scholarly journals Increased Instability of Human CTG Repeat Tracts on Yeast Artificial Chromosomes during Gametogenesis

1999 ◽  
Vol 19 (6) ◽  
pp. 4153-4158 ◽  
Author(s):  
Haim Cohen ◽  
Dorothy D. Sears ◽  
Drora Zenvirth ◽  
Philip Hieter ◽  
Giora Simchen
Keyword(s):  
Genetic Analysis ◽  
Trinucleotide Repeat ◽  
Mitotic Division ◽  
Human Diseases ◽  
Ctg Repeats ◽  
Artificial Chromosomes ◽  
Repeat Tract ◽  
Yeast Artificial Chromosomes ◽  
Dmpk Gene ◽  
Ctg Repeat

ABSTRACT Expansion of trinucleotide repeat tracts has been shown to be associated with numerous human diseases. The mechanism and timing of the expansion events are poorly understood, however. We show that CTG repeats, associated with the human DMPK gene and implanted in two homologous yeast artificial chromosomes (YACs), are very unstable. The instability is 6 to 10 times more pronounced in meiosis than during mitotic division. The influence of meiosis on instability is 4.4 times greater when the second YAC with a repeat tract is not present. Most of the changes we observed in trinucleotide repeat tracts are large contractions of 21 to 50 repeats. The orientation of the insert with the repeats has no effect on the frequency and distribution of the contractions. In our experiments, expansions were found almost exclusively during gametogenesis. Genetic analysis of segregating markers among meiotic progeny excluded unequal crossover as the mechanism for instability. These unique patterns have novel implications for possible mechanisms of repeat instability.

scholarly journals CTG Expansion & Haplotype Analysis in DM1 Gene in Healthy Iranian Population

2008 ◽  
Vol 35 (2) ◽  
pp. 216-219 ◽  
Author(s):  
Bahareh Shojasaffar ◽  
Neda Moradin ◽  
Kimia Kahrizi ◽  
Ana Maria Cobo ◽  
Hossein Najmabadi
Keyword(s):  
Western Europe ◽  
Strong Linkage Disequilibrium ◽  
Healthy Individuals ◽  
Ctg Repeats ◽  
Large Size ◽  
Pcr Rflp ◽  
Ctg Expansion ◽  
Dmpk Gene ◽  
Ctg Repeat

Myotonic dystrophy type 1 (DM1) is due to an unstable expansion of CTG repeat in the DMPK gene (19q13.3). The CTG repeat is highly polymorphic (5 to 37) in healthy individuals. According to the hypothesis that expanded (CTG)n alleles originated from larger normal alleles, there may exist a correlation between the prevalence of DM1 and the frequency of large size normal alleles. Strong linkage disequilibrium between different length alleles and the three biallelic markers, Alu, Hinf1 and Taq1, has been reported.Objective:To determine the distribution of normal alleles, the frequency of larger normal alleles and analysis of the three biallelic markers, in healthy Iranian controls.Material and Methods:Polymerase chain reaction (PCR) was conducted on two hundred unrelated healthy individuals from different ethnic groups living in Iran to determine the size of the alleles. Markers were analyzed by PCR/RFLP on 174 chromosomes from other control healthy individuals.Results:Our data reveals that 23.7% of alleles had 5 CTG repeats and 7.2% of alleles had >18 CTG repeats. The analysis of haplotypes revealed that 75% of CTG5 and 80% of CTG>18 had the (+++) haplotype.Conclusion:The frequency of alleles with CTG>18 in Iran is similar to that of Western Europe and Japan.

scholarly journals Transcriptionally Repressive Chromatin Remodelling and CpG Methylation in the Presence of Expanded CTG-Repeats at the DM1 Locus

2013 ◽  
Vol 2013 ◽  
pp. 1-16 ◽  
Author(s):  
Judith Rixt Brouwer ◽  
Aline Huguet ◽  
Annie Nicole ◽  
Arnold Munnich ◽  
Geneviève Gourdon
Keyword(s):  
Transgenic Mice ◽  
Trinucleotide Repeat ◽  
Cpg Methylation ◽  
Chromatin Remodelling ◽  
Ctcf Binding ◽  
Type I ◽  
Repeat Instability ◽  
Ctg Repeats ◽  
Repressive Chromatin ◽  
Ctg Repeat

