Document Detail

The risk of fragile X premutation expansion is lower in carriers detected by general prenatal screening than in carriers from known fragile X families.
MedLine Citation:
PMID:  11142761     Owner:  NLM     Status:  MEDLINE    
The Fragile X syndrome is the most common cause of inherited mental retardation. For a female premutation carrier, the risk of having a child with a full mutation is positively correlated with the size of the premutation. The current study was performed to evaluate the risk of premutation expansion in the offspring of average-risk carriers detected by general prenatal screening. Over a 4-year period, 9,660 women underwent DNA screening for FMR1 mutation/premutation at the Tel Aviv Sourasky Medical Center. A premutation was defined as a CGG repeat number >50 in the 5' untranslated region (UTR) of exon 1 in the FMR1 gene. The study included only individuals with no family history of X-linked mental retardation or known FMR1 mutations. A premutation was found in 85 women (1 in 114), 68 of whom consented to have prenatal diagnoses in 74 pregnancies. The abnormal allele was transmitted to the offspring in 44 pregnancies. Of these, no change in allele size was noted in 35 pregnancies (79.6%), and expansion within premutation range was evident in 4 pregnancies (9%). In 5 pregnancies (11.4%), expansion to the full mutation was noted. This occurred only in carriers having more than 90 repeats. We conclude that the likelihood of Fragile X premutation expansion to full mutation is significantly lower in individuals ascertained by general prenatal carrier testing than in those from known Fragile X families.
E Geva; Y Yaron; R Shomrat; A Ben-Yehuda; S Zabari; H Peretz; T Naiman; H Yeger; A Orr-Urtreger
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Genetic testing     Volume:  4     ISSN:  1090-6576     ISO Abbreviation:  Genet. Test.     Publication Date:  2000  
Date Detail:
Created Date:  2000-12-15     Completed Date:  2001-02-01     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  9802546     Medline TA:  Genet Test     Country:  United States    
Other Details:
Languages:  eng     Pagination:  289-92     Citation Subset:  IM    
Department of Obstetrics and Gynecology, Tel Aviv Sourasky Medical Center, Israel.
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MeSH Terms
Fragile X Mental Retardation Protein
Fragile X Syndrome / genetics*
Genetic Testing*
Heterozygote Detection*
Nerve Tissue Proteins / genetics*
Prenatal Diagnosis
RNA-Binding Proteins*
Risk Assessment
Trinucleotide Repeats
Reg. No./Substance:
0/FMR1 protein, human; 0/Nerve Tissue Proteins; 0/RNA-Binding Proteins; 139135-51-6/Fragile X Mental Retardation Protein

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