Alleles trinucleotide repeat expansion. Medical search. Frequent questions

Friedreich's ataxia is thus believed to be a mitochondrial disease caused by a mutation in the nuclear genome (specifically, expansion of an intronic GAA triplet repeat in the FXN gene, which encodes the protein frataxin. (wikipedia.org)
The reduction in frataxin gene expression may be attributable from either the silencing of transcription of the frataxin gene because of epigenetic modifications in the chromosomal entity or from the inability of splicing the expanded GAA repeats in the first intron of the pre-mRNA as seen in bacteria and Human cells or both. (wikipedia.org)
96% of FRDA patients have a GAA trinucleotide repeat expansion in intron 1 of both alleles of their FXN gene. (wikipedia.org)
Another approach involves inserting a GAA expansion into the first intron of the mouse FXN gene, which should inhibit frataxin production, just like in humans. (wikipedia.org)
FA is an autosomal recessive disorder caused by a mutation and abnormal expansion of a GAA repeat in intron 1 of the FXN gene, which is located on chromosome 9. (medscape.com)
Approximately 98% of mutant alleles have an expansion of a gossypol acetic acid (GAA) trinucleotide repeat in intron 1 of the gene, leading to reduced levels of frataxin. (medscape.com)
Single-nucleotide polymorphism rs3849942 is associated with ALS, tagging a hexanucleotide repeat mutation in the C9orf72 gene. (ox.ac.uk)
Friedreich's ataxia (FA) is an autosomal recessive condition caused by a GAA trinucleotide repeat expansion in the X25 gene on chromosome 9. (bmj.com)
DNA analysis of the FRATAXIN gene in the patient showed that the GAA expansion was present in one allele but not the other, while her mother was negative for the GAA expansion in both alleles. (bmj.com)
The underlying defect is a GAA trinucleotide repeat expansion in the X25 gene on chromosome 9 with 90% of those studied being homozygous for expanded alleles and over half of the remaining patients being compound heterozygotes, carrying one allele with a repeat expansion and the other with a point mutation. (bmj.com)
Fragile X is usually caused by a trinucleotide expansion in the FMR1 gene on the X chromosome. (uab.edu)
If a homozygous female, premutation, or full mutation is identified or suspected, a second tier of testing consists of Eco RI and Eag I restriction digest followed by Southern blot analysis using the DNA probe, StB12.3 to determine methylation status of the FMR1 gene and approximate number of trinucleotide repeats. (uab.edu)
Is the 31 CAG repeat allele of the spinocerebellar ataxia 1 (SCA1) gene locus non-specifically associated with trinucleotide expansion diseases? (cdc.gov)
Huntington's disease (HD) is a progressive and fatal neurodegenerative disorder caused by an expanded CAG repeat in the huntingtin gene. (nature.com)
The mutation on the FMR1 gene is called a trinucleotide repeat expansion , which is a sequence of three DNA nucleotides that is repeated many times. (sharinghealthygenes.com)
Large alleles are unstable, or "fragile," and so the number of repeats can change as the gene is passed from generation to generation. (sharinghealthygenes.com)
REVIEW-ARTICLE Intermediate alleles of Huntington's disease HTT gene in different populations worldwide: a systematic review. (geneticsmr.com)
Huntington's disease (HD) is an autosomal dominant progressive neurodegenerative disorder caused by a dynamic mutation due to the expansion of CAG repeats in the HTT gene (4p16.3). (geneticsmr.com)
If expression of a trait requires only one copy of a gene (one allele). (msdmanuals.com)
Type 1 DM (DM1) involves expansion of a CTG trinucleotide repeat of the DMPK gene located on chromosome 19. (msdmanuals.com)
Type 2 DM (DM2) is milder and involves a CCTG repeat expansion mutation of the cellular nucleic acid binding protein gene CNBP (previously known as ZFN9) on chromosome 3q21.3. (msdmanuals.com)
Huntington Disease (HD) is a hereditary neurological disorder that shows a gene expansion associated with trinucleotide repeats. (medicalalgorithms.com)
Carrier screening is a term used to describe genetic testing that is performed on an individual who does not have any overt phenotype for a genetic disorder but may have one variant allele within a gene(s) associated with a diagnosis. (acog.org)
Huntington disease (HD) is caused by an expansion of cytosine-adenine-guanine (CAG) trinucleotide repeats within the HTT gene. (arupconsult.com)
Polymerase chain reaction (PCR) testing and size analysis for an expanded number of cytosine-adenine-guanine (CAG) trinucleotide repeats in the HTT gene may be performed for both symptomatic individuals and asymptomatic individuals with a family history of HD. (arupconsult.com)
For instance, if you've got a mutation caused by triplet repeat expansion, for instance in the Huntington's gene, where the trinucleotide repeats a CAG, you might have 17 CAGs in a normal chromosome. (hstalks.com)
But in a diseased chromosome, you might have 40 successive copies of CAG trinucleotides in the gene. (hstalks.com)
The huntingtin gene encodes a protein of 350 kD;the disease causing mutation is an expansion of an amino-terminal polyglutamine repeat of more than 36 successive glutamines. (grantome.com)
Because HD is an inherited disease, we expected that the mutant allele will differ from wild-type by at least a single nucleotide polymorphism, thereby offering a target for gene silencing by RNAi. (grantome.com)
Common single nucleotide polymorphisms (SNPs) and a trinucleotide repeat polymorphism, thymine-guanine-cytosine (TGC), in the TCF4 gene have been associated with the risk of FECD in some populations. (edu.au)
HTT is the gene implicated in HD and contains a normally polymorphic trinucleotide CAG repeat region in the first exon. (upmc.com)
Individuals with a CAG repeat size of 30 to 35 do not manifest Huntington's Disease themselves, however, the risk that their offspring will develop HD may be increased, particularly from paternal transmission of the gene. (upmc.com)
Detection of CAG expansions in the HTT gene that lead to Huntington's Disease. (upmc.com)
Determination of an expanded trinucleotide CAG repeat region is based on PCR amplification of the Huntingtin (HTT) gene using a pair of primers specific for the surrounding region. (upmc.com)
A Novel Gene Containing a Trinucleotide Repeat That is Expanded and Unstable on Huntington's Disease Chromosomes. (upmc.com)
The CGG trinucleotide repeat within the FMR1 gene is associated with multiple clinical disorders, including fragile X-associated tremor/ataxia syndrome, fragile X-associated primary ovarian insufficiency, and fragile X syndrome. (irdrjournal.com)
Huntington's Disease (HD) is a neurodegenerative disease, caused by the expansion of an unstable (CAG) n in the HTT gene. (siu.edu.ar)
One individual was found to carry a 12 kb deletion in one copy of the ASPA gene on 17p13, which when mutated in both alleles leads to Canavan disease. (biomedcentral.com)
Individuals with juvenile onset usually have over 55 repeats, and they usually inherit the gene from their father. (jci.org)
Individuals with one dominant allele for a disorder (described as being heterozygous for the gene) will express disease and trans-mit the gene to 50% of their offspring (Box 7.1). (brainkart.com)

