Document Detail


Fragile-X syndrome: unique genetics of the heritable unstable element.
MedLine Citation:
PMID:  1570846     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The fragile site at Xq27.3 is an unstable microsatellite repeat, p(CCG)n. In fragile-X syndrome pedigrees, this sequence exhibits variable amplification, the length of which correlates with fragile-site expression. There is a direct relationship between increased p(CCG)n copy number and propensity for instability: individuals having large amplifications exhibit somatic variation due to increased instability. The instability of the p(CCG)n repeat, when transmitted through affected pedigrees, explains the unusual segregation patterns of fragile-X phenotype, referred to as the Sherman paradox. All individuals of fragile-X genotype were found (where testing was possible) to have a parent with amplified p(CCG)n repeat, indicating that few, if any, cases of fragile-X syndrome are not familial.
Authors:
S Yu; J Mulley; D Loesch; G Turner; A Donnelly; A Gedeon; D Hillen; E Kremer; M Lynch; M Pritchard
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  American journal of human genetics     Volume:  50     ISSN:  0002-9297     ISO Abbreviation:  Am. J. Hum. Genet.     Publication Date:  1992 May 
Date Detail:
Created Date:  1992-05-26     Completed Date:  1992-05-26     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:  968-80     Citation Subset:  IM    
Affiliation:
Department of Cytogenetics and Molecular Genetics, Adelaide Children's Hospital, Australia.
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MeSH Terms
Descriptor/Qualifier:
Blotting, Southern
Deoxyribonucleases, Type II Site-Specific / metabolism
Female
Fragile X Syndrome / genetics*
Genetic Variation
Heterozygote
Humans
Male
Methylation
Mutation
Pedigree
Phenotype
Polymerase Chain Reaction
Repetitive Sequences, Nucleic Acid / genetics*
X Chromosome*
Chemical
Reg. No./Substance:
EC 3.1.21.4/CTGCAG-specific type II deoxyribonucleases; EC 3.1.21.4/Deoxyribonucleases, Type II Site-Specific
Comments/Corrections

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