scholarly journals Simplified strategy for rapid first-line screening of fragile X syndrome: closed-tube triplet-primed PCR and amplicon melt peak analysis

2015 ◽  
Vol 17 ◽  
Author(s):  
Indhu-Shree Rajan-Babu ◽  
Hai-Yang Law ◽  
Chui-Sheun Yoon ◽  
Caroline G. Lee ◽  
Samuel S. Chong
Keyword(s):  
Fragile X Syndrome ◽  
Large Scale ◽  
Fragile X ◽  
Population Based ◽  
Molecular Diagnostic ◽  
First Line ◽  
Cgg Repeat ◽  
Screening Programs ◽  
Repeat Size ◽  
Closed Tube

Premutation and full-mutation hyperexpansion of CGG-triplets in the X-linkedFragile X Mental Retardation 1(FMR1) gene have been implicated in fragile X-associated tremor/ataxia syndrome, fragile X-associated primary ovarian insufficiency, and fragile X syndrome (FXS), respectively. The currently available molecular diagnostic tests are either costly or labour-intensive, which prohibits their application as a first-lineFMR1test in large-scale population-based screening programs. In this study, we demonstrate the utility of a simplified closed-tube strategy for rapid first-line screening of FXS based on melt peak temperature (Tm) analysis of direct triplet-primed polymerase chain reaction amplicons (dTP-PCR MCA). In addition, we also evaluated the correlation betweenTmand CGG-repeat size based on capillary electrophoresis (CE) of dTP-PCR amplicons. The assays were initially tested on 29FMR1reference DNA samples, followed by a blinded validation on 107 previously characterised patient DNA samples. The dTP-PCR MCA produced distinct melt profiles of higherTmfor samples carrying an expanded allele. Among the samples tested, we also observed a good correlation betweenTmand CGG-repeat size. In the blinded validation study, dTP-PCR MCA accurately classified all normal and expansion carriers, and theFMR1genotypic classification of all samples was completely concordant with the previously determined genotypes as well as the dTP-PCR CE results. This simple and cost-effective MCA-based assay may be useful as a first-line FXS screening tool that could rapidly screen out the large majority of unaffected individuals, thus minimising the number of samples that need to be analysed by Southern blot analysis.

CGG repeat expansion at FMR1 locus – A new molecular diagnostic algorithm in fragile X syndrome

2016 ◽  
Vol 64 (6) ◽  
pp. 1138 ◽  
Author(s):  
RavindraKumar Garg ◽  
Neeraj Kumar ◽  
HardeepSingh Malhotra
Keyword(s):  
Fragile X Syndrome ◽  
Fragile X ◽  
Diagnostic Algorithm ◽  
Repeat Expansion ◽  
Molecular Diagnostic ◽  
Cgg Repeat

Variation of the CGG Repeat in FMR-1 Gene in Normal and Fragile X Chinese Subjects

1997 ◽  
Vol 34 (5) ◽  
pp. 517-520 ◽  
Author(s):  
T A Chen ◽  
X F Lu ◽  
P K Che ◽  
Walter K K Ho
Keyword(s):  
Fragile X Syndrome ◽  
Trinucleotide Repeat ◽  
Fragile X ◽  
Cgg Repeat ◽  
Repeat Size ◽  
Cgg Repeats ◽  
Southern Chinese ◽  
The Usa ◽  
Cytological Features ◽  
Repeat Segment

The fragile X syndrome is believed to be caused by an expansion of a CGG trinucleotide repeat segment in the FMR-1 gene on the fragile X site of the long arm of the X-chromosome. To understand the variation of the CGG repeat in the FMR-1 gene in southern Chinese from the Hong Kong and Guangzhou area, we undertook the present study. A total of 83 normal and three fragile X subjects were examined. In the normal group, 16 distinct alleles, ranging in size from 272 bp to 332 bp with 17 to 37 CGG repeats were detected. A repeat size of 29 was the most frequent. Compared with data collected in the USA, the repeat size observed in this population was somewhat smaller. Whether this discrepancy is due to ethnic difference remains to be determined. The three fragile X patients examined in this study did not have a greatly expanded CGG segment. One of them may be a mosaic with one full and one premutation allele. The other two patients, although having clinical and cytological features of fragile X syndrome, had a CGG repeat size within normal range. To explain this, we infer that the mutation in these patients may be caused by other mechanisms, such as other types of FMR-1 mutation or mutation in another site. It is possible that the expansion of the CGG repeats may not be as frequent a cause of fragile X syndrome in southern Chinese as in other ethnic groups.

scholarly journals Fragile X syndrome in Calcutta, India

2001 ◽  
Vol 38 (3) ◽  
pp. 264-271 ◽  
Author(s):  
Sharmila Saha ◽  
Parimal Karmakar ◽  
Chandrahas Chatterjee ◽  
Dalia Banerjee ◽  
Shyamal Das ◽  
...  
Keyword(s):  
Mental Retardation ◽  
Fragile X Syndrome ◽  
Clinical Features ◽  
Untranslated Region ◽  
Fragile X ◽  
Eastern Region ◽  
Ethnic Variation ◽  
Cgg Repeat ◽  
Repeat Size ◽  
Cgg Repeats