A subset of FRDA patients have GAA expansion in one chromosome and a point mutation in the FXN exon in the other chromosome. (wikipedia.org)
Although nearly all organisms express a frataxin homologue, the GAA repeat in intron 1 only exists in humans and other primates, so the mutation that causes FDRA can't occur naturally in other animals. (wikipedia.org)
These results indicate residual association at the C9orf72 locus suggesting a second disease-causing repeat mutation. (ox.ac.uk)
Individuals with pre-mutation alleles have 59-230 repeats whereas individuals with intermediate sized alleles ("gray zone" alleles) have 41-58 repeats, broadly defined. (uab.edu)
In this way, some carriers of the FMR1 mutation can have no symptoms, but if the repeat size of their mutation increases to a critical point when passed to their child, then the child may be symptomatic. (sharinghealthygenes.com)
Many alleles of this size are unstable and can expand to a full mutation. (sharinghealthygenes.com)
Carriers of a full mutation allele can have an affected child. (sharinghealthygenes.com)
Also, about half of female carriers of a full mutation allele have symptoms of fragile X syndrome and are considered to be affected. (sharinghealthygenes.com)
Female carriers of full mutation alleles are not at an increased risk of POI. (sharinghealthygenes.com)
2) lilli mutation strongly suppresses the rough eye phenotype of ectopically expressed phyllopod (Tang, 2001), and (3) lilli was identified in a screen for genes that enhance the embryonic lethal phenotype of dpp alleles (Su, 2001). (sdbonline.org)
Indeed, mutation detection enhancement gel electrophoresis of mixed PCR products from cloned haplotypes revealed 24 distinct heteroduplex patterns for the six possible trinucleotide heterozygotes. (scite.ai)
An example of a genetic mutation that shows anticipation is Huntington disease, where an expansion of the trinucleo-tide repeat, CAG, leads to earlier expression of the disease in affected offspring. (brainkart.com)

