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MeSH Review

Fragile X Syndrome

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Disease relevance of Fragile X Syndrome


Psychiatry related information on Fragile X Syndrome


High impact information on Fragile X Syndrome


Chemical compound and disease context of Fragile X Syndrome


Biological context of Fragile X Syndrome

  • Methylation of the expanded repeats correlates with down-regulation of transcription of FMR1; thus fragile X syndrome is postulated to be due to a loss of function of the FMR1 gene product, and this has been demonstrated at the protein level [15].
  • Recent advances in the identification of the mRNA ligands that are bound by FMRP, the RNA sequence and structure required for FMRP-RNA interaction, and the physiological consequences of FMRP deficiency in the brain are important steps towards understanding the molecular pathogenesis of fragile X syndrome, and learning and memory in general [21].
  • An n-allele model is developed for the FMR1 locus, which causes the fragile X syndrome, where n is the number of triplet repeats in the first exon [22].
  • 3. The cytogenetic expression of FRAXE is thought to be associated with mental handicap, but this is usually mild compared to that of the more common fragile X syndrome that is associated with the expression of the FRAXA fragile site [23].
  • These data support the nonpenetrant status of premutation carriers of fragile X syndrome and suggest that the occasional case reports to the contrary may reflect either other causes, including low-level mosaicism for larger, methylated FMR1 alleles, or simply coincidence [24].

Anatomical context of Fragile X Syndrome


Gene context of Fragile X Syndrome

  • Our data indicate that the frequency of SLC6A8 mutations in the XLMR population is close to that of CGG expansions in FMR1, the gene responsible for fragile-X syndrome [30].
  • The expression of FRAXA is associated with the fragile X syndrome, the most prevalent form of inherited mental retardation whilst the expression of FRAXE is associated with a rarer and comparatively milder form of mental handicap [31].
  • Sensorimotor gating abnormalities in young males with fragile X syndrome and Fmr1-knockout mice [32].
  • A further two families had consistent expression of a different folate sensitive fragile site, FRAXE, close to FRAXA but not associated with fragile X syndrome and not detectable with the pfxa3 probe [33].
  • Thus, a dominant negative effect of abnormal multimeric protein complexes lacking FMRP (e.g. by modification of FXR1 and FXR2 protein functions) may result in the fragile X syndrome phenotype [34].