Fragile-X-linked mental retardation usually results from amplification of the CGG repeat in the 5' untranslated region of the FMR1 gene. To assess the extent of variation of the CGG repeat in the population from the eastern region of India we studied 98 mentally retarded individuals living in and around Calcutta and identified 21 distinct alleles ranging in size from 8 to 44 CGG repeats. A repeat size of 28 was the most frequent; this value is different from the most frequent repeat size found in other studies, indicating a racial or ethnic variation. Patients with the clinical features of the syndrome have been found to carry expanded CGG repeats. Thus, it can be inferred that the expansion of CGG repeats may be a frequent cause of the syndrome in our population.

scholarly journals Autism Profiles of Males With Fragile X Syndrome

2008 ◽  
Vol 113 (6) ◽  
pp. 427-438 ◽  
Author(s):  
Susan W. Harris ◽  
David Hessl ◽  
Beth Goodlin-Jones ◽  
Jessica Ferranti ◽  
Susan Bacalman ◽  
...  
Keyword(s):  
Fragile X Syndrome ◽  
Fragile X ◽  
Autism Diagnosis ◽  
Cgg Repeat ◽  
Molecular Features ◽  
Fmr1 Mrna ◽  
Two Measures ◽  
Dsm Iv ◽  
Relationship Of ◽  
The Relationship

Abstract Autism, which is common in individuals with fragile X syndrome, is often difficult to diagnose. We compared the diagnostic classifications of two measures for autism diagnosis, the ADOS and the ADI-R, in addition to the DSM-IV-TR in 63 males with this syndrome. Overall, 30% of the subjects met criteria for autistic disorder and 30% met criteria for PDD-NOS. The classifications on the ADOS and DSM-IV-TR were most similar, whereas the ADI-R classified subjects as autistic much more frequently. We further investigated the relationship of both FMRP and FMR1 mRNA to symptoms of autism in this cohort and found no significant relationship between the measures of autism and molecular features, including FMRP, FMR1 mRNA, and CGG repeat number.

scholarly journals ASFMR1splice variant

2018 ◽  
Vol 4 (4) ◽  
pp. e246 ◽  
Author(s):  
Padmaja Vittal ◽  
Shrikant Pandya ◽  
Kevin Sharp ◽  
Elizabeth Berry-Kravis ◽  
Lili Zhou ◽  
...  
Keyword(s):  
Mental Retardation ◽  
Splice Variant ◽  
Messenger Rna ◽  
Clinical Symptoms ◽  
Fragile X ◽  
Cgg Repeat ◽  
Men And Women ◽  
Fragile X Mental Retardation ◽  
Repeat Size ◽  
Ataxia Syndrome

ObjectiveTo explore the association of a splice variant of theantisense fragile X mental retardation 1(ASFMR1) gene, loss offragile X mental retardation 1(FMR1) AGG interspersions andFMR1CGG repeat size with manifestation, and severity of clinical symptoms of fragile X-associated tremor/ataxia syndrome (FXTAS).MethodsPremutation carriers (PMCs) with FXTAS, without FXTAS, and normal controls (NCs) had a neurologic evaluation and collection of skin and blood samples. Expression ofASFMR1transcript/splice variant 2 (ASFMR1-TV2), nonsplicedASFMR1, totalASFMR1, andFMR1messenger RNA were quantified and compared using analysis of variance. Least absolute shrinkage and selection operator (LASSO) logistic regression and receiver operating characteristic analyses were performed.ResultsPremutation men and women both with and without FXTAS had higherASFMR1-TV2 levels compared with NC men and women (n = 135,135,p< 0.0001), andASFMR1-TV2 had good discriminating power for FXTAS compared with NCs but not for FXTAS from PMC. After adjusting for age, loss of AGG, larger CGG repeat size (in men), and elevatedASFMR1-TV2 level (in women) were strongly associated with FXTAS compared with NC and PMC (combined).ConclusionsThis study found elevated levels ofASFMR1-TV2and loss of AGG interruptions in both men and women with FXTAS. Future studies will be needed to determine whether these variables can provide useful diagnostic or predictive information.

Learning-disabled Males With a Fragile X CGG Expansion in the Upper Premutation Size Range

PEDIATRICS ◽  
1996 ◽  
Vol 97 (1) ◽  
pp. 122-126
Author(s):  
Randi J. Hagerman ◽  
Louise W. Staley ◽  
Rebecca O'Conner ◽  
Kellie Lugenbeel ◽  
David Nelson ◽  
...  
Keyword(s):  
Mental Retardation ◽  
Fragile X Syndrome ◽  
Size Range ◽  
Cpg Island ◽  
Fragile X ◽  
Learning Disabled ◽  
Full Mutation ◽  
Cgg Repeat ◽  
Responsible Gene ◽  
Repeat Segment

There is a broad spectrum of clinical involvement in both boys and girls affected by fragile X syndrome. Although this disorder is best known as the most common inherited cause of mental retardation, it also can manifest as learning disabilities in individuals with IQs in the broad range of normal. Boys are usually retarded, and girls are usually learning disabled with fragile X syndrome.1 The responsible gene, fragile X mental retardation 1 (FMR1), was isolated in 1991, and the mutation was found to involve expansion of a trinucleotide (CGG) repeat segment. Individuals with fragile X syndrome have a CGG expansion of more than 200 repeats associated with hypermethylation of both the expansion and an adjacent CpG island (full mutation).2,3

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