scholarly journals A Homogeneous Assay for Analysis of FMR1 Promoter Methylation in Patients with Fragile X Syndrome

2007 ◽  
Vol 53 (4) ◽  
pp. 790-793 ◽  
Author(s):  
Christina Dahl ◽  
Karen Grønskov ◽  
Lars A Larsen ◽  
Per Guldberg ◽  
Karen Brøndum-Nielsen
Keyword(s):  
Fragile X Syndrome ◽  
Southern Blot ◽  
Cpg Island ◽  
Fragile X ◽  
Methylation Status ◽  
Melting Peak ◽  
Melting Curve Analysis ◽  
Full Mutation ◽  
Cgg Repeat ◽  
Male Patients

Abstract Background: Fragile X syndrome is caused by the expansion of a CGG trinucleotide repeat at the 5′ untranslated region of the fragile X mental retardation 1 gene (FMR1). When expanded to >200 repeats (full mutation), the repeat region and the adjacent promoter CpG island become hypermethylated, rendering FMR1 transcriptionally inactive. Conventional molecular diagnosis of fragile X syndrome involves determination of the CGG repeat number by Southern blot analysis. Methods: A homogeneous methylation-specific melting curve analysis (MS-MCA) assay for methylation status of the FMR1 promoter region was developed on the LightCycler platform. Genomic DNA was treated with sodium bisulfite, and a region containing 8 CpG sites was amplified in the presence of SYBR Green I, using primers that do not differentiate between methylated and unmethylated FMR1 molecules. After amplification, the samples were melted at 0.05 °C/s, and fluorescence melting curves were recorded. We studied samples, previously characterized by Southern blot analyses, from 10 female and 10 male donors with normal numbers of CGG trinucleotide repeats, 9 male donors who were premutation carriers, 4 male donors who carried both a premutation and a full mutation, and 25 patients with fragile X syndrome. Results: Samples from all 20 male patients with fragile X syndrome showed a high melting peak corresponding to fully methylated FMR1, whereas samples from healthy males showed a single low melting peak corresponding to unmethylated FMR1. Of 24 samples from affected males, 9 (38%) showed 2 melting peaks, suggesting that cellular methylation mosaicism is common in fragile X syndrome. Conclusions: MS-MCA allows rapid and reliable identification of fragile X syndrome in male patients.

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

scholarly journals Cascade Testing for Fragile X Syndrome in a Rural Setting in Cameroon (Sub-Saharan Africa)

Genes ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 136
Author(s):  
Karen Kengne Kamga ◽  
Séraphin Nguefack ◽  
Khuthala Minka ◽  
Edmond Wonkam Tingang ◽  
Alina Esterhuizen ◽  
...  
Keyword(s):  
Fragile X Syndrome ◽  
Fragile X ◽  
Autism Spectrum ◽  
Sub Saharan Africa ◽  
Rural Setting ◽  
Premature Menopause ◽  
Molecular Testing ◽  
Full Mutation ◽  
Cgg Repeat ◽  
Cgg Repeats

Fragile X Syndrome (FXS), an X-linked dominant monogenic condition, is the main genetic cause of intellectual disability (ID) and autism spectrum disorder (ASD). FXS is associated with an expansion of CGG repeat sequence in the Fragile X Mental Retardation gene 1 (FMR1) on chromosome X. Following a neuropediatric assessment of two male siblings who presented with signs of FXS that was confirmed with molecular testing, we provided cascade counselling and testing to the extended family. A total of 46 individuals were tested for FXS; among them, 58.70% (n = 27) were females. The mean age was 9.4 (±5) years for children and 45.9 (±15.9) years for adults. Pedigree analysis suggested that the founder of these families was likely a normal transmitting male. Four out of 19 males with clinical ID were confirmed to have a full mutation for FXS, while 14/27 females had a pathologic CGG expansion (>56 CGG repeats) on one of their X chromosomes. Two women with premature menopause were confirmed of being carriers of premutation (91 and 101 CGG repeats). We also identified maternal alleles (91 and 126 CGG repeats) which expanded to a full mutation in their offspring (>200 CGG repeats). This study is a rare report on FXS from Africa and illustrates the case scenario of implementing genetic medicine for a neurogenetic condition in a rural setting.