Trinucleotide repeats are a source of genome instability, causing replication fork stalling, chromosome fragility, and impaired repair. (tufts.edu)
HD arises from a CAG trinucleotide repeat expansion on chromosome 4 . (sketchy.com)
2006). A novel trinucleotide repeat expansion at chromosome 3q26.2 identified by a CAG/CTG repeat expansion detection array . (up.pt)

Short tandem repeats (STRs), or microsatellites, are 1-6 base pair (bp) motifs of repeating units of DNA. (biomedcentral.com)
Long expansions of transcribed trinucleotide microsatellites have been etiologically associated with some neurological diseases. (scite.ai)
Today I'm going to tell you about microsatellites, and trinucleotide repeat expansions diseases. (hstalks.com)
Short tandem repeats (STRs), also known as microsatellites, are repetitive DNA sequences consisting of 1-6-bp motifs present in a genome. (researchsquare.com)

lilli mutations disrupt the transvection-dependent dpp phenotype and are also dominant maternal enhancers of recessive embryonic lethal alleles of dpp and screw . (sdbonline.org)

Individuals with intermediate alleles (27-35 cytosine-adenine-guanine [CAG] repeats) typically do not have symptoms of Huntington disease (HD). (arupconsult.com)

Huntington's disease (HD) is the most prevalent autosomal dominant, trinucleotide repeat neurodegenerative disease. (grantome.com)

So, children of carriers of intermediate alleles are not at risk of fragile X syndrome. (sharinghealthygenes.com)
Carriers of intermediate alleles are not expected to have any health problems related to their fragile X syndrome carrier status. (sharinghealthygenes.com)
Intermediate alleles (IAs) show 27 to 35 CAG repeats and expanded alleles have more than 35 repeats. (geneticsmr.com)
Those with intermediate alleles are prone to this repeat instability and may have children with an HD-causing allele. (arupconsult.com)

The expansions were identified in whole-genome datasets within genomic segments that all affected family members shared. (lu.se)
Short tandem repeats (STRs) compose approximately 3% of the genome, and mutations at STR loci have been linked to dozens of human diseases including amyotrophic lateral sclerosis, Friedreich ataxia, Huntington disease, and fragile X syndrome. (biomedcentral.com)
Some of these tools are designed to detect STR expansions at disease-related loci, while others detect expansions and contractions of STRs genome-wide but are constrained by sequencing read length and the STR motif size. (biomedcentral.com)
Several groups have reported association between large CAG/CTG repeat sequences in the genome and bipolar disorder using the Repeat Expansion Detection (RED) method. (cardiff.ac.uk)
Short tandem repeats (STRs) are widely present in the human genome. (researchsquare.com)
Using the allele frequency spectrum of SNVs from 71,702 whole genome sequences in gnomAD, we find that SNVs introducing new stop codons, or creating stronger translation termination signals in uORFs are under strong selective constraints within 5′UTRs. (nature.com)