Analytical, diagnostic and therapeutic context of Fragile X Syndrome


  1. A common fragile site at Xq27: theoretical and practical implications. Ledbetter, S.A., Ledbetter, D.H. Am. J. Hum. Genet. (1988) [Pubmed]
  2. Moderate instability of the trinucleotide repeat in spino bulbar muscular atrophy. Biancalana, V., Serville, F., Pommier, J., Julien, J., Hanauer, A., Mandel, J.L. Hum. Mol. Genet. (1992) [Pubmed]
  3. Myotonic dystrophy: another case of too many repeats? Shelbourne, P., Johnson, K. Hum. Mutat. (1992) [Pubmed]
  4. Nucleotide excision repair affects the stability of long transcribed (CTG*CAG) tracts in an orientation-dependent manner in Escherichia coli. Parniewski, P., Bacolla, A., Jaworski, A., Wells, R.D. Nucleic Acids Res. (1999) [Pubmed]
  5. Deletions in Xq26.3-q27.3 including FMR1 result in a severe phenotype in a male and variable phenotypes in females depending upon the X inactivation pattern. Wolff, D.J., Gustashaw, K.M., Zurcher, V., Ko, L., White, W., Weiss, L., Van Dyke, D.L., Schwartz, S., Willard, H.F. Hum. Genet. (1997) [Pubmed]
  6. The fragile X syndrome protein FMRP associates with BC1 RNA and regulates the translation of specific mRNAs at synapses. Zalfa, F., Giorgi, M., Primerano, B., Moro, A., Di Penta, A., Reis, S., Oostra, B., Bagni, C. Cell (2003) [Pubmed]
  7. Courting a cure for fragile X. Dölen, G., Bear, M.F. Neuron (2005) [Pubmed]
  8. Unstable genes--unstable mind? Petronis, A., Kennedy, J.L. The American journal of psychiatry. (1995) [Pubmed]
  9. Effects of long-acting propranolol on agonistic and stereotyped behaviors in a man with pervasive developmental disorder and fragile X syndrome: a double-blind, placebo-controlled study. Cohen, I.L., Tsiouris, J.A., Pfadt, A. Journal of clinical psychopharmacology. (1991) [Pubmed]
  10. Behavioral assessment of social anxiety in females with Turner or fragile X syndrome. Lesniak-Karpiak, K., Mazzocco, M.M., Ross, J.L. Journal of autism and developmental disorders. (2003) [Pubmed]
  11. Brahma links the SWI/SNF chromatin-remodeling complex with MeCP2-dependent transcriptional silencing. Harikrishnan, K.N., Chow, M.Z., Baker, E.K., Pal, S., Bassal, S., Brasacchio, D., Wang, L., Craig, J.M., Jones, P.L., Sif, S., El-Osta, A. Nat. Genet. (2005) [Pubmed]
  12. Sequence-specific RNA binding by a Nova KH domain: implications for paraneoplastic disease and the fragile X syndrome. Lewis, H.A., Musunuru, K., Jensen, K.B., Edo, C., Chen, H., Darnell, R.B., Burley, S.K. Cell (2000) [Pubmed]
  13. Acetylated histones are associated with FMR1 in normal but not fragile X-syndrome cells. Coffee, B., Zhang, F., Warren, S.T., Reines, D. Nat. Genet. (1999) [Pubmed]
  14. Characterization of the full fragile X syndrome mutation in fetal gametes. Malter, H.E., Iber, J.C., Willemsen, R., de Graaff, E., Tarleton, J.C., Leisti, J., Warren, S.T., Oostra, B.A. Nat. Genet. (1997) [Pubmed]
  15. Intragenic loss of function mutations demonstrate the primary role of FMR1 in fragile X syndrome. Lugenbeel, K.A., Peier, A.M., Carson, N.L., Chudley, A.E., Nelson, D.L. Nat. Genet. (1995) [Pubmed]
  16. Dilantin and the fragile X syndrome. Hagerman, R.J., Levitas, A. N. Engl. J. Med. (1983) [Pubmed]
  17. Folic acid blinded trial in identical twins with fragile X syndrome. Rosenblatt, D.S., Duschenes, E.A., Hellstrom, F.V., Golick, M.S., Vekemans, M.J., Zeesman, S.F., Andermann, E. Am. J. Hum. Genet. (1985) [Pubmed]
  18. Intracellular folate distribution in cultured fibroblasts from patients with the fragile X syndrome. Popovich, B.W., Rosenblatt, D.S., Cooper, B.A., Vekemans, M. Am. J. Hum. Genet. (1983) [Pubmed]
  19. Fragile X syndrome: search for phenotypic manifestations at loci for hypoxanthine phosphoribosyltransferase and glucose-6-phosphate dehydrogenase. Mareni, C., Migeon, B.R. Am. J. Hum. Genet. (1981) [Pubmed]
  20. Cyclic AMP metabolism in fragile X syndrome. Berry-Kravis, E., Huttenlocher, P.R. Ann. Neurol. (1992) [Pubmed]