A Novel Polymorphism in the FMR1 Gene: Implications for Clinical Testing of Fragile X Syndrome

2008 ◽  
Vol 132 (1) ◽  
pp. 95-98
Author(s):  
Bharat Thyagarajan ◽  
Matthew Bower ◽  
Michael Berger ◽  
Sidney Jones ◽  
Michelle Dolan ◽  
...  
Keyword(s):  
Polymerase Chain Reaction ◽  
Mental Retardation ◽  
Fragile X Syndrome ◽  
Southern Blot ◽  
Trinucleotide Repeat ◽  
Fragile X ◽  
Fmr1 Gene ◽  
Chain Reaction ◽  
Cgg Repeat ◽  
Polymerase Chain

Abstract Fragile X syndrome is the most common cause of inherited mental retardation among males. In most cases, the molecular basis of fragile X syndrome is the expansion and subsequent methylation of a CGG trinucleotide repeat in the 5′ untranslated region of the fragile X mental retardation 1 (FMR1) gene. Laboratory diagnosis usually relies on a combination of Southern blot and polymerase chain reaction analyses. In this case report we describe an unusual Southern blot result in a patient who presented with developmental delay and had a normal CGG repeat number by polymerase chain reaction analysis. Further investigation revealed a novel G3310C transversion in the FMR1 gene resulting in a new recognition site for the BssHII restriction enzyme. This novel restriction site could potentially mimic a partial deletion of the FMR1 gene on Southern blot analysis and thus represents a possible pitfall in the diagnosis of fragile X syndrome.

scholarly journals Reversion to Normal of FMR1 Expanded Alleles: A Rare Event in Two Independent Fragile X Syndrome Families

Genes ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 248
Author(s):  
Elisabetta Tabolacci ◽  
Roberta Pietrobono ◽  
Giulia Maneri ◽  
Laura Remondini ◽  
Veronica Nobile ◽  
...  
Keyword(s):  
Fragile X Syndrome ◽  
Binding Sites ◽  
Molecular Mechanisms ◽  
Fragile X ◽  
Rare Event ◽  
The Other ◽  
Fmr1 Gene ◽  
Full Mutation ◽  
Cgg Repeat ◽  
Agg Interruptions

Fragile X syndrome (FXS) is mostly due to the expansion and subsequent methylation of a polymorphic CGG repeat in the 5’ UTR of the FMR1 gene. Full mutation alleles (FM) have more than 200 repeats and result in FMR1 gene silencing and FXS. FMs arise from maternal premutations (PM) that have 56–200 CGGs; contractions of a maternal PM or FM are rare. Here, we describe two unaffected boys in two independent FXS families who inherited a non-mosaic allele in the normal and intermediate range, respectively, from their mothers who are carriers of an expanded CGG allele. The first boy inherited a 51 CGG allele (without AGG interruptions) from his mother, who carries a PM allele with 72 CGGs. The other boy inherited from his FM mother an unusual allele with 19 CGGs resulting from a deletion, removing 85 bp upstream of the CGG repeat. Given that transcription of the deleted allele was found to be preserved, we assume that the binding sites for FMR1 transcription factors are excluded from the deletion. Such unusual cases resulting in non-mosaic reduction of maternal CGG expansions may help to clarify the molecular mechanisms underlying the instability of the FMR1 gene.

scholarly journals Mosaicism for the fragile X syndrome full mutation and deletions within the CGG repeat of the FMR1 gene.

1996 ◽  
Vol 33 (4) ◽  
pp. 338-340 ◽  
Author(s):  
M Mila ◽  
S Castellvi-Bel ◽  
A Sanchez ◽  
C Lazaro ◽  
M Villa ◽  
...  
Keyword(s):  
Fragile X Syndrome ◽  
Fragile X ◽  
Fmr1 Gene ◽  
Full Mutation ◽  
Cgg Repeat

scholarly journals A Novel FMR1 PCR Method for the Routine Detection of Low Abundance Expanded Alleles and Full Mutations in Fragile X Syndrome

2010 ◽  
Vol 56 (3) ◽  
pp. 399-408 ◽  
Author(s):  
Stela Filipovic-Sadic ◽  
Sachin Sah ◽  
Liangjing Chen ◽  
Julie Krosting ◽  
Edward Sekinger ◽  
...  
Keyword(s):  
Fragile X Syndrome ◽  
Southern Blotting ◽  
Trinucleotide Repeat ◽  
Fragile X ◽  
Clinical Samples ◽  
Full Mutation ◽  
Cgg Repeat ◽  
Specific Pcr ◽  
Cgg Repeats ◽  
Pcr Technology

