Document Detail

FMR1 in global populations.
MedLine Citation:
PMID:  8644711     Owner:  NLM     Status:  MEDLINE    
Fragile X syndrome, a frequent form of inherited mental retardation, results from the unstable expansion of a cryptic CGG repeat within the 5' UTR region of the FMR1 gene. The CGG repeat is normally polymorphic in length, and the content is frequently interrupted by AGG triplets. These interruptions are believed to stabilize the repeat, and their absence, leading to long tracts of perfect CGG repeats, may give rise to predisposed alleles. In order to examine the stability of normal FMR1 alleles, the repeat length of 345 chromosomes from nine global populations was examined with the content also determined from 114 chromosomes as assessed by automated DNA sequencing. The FMR1 alleles, defined by the CGG repeat, as well as by the haplotypes of nearby polymorphic loci, were very heterogeneous, although the level of variation correlated with the age and/or genetic history of a particular population. Native American alleles, interrupted by three AGG repeats, exhibited marked stability over 7,000 years. However, in older African populations, parsimony analysis predicts the occasional loss of an AGG, leading to more perfect CGG repeats. These data therefore support the suggestion that AGG interruptions enhance the stability of the FMR1 repeat and indicate that the rare loss of these interruptions leads to alleles with longer perfect CGG-repeat tracts.
C B Kunst; C Zerylnick; L Karickhoff; E Eichler; J Bullard; M Chalifoux; J J Holden; A Torroni; D L Nelson; S T Warren
Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  American journal of human genetics     Volume:  58     ISSN:  0002-9297     ISO Abbreviation:  Am. J. Hum. Genet.     Publication Date:  1996 Mar 
Date Detail:
Created Date:  1996-07-16     Completed Date:  1996-07-16     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  0370475     Medline TA:  Am J Hum Genet     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  513-22     Citation Subset:  IM    
Howard Hughes Medical Institute, Departments of Biochemistry and Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA.
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MeSH Terms
Base Sequence
Continental Population Groups / genetics*
Fragile X Mental Retardation Protein
Fragile X Syndrome / genetics*
Gene Frequency
Molecular Sequence Data
Nerve Tissue Proteins / genetics*
Polymorphism, Genetic
RNA-Binding Proteins*
Sequence Analysis, DNA / methods
Trinucleotide Repeats*
Grant Support
Reg. No./Substance:
0/FMR1 protein, human; 0/Nerve Tissue Proteins; 0/RNA-Binding Proteins; 139135-51-6/Fragile X Mental Retardation Protein

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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