  21. New insights into fragile X syndrome: from molecules to neurobehaviors. Jin, P., Warren, S.T. Trends Biochem. Sci. (2003) [Pubmed]
  22. An n-allele model for progressive amplification in the FMR1 locus. Morris, A., Morton, N.E., Collins, A., Macpherson, J., Nelson, D., Sherman, S. Proc. Natl. Acad. Sci. U.S.A. (1995) [Pubmed]
  23. A study of FRAXE in mentally retarded individuals referred for fragile X syndrome (FRAXA) testing in the United Kingdom. Knight, S.J., Ritchie, R.J., Chakrabarti, L., Cross, G., Taylor, G.R., Mueller, R.F., Hurst, J., Paterson, J., Yates, J.R., Dow, D.J., Davies, K.E. Am. J. Hum. Genet. (1996) [Pubmed]
  24. Quantitative comparison of FMR1 gene expression in normal and premutation alleles. Feng, Y., Lakkis, L., Devys, D., Warren, S.T. Am. J. Hum. Genet. (1995) [Pubmed]
  25. Absence of expression of the FMR-1 gene in fragile X syndrome. Pieretti, M., Zhang, F.P., Fu, Y.H., Warren, S.T., Oostra, B.A., Caskey, C.T., Nelson, D.L. Cell (1991) [Pubmed]
  26. Molecular dissection of the events leading to inactivation of the FMR1 gene. Pietrobono, R., Tabolacci, E., Zalfa, F., Zito, I., Terracciano, A., Moscato, U., Bagni, C., Oostra, B., Chiurazzi, P., Neri, G. Hum. Mol. Genet. (2005) [Pubmed]
  27. Butyrate and acetyl-carnitine inhibit the cytogenetic expression of the fragile X in vitro. Pomponi, M.G., Neri, G. Am. J. Med. Genet. (1994) [Pubmed]
  28. Effects of Fragile X syndrome and an FMR1 knockout mouse model on forebrain neuronal cell biology. Churchill, J.D., Beckel-Mitchener, A., Weiler, I.J., Greenough, W.T. Microsc. Res. Tech. (2002) [Pubmed]
  29. Neural progenitor cells from an adult patient with fragile X syndrome. Schwartz, P.H., Tassone, F., Greco, C.M., Nethercott, H.E., Ziaeian, B., Hagerman, R.J., Hagerman, P.J. BMC Med. Genet. (2005) [Pubmed]
  30. High prevalence of SLC6A8 deficiency in X-linked mental retardation. Rosenberg, E.H., Almeida, L.S., Kleefstra, T., deGrauw, R.S., Yntema, H.G., Bahi, N., Moraine, C., Ropers, H.H., Fryns, J.P., deGrauw, T.J., Jakobs, C., Salomons, G.S. Am. J. Hum. Genet. (2004) [Pubmed]
  31. The cloning of FRAXF: trinucleotide repeat expansion and methylation at a third fragile site in distal Xqter. Ritchie, R.J., Knight, S.J., Hirst, M.C., Grewal, P.K., Bobrow, M., Cross, G.S., Davies, K.E. Hum. Mol. Genet. (1994) [Pubmed]
  32. Sensorimotor gating abnormalities in young males with fragile X syndrome and Fmr1-knockout mice. Frankland, P.W., Wang, Y., Rosner, B., Shimizu, T., Balleine, B.W., Dykens, E.M., Ornitz, E.M., Silva, A.J. Mol. Psychiatry (2004) [Pubmed]
  33. Experience with direct molecular diagnosis of fragile X. Mulley, J.C., Yu, S., Gedeon, A.K., Donnelly, A., Turner, G., Loesch, D., Chapman, C.J., Gardner, R.J., Richards, R.I., Sutherland, G.R. J. Med. Genet. (1992) [Pubmed]
  34. Expression of FMR1, FXR1, and FXR2 genes in human prenatal tissues. Agulhon, C., Blanchet, P., Kobetz, A., Marchant, D., Faucon, N., Sarda, P., Moraine, C., Sittler, A., Biancalana, V., Malafosse, A., Abitbol, M. J. Neuropathol. Exp. Neurol. (1999) [Pubmed]
  35. Noninvasive test for fragile X syndrome, using hair root analysis. Willemsen, R., Anar, B., De Diego Otero, Y., de Vries, B.B., Hilhorst-Hofstee, Y., Smits, A., van Looveren, E., Willems, P.J., Galjaard, H., Oostra, B.A. Am. J. Hum. Genet. (1999) [Pubmed]
  36. A fragile gene. Oostra, B.A., Willems, P.J. Bioessays (1995) [Pubmed]
  37. Evaluation of the fragile X (FRAXA) syndrome with methylation-sensitive PCR. Weinhäusel, A., Haas, O.A. Hum. Genet. (2001) [Pubmed]
  38. The nature of the spatial deficit in young females with Fragile-X syndrome: a neuropsychological and molecular perspective. Cornish, K.M., Munir, F., Cross, G. Neuropsychologia. (1998) [Pubmed]
  39. Accelerated prenatal diagnosis of fragile X syndrome by polymerase chain reaction restriction fragment detection. Dobkin, C., Ding, X., Li, S., Houck, G., Nolin, S.L., Glicksman, A., Zhong, N., Jenkins, E.C., Brown, W.T. Am. J. Med. Genet. (1999) [Pubmed]
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