Abstract Background: Fragile X syndrome (FXS) is a trinucleotide-repeat disease caused by the expansion of CGG sequences in the 5′ untranslated region of the FMR1 (fragile X mental retardation 1) gene. Molecular diagnoses of FXS and other emerging FMR1 disorders typically rely on 2 tests, PCR and Southern blotting; however, performance or throughput limitations of these methods currently constrain routine testing. Methods: We evaluated a novel FMR1 gene–specific PCR technology with DNA templates from 20 cell lines and 146 blinded clinical samples. The CGG repeat number was determined by fragment sizing of PCR amplicons with capillary electrophoresis, and results were compared with those for FMR1 Southern blotting analyses with the same samples. Results: The FMR1 PCR accurately detected full-mutation alleles up to at least 1300 CGG repeats and consisting of >99% GC character. All categories of alleles detected by Southern blotting, including 66 samples with full mutations, were also identified by the FMR1 PCR for each of the 146 clinical samples. Because all full mutation alleles in samples from heterozygous females were detected by the PCR, allele zygosity was reconciled in every case. The PCR reagents also detected a 1% mass fraction of a 940-CGG allele in a background of 99% 23-CGG allele—a roughly 5- fold greater sensitivity than obtained with Southern blotting. Conclusions: The novel PCR technology can accurately categorize the spectrum of FMR1 alleles, including alleles previously considered too large to amplify; reproducibly detect low abundance full mutation alleles; and correctly infer homozygosity in female samples, thus greatly reducing the need for sample reflexing to Southern blotting.

scholarly journals FMR1 gene mutations in patients with fragile X syndrome and obligate carriers: 30 years of experience in Chile

2016 ◽  
Vol 98 ◽  
Author(s):  
LORENA SANTA MARÍA ◽  
SOLANGE ALIAGA ◽  
VÍCTOR FAUNDES ◽  
PAULINA MORALES ◽  
ÁNGELA PUGIN ◽  
...  
Keyword(s):  
Fragile X Syndrome ◽  
Southern Blot ◽  
Fragile X ◽  
Gene Mutations ◽  
Molecular Technique ◽  
Grey Zone ◽  
Cascade Screening ◽  
Cgg Repeat ◽  
Cgg Repeats ◽  
Age Of Diagnosis

SummaryFragile X syndrome (FXS) is the most common form of inherited intellectual disability (ID) and co-morbid autism. It is caused by an amplification of the CGG repeat (>200), which is known as the full mutation, within the 5′UTR of the FMR1 gene. Expansions between 55–200 CGG repeats are termed premutation and are associated with a greater risk for fragile X-associated tremor/ataxia syndrome and fragile X-associated premature ovarian insufficiency. Intermediate alleles, also called the grey zone, include approximately 45–54 repeats and are considered borderline. Individuals with less than 45 repeats have a normal FMR1 gene. We report the occurrence of CGG expansions of the FMR1 gene in Chile among patients with ID and families with a known history of FXS. Here, we present a retrospective review conducted on 2321 cases (2202 probands and 119 relatives) referred for FXS diagnosis and cascade screening at the Institute of Nutrition and Food Technology (INTA), University of Chile. Samples were analysed using traditional cytogenetic methods and/or PCR. Southern blot was used to confirm the diagnosis. Overall frequency of FMR1 expansions observed among probands was 194 (8·8%), the average age of diagnosis was 8·8 ± 5·4 years. Of 119 family members studied, 72 (60%) were diagnosed with a CGG expansion. Our results indicated that the prevalence of CGG expansions of the FMR1 gene among probands is relatively higher than other populations. The average age of diagnosis is also higher than reference values. PCR and Southern blot represent a reliable molecular technique in the diagnosis of FXS.

FMR1 Linked haplotype analysis in a mentally retarded male population

Open Medicine ◽  
2011 ◽  
Vol 6 (6) ◽  
pp. 750-757
Author(s):  
Zanda Daneberga ◽  
Natalija Pronina ◽  
Baiba Lace ◽  
Rita Lugovska
Keyword(s):  
Cpg Island ◽  
Fragile X ◽  
Control Group ◽  
Grey Zone ◽  
Male Population ◽  
Control Male ◽  
Cgg Repeat ◽  
Cgg Repeats ◽  
Male Patients ◽  
The Baltic

AbstractFragile X syndrome is caused by dynamic mutation of FMR1 gene CpG island CGG repeats. The underlying mutational mechanism is not fully understood. Different microsatellite markers and SNP have previously been reported as markers associated with FMR1 CGG repeat instability. The aim of the present study was to identify specific haplotypes among Latvian FXS patients and the control group with respect to allelic stability. Eleven male FXS patients and 122 control male patients participated in the study. In total, 27 different DXS548-FRAXAC1-ATL1-FRAXAC2 haplotypes were found. The prevalent haplotype in the control group was 7-4-A-5+ (rel. frequency 0.327). The prevalent haplotype associated with the FXS group was 2-2-G-4 (rel. frequency 0.818; p < 0.0001). Grey zone alleles with a long uninterrupted CGG tract at the 3’ end were significantly associated with the 2-2-G-4 haplotype (p = 0.0022). Our findings suggest that, for the Latvian population, the haplotype 2-2-G-4 is a marker of CGG tract instability. We conclude that a founder effect could not be an explanation for our findings on the basis of heterogeneity exhibited by the Latvian population and lack of studies throughout this geographical region. This data may provide evidence of different mutational pathways of expansion in the Baltic States region.

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.

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