These highly individual-specific number of repeats and the abundance of motifs have contributed to the polymorphism of STR loci. (researchsquare.com)
The aim of this study was to determine whether TGC repeat polymorphism in TCF4 is associated with FECD in the Australian population. (edu.au)
In 189 unrelated Australian cases with advanced late-onset FECD and 183 matched controls, the TGC repeat polymorphism located in intron 3 of TCF4 was genotyped using a short tandem repeat (STR) assay. (edu.au)

Those with a risk allele of rs903603 had an excess of apparent homozygosity for wild type repeat alleles, consistent with polymerase chain reaction failure of 1 allele because of massive repeat expansion. (ox.ac.uk)
Polymerase chain reaction analysis is used as a first tier test to define the repeat size. (uab.edu)
Polymerase chain reaction analysis is used to further define the repeat number more precisely. (uab.edu)
Sequencing of their polymerase chain reaction (PCR) products revealed a G-->A transition immediately preceding the trinucleotide repeats, hence defining 8 distinct haplotypes and 36 possible genotypes. (scite.ai)

The prevalence of fragile X syndrome and FMR1 associated disorders in various populations is thought to be affected by the total length of the CGG repeat and may also be influenced by the AGG distribution pattern. (irdrjournal.com)

The objective of the present study was to assess ApoE allele and genotype distribution in a large elderly community-based sample and its association with age, sex and skin color. (scite.ai)
No association between number of ApoE4 alleles and age was found, suggesting the absence of association of ApoE genotype with mortality in this population. (scite.ai)

Individuals with expanded repeats developed balance and gait disturbances at 15 to 60. (lu.se)
Individuals with expanded repeats developed balance and gait disturbances at 15 to 60 years of age and had sensory neuropathy and slow saccades. (lu.se)
The number of repeat units differs between individuals, resulting in highly complex allele polymorphisms. (researchsquare.com)
Normal individuals have between 6 and 35 copies of this repeat. (upmc.com)
Affected individuals have an expanded repeat region, usually 36 to 121 copies of the repeat. (upmc.com)
In unaffected individuals, there are 10-34 CAG repeats. (jci.org)

order SCAP / Spinocerebellar Ataxia Repeat Expansion Panel, Varies. (mayocliniclabs.com)
2017). A Pentanucleotide ATTTC Repeat Insertion in the Non-coding Region of DAB1, Mapping to SCA37, Causes Spinocerebellar Ataxia . (up.pt)

DNA analysis showed he was homozygous for the FA repeat expansion. (bmj.com)
The repeat length was verified by direct sequencing in selected homozygous carriers. (edu.au)
Genotypic analysis showed that 51% of cases (97) compared to 5% of controls (9) were heterozygous or homozygous for the expanded repeat allele. (edu.au)

A higher number of CAG repeats is associated with an earlier age of onset. (arupconsult.com)
The number of repeats determines the risk and likely age of onset for symptom development. (arupconsult.com)
The age of onset of the disease varies inversely with the number of CAG repeats. (jci.org)

The penetrance of the CAG expansion is not complete, therefore showing variability in the severity of disease symptoms. (upmc.com)

Exon 1 contains a CAG trinucleotide repeat that encodes the amino acid glutamine, followed by another repeat that encodes proline. (jci.org)

Innovations include targeting mRNA alleles for RNAi, use of HD mouse models that express only human huntingtin genes, quantitative measurement of huntingtin allelic mRNA based on SNP heterozygosities, deep sequencing analysis to identify 3 UTR huntingtin mRNA regulation, and zinc finger nuclease strategy to eliminate huntingtin alleles at the genomic level. (grantome.com)
This assay will not detect certain types of genomic alterations which may cause disease such as, but not limited to, translocations or inversions, repeat expansions (eg. (fulgentgenetics.com)