An expanded CTG-repeat in the 3′ UTR of theDMPKgene is responsible for myotonic dystrophy type I (DM1). Somatic and intergenerational instability cause the disease to become more severe during life and in subsequent generations. Evidence is accumulating that trinucleotide repeat instability and disease progression involve aberrant chromatin dynamics. We explored the chromatin environment in relation to expanded CTG-repeat tracts in hearts from transgenic mice carrying the DM1 locus with different repeat lengths. Using bisulfite sequencing we detected abundant CpG methylation in the regions flanking the expanded CTG-repeat. CpG methylation was postulated to affect CTCF binding but we found that CTCF binding is not affected by CTG-repeat length in our transgenic mice. We detected significantly decreasedDMPKsense andSIX5transcript expression levels in mice with expanded CTG-repeats. Expression of the DM1 antisense transcript was barely affected by CTG-repeat expansion. In line with altered gene expression, ChIP studies revealed a locally less active chromatin conformation around the expanded CTG-repeat, namely, decreased enrichment of active histone mark H3K9/14Ac and increased H3K9Me3 enrichment (repressive chromatin mark). We also observed binding of PCNA around the repeats, a candidate that could launch chromatin remodelling cascades at expanded repeats, ultimately affecting gene transcription and repeat instability.

scholarly journals Three-dimensional chromatin interactions remain stable upon CAG/CTG repeat expansion

2019 ◽  
Author(s):  
Gustavo A. Ruiz Buendía ◽  
Marion Leleu ◽  
Flavia Marzetta ◽  
Ludovica Vanzan ◽  
Jennifer Y. Tan ◽  
...  
Keyword(s):  
Neurological Disorders ◽  
Three Dimensional ◽  
Repeat Expansion ◽  
Ctcf Binding ◽  
Chromatin Interaction ◽  
Ctg Repeats ◽  
Repeat Tract ◽  
Chromatin Interactions ◽  
Chromatin Folding ◽  
Ctg Repeat

AbstractExpanded CAG/CTG repeats underlie thirteen neurological disorders, including myotonic dystrophy (DM1) and Huntington’s disease (HD). Upon expansion, CAG/CTG repeat loci acquire heterochromatic characteristics. This observation raises the hypothesis that repeat expansion provokes changes to higher order chromatin folding and thereby affects both gene expression in cis and the genetic instability of the repeat tract. Here we tested this hypothesis directly by performing 4C sequencing at the DMPK and HTT loci from DM1 and HD patient-derived cells. Surprisingly, chromatin contacts remain unchanged upon repeat expansion at both loci. This was true for loci with different DNA methylation levels and CTCF binding. Repeat sizes ranging from 15 to 1,700 displayed strikingly similar chromatin interaction profiles. Our findings argue that extensive changes in heterochromatic properties are not enough to alter chromatin folding at expanded CAG/CTG repeat loci. Moreover, the ectopic insertion of an expanded repeat tract did not change three-dimensional chromatin contacts. We conclude that expanded CAG/CTG repeats have little to no effect on chromatin conformation.

scholarly journals Expansion of trinucleotide CTG repeats in the TCF4 gene as a marker of fuchs’ endothelial corneal dystrophy

2019 ◽  
Vol 12 (2) ◽  
pp. 11-18
Author(s):  
Sanasar S. Papanyan ◽  
Sergey Yu. Astakhov ◽  
Vladimir D. Nazarov ◽  
Sergey V. Lapin ◽  
Sergey A. Novikov ◽  
...  
Keyword(s):  
Progressive Disease ◽  
Trinucleotide Repeat ◽  
Corneal Edema ◽  
Corneal Dystrophy ◽  
Triplet Repeat ◽  
Triplet Repeats ◽  
Ctg Repeats ◽  
Laboratory Marker ◽  
The Third ◽  
Ctg Repeat

Fuchs’ endothelial corneal dystrophy (FECD) is an inherited severe and progressive disease, characte­rized by endothelial cell density decrease and increasing corneal edema. FECD development may be linked to expanded trinucleotide repeat, CTG, in the third intron of the TCF4 gene. The study focuses on estimating the prevalence of expanded CTG repeat in TCF4 gene in the Russian population, in patients with normal cornea and in patients with FECD (by applying triplet repeat PCR technique and capillary electrophoresis). 51 patients with FECD and 38 patients with normal cornea were examined. The estimation of the number of CTG triplet repeats in TCF4 gene determination is the veracious laboratory marker of FECD.

