tools in Molecular Biology | DNA Damage and Repair
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Article Title: Fragile Sites
 
How to Cite close
Sutherland, Grant R(Apr 2007) Fragile Sites. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0005547.pub2]