We used logistic regression to analyze the impact of different repeat expansion genes on dystonia in SCAs. (nih.gov)
Complex genetic interactions among repeat expansion genes can lead to diverse clinical symptoms and progression in SCAs. (nih.gov)
At each locus, there are two possible variations of the genes, or two alleles. (brainkart.com)

The expansion of intronic trinucleotide repeat GAA results in Friedreich's ataxia. (wikipedia.org)
trinucleotides or hexanucleotides), alterations in most regulatory regions (promoter regions) or deep intronic regions (greater than 20bp from an exon). (fulgentgenetics.com)

These data suggest that the previous associations between bipolar disorder and large CAG/CTG repeats might be explained at least in part by a specific association between bipolar disorder and either or both of these loci. (cardiff.ac.uk)

Non-expanded alleles carried one or more interruptions within the repeat. (lu.se)
Frequencies of longer alleles, longer uninterrupted CGG repeat segments and alleles with greater than 2 AGG interruptions varied between cohorts. (irdrjournal.com)

Offspring of patients with FA all inherit one mutant allele from the affected parent. (medscape.com)

As the expansion continues to grow from one generation to the next, symptoms can become more and more severe. (sharinghealthygenes.com)

Carriers of a premutation allele can have a child with fragile X syndrome, although this risk depends on their specific allele size. (sharinghealthygenes.com)
As such, premutation allele carriers are at risk of infertility due to POI. (sharinghealthygenes.com)

Independently of PCNA binding, Srs2 also displaces Rad51 from nascent strands to prevent recombination-dependent repeat expansions and contractions. (tufts.edu)

Some alleles in this category are unstable and can become larger when passed to a child. (sharinghealthygenes.com)
Alleles of this size are unstable. (sharinghealthygenes.com)

These populations originated from a common ancestor, and a rapid demographic expansion began approximately 90,000 years ago. (biomedcentral.com)
Differences in the distribution and prevalence of CGG repeat length and of AGG interruption patterns have been reported among different populations and ethnicities. (irdrjournal.com)

In the typical case, the length of the allele with the shorter GAA expansion inversely correlates with frataxin levels. (wikipedia.org)
3 Expanded alleles are thought to result in low or absent frataxin levels while point mutations cause single amino acid changes in the C terminal region of the frataxin protein, possibly resulting in a loss of function. (bmj.com)

The Srs2 helicase unwinds DNA hairpins, facilitates replication, and prevents repeat instability and fragility. (tufts.edu)
2005). Haplotype diversity and somatic instability in normal and expanded SCA8 alleles . (up.pt)

Notably, paternal inheritance usually results in more severe disease outcomes due to higher CAG expansion during spermatogenesis. (sketchy.com)

We found that an increase in the A16â A24 trinucleotide repeat was accompanied by a gradual decrease in the global distribution of GP60 alleles, strongly suggesting that IIaA16G1R1 represents the primordial allelic variant of this group. (bvsalud.org)
Although next generation sequencing technologies and our bioinformatics analysis significantly reduce the contribution of pseudogene sequences or other highly-homologous sequences, these may still occasionally interfere with the technical ability of the assay to identify pathogenic variant alleles in both sequencing and deletion/duplication analyses. (fulgentgenetics.com)

DNA segments with these repeats are called alleles. (sharinghealthygenes.com)

Anticipation was observed in all families and correlated with different repeat lengths determined through long-read sequencing in two family members. (lu.se)
HD also displays anticipation , a phenomenon where subsequent generations manifest the disease at an earlier age and with increased severity due to the expansion of the trinucleotide repeat. (sketchy.com)

This analysis also includes an examination of C9orf72 repeat expansions by repeat-primed PCR (rpPCR) but does not include C9orf72 methylation studies. (tesiscolorado.com)

The CAG repeat number in TBP normal alleles appeared to modify the presence of dystonia in SCA1. (nih.gov)
The considered normal alleles have less than 27 CAG repeats. (geneticsmr.com)