Myotonic dystrophy Rossolimo-Churchman-Steinert-Batten (clinical case)

2020 ◽  
pp. 71-72
Author(s):  
И.А. Синельникова ◽  
И.В. Сопрунова ◽  
О.П. Николаева
Keyword(s):  
Case Report ◽  
Myotonic Dystrophy ◽  
Clinical Case ◽  
Molecular Genetic ◽  
Ctg Repeats ◽  
Molecular Genetic Method ◽  
Genetic Method ◽  
Family Case ◽  
Dmpk Gene

В статье представлено описание семейного случая миотонической дистрофии Россолимо-Штейнерта-Куршмана-Баттена. Диагноз подтвержден в результате ДНК-диагностики: выявлено увеличенное число копий CTG-повтора гена DMPK, ответственного за развитие миотонической дистрофии. A family case report of Rossolimo-Steinert-Curschmann myotonic dystrophy is presented. An increased number of copies of CTG-repeats of the DMPK gene responsible for the development of MD, i.e., the diagnosis was confirmed by molecular genetic method.

Murine Albino-Deletion Complex: High-Resolution Microsatellite Map and Genetically Anchored YAC Framework Map

Genetics ◽  
1997 ◽  
Vol 147 (2) ◽  
pp. 787-799
Author(s):  
Brad A Rikke ◽  
Dabney K Johnson ◽  
Thomas E Johnson
Keyword(s):  
Positional Cloning ◽  
Interspecific Backcross ◽  
Genetic Distances ◽  
Sequence Length ◽  
Recombination Rates ◽  
Oak Ridge ◽  
Artificial Chromosomes ◽  
Microsatellite Map ◽  
Specific Locus ◽  
Yeast Artificial Chromosomes

The murine albino-deletion complex developed as part of the Oak Ridge specific-locus test covers 6–11 cM of chromosome 7. This complex has proven to be a valuable resource for localizing traits to a small target region suitable for positional cloning. In this study, we mapped the endpoints of deletions in this complex using all of the available Mit simple-sequence length polymorphism (SSLP) markers. Concurrently, this mapping has determined the map order of nearly all of the SSLP markers, most of which were previously unresolved. The SSLP-based deletion map was confirmed and genetic distances were determined using the European Collaborative Interspecific Backcross panel of nearly a thousand mice. The average SSLP marker resolution is 0.3–0.4 cM, comparable to the cloning capacity of yeast artificial chromosomes (YACs). The SSLP markers were then used to construct a genetically anchored YAC framework map that further confirms the deletion map. We find that the largest deleted region distal to Tyr is about two to three times larger than the largest proximal deleted region, and the original C3H/101 regions flanking the deletions (moved to an St2A cch/cch background) are smaller than anticipated, which we suggest may result from increased recombination rates immediately flanking the deleted regions.

A Novel Ty1-Mediated Fragmentation Method for Native and Artificial Yeast Chromosomes Reveals That the Mouse Steel Gene is a Hotspot for Ty1 Integration

Genetics ◽  
1996 ◽  
Vol 143 (2) ◽  
pp. 673-683
Author(s):  
Jacob Z Dalgaard ◽  
Mukti Banerjee ◽  
M Joan Curcio
Keyword(s):  
Transcription Unit ◽  
Yeast Genome ◽  
Physical Analysis ◽  
Single Chromosome ◽  
Artificial Chromosomes ◽  
Unique Site ◽  
High Fraction ◽  
A Site ◽  
Yeast Artificial Chromosomes ◽  
Random Insertion

Abstract We have developed a powerful new tool for the physical analysis of genomes called Ty1-mediated chromosomal fragmentation and have used the method to map 24 retrotransposon insertions into two different mousederived yeast artificial chromosomes (YACs). Expression of a plasmid-encoded GAL1:Ty1 fusion element marked with the retrotransposition indicator gene, ade2AI, resulted in a high fraction of cells that sustained a single Ty1 insertion marked with ADE2. Strains in which Ty1ADE2 inserted into aYAC were identified by cosegregation of the ADE2 gene with the URA3-marked YAC. Ty1ADE2 elements also carried a site for the endonuclease I-DmoI, which we demonstrate is not present anywhere in the yeast genome. Consequently, I-DmoI cleaved a single chromosome or YAC at the unique site of Ty1ADE2 insertion, allowing rapid mapping of integration events. Our analyses showed that the frequency of Ty1ADE2 integration into YACs is equivalent to or higher than that expected based on random insertion. Remarkably, the 50-kb transcription unit of the mouse Steel locus was shown to be a highly significant hotspot for Ty1 integration. The accessibility of mammalian transcription units to Ty1 insertion stands in contrast to that of yeast transcription units.

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