We searched the expressed sequence tag databank for reiterated trinucleotides and selected EST00493 (D2S196E) with 14 tandem ACA triplets as a potentially polymorphic locus. (scite.ai)

However, large expansions of the CAG repeat region can occur during sperm formation. (arupconsult.com)

Perfect repeats mutate about 2 × more often than imperfect repeats. (biomedcentral.com)

scolymus) has been used to catalog the genome's content of simple sequence repeat (SSR) markers. (researchgate.net)
Diversity and genetic stability in banana genotypes in a breeding program using inter simple sequence repeats (ISSR) markers. (geneticsmr.com)

The decision to rescreen a patient should be undertaken only with the guidance of a genetics professional who can best assess the incremental benefit of repeat testing for additional mutations. (acog.org)

On the other hand, the ε2 allele carriers had lower LDL cholesterol levels (P (scite.ai)

A total of nine GP60 subtypes (IIaAxxG1R1, xx = 16 to 24) were identified, showing a stepwise increase of the trinucleotide motif TCA, and including the zoonotic subtypes IIaA16G1R1, IIaA17G1R1, IIaA18G1R1, IIaA19G1R1, and IIaA20G1R1. (bvsalud.org)

50 repeat units and cause Fuchs endothelial corneal dystrophy. (nih.gov)
The TCF4 Trinucleotide Repeat Expansion of Fuchs' Endothelial Corneal Dystrophy: Implications for the Anterior Segment of the Eye. (nih.gov)

93-28.25), showing that the African-Brazilian elderly have a high prevalence of the ε4 allele, as observed in blacks from Africa. (scite.ai)

Here, we report the discovery of exonic GGC trinucleotide repeat expansions, encoding poly-glycine, in zinc finger homeobox 3 (ZFHX3) in these families. (lu.se)

We will use a new strategy to quantify each huntingtin allelic mRNA, based on SNP heterozygosities of the alleles. (grantome.com)

Furthermore, the repeat expansion showed stronger association than the most significantly associated SNP, rs613872, in TCF4 , with the disease in the Australian cohort. (edu.au)

Analysis was carried out taking into consideration the six ApoE genotypes (ε3/ ε3, ε3/ε4, ε2/ε3, ε4/ε4, ε2/ε4, and ε2/ε2), the three ApoE alleles, and the number of ApoE4 alleles for each individual. (scite.ai)

Similarly the effect of expressing a dominant negative Cyclin-dependent kinase 9 allele was analyzed. (sdbonline.org)

Unfortunately, the RED method cannot identify the specific repeat(s) responsible for these findings but it has recently been proposed that around 90% of the large CAG/CTG repeats detected by RED can be explained by repeat size at either CTG18.1, which maps to 18q21.1, or ERDA-1 (also known as Dir 1), which maps to 17q21.3. (cardiff.ac.uk)
Thus we conclude that in our sample, the previous RED associations are not a result of large CAG/CTG repeats at CTG18.1 or ERDA-1. (cardiff.ac.uk)

Anatomy1

Organisms2

Diseases19

Chemicals and Drugs17

Analytical, Diagnostic and Therapeutic Techniques and Equipment7

Psychiatry and Psychology2

Phenomena and Processes31

Information Science3

Health Care1

Gene40

Mutation12

Chromosome3

Microsatellites4

Phenotype1

Cytosine-adenine-guanine1

Huntington's1

Intermediate4

Genome6

Polymorphism3

Polymerase chain re4

FMR11

Genotype2

Individuals6

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Homozygous3

Onset3

Penetrance1

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Genomic2

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Intronic2

Loci1

Interruptions2

Mutant1

Symptoms1

Premutation2

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Unstable2

Populations2

Frataxin levels2

Instability2

Inheritance1

Variant2

Segments1

Anticipation2

Methylation1

Normal2

Locus1

Sperm1

Imperfect1

Sequence2

Genetics1

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Motif1

Fuchs2

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Zinc1

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