If the loop out structure is formed from the sequence on the daughter strand this will result in an increase in the number of repeats. (wikipedia.org)
Generally, the larger the expansion the more likely they are to cause disease or increase the severity of disease. (wikipedia.org)
Processes2
When a DNA trinucleotide repeat sequence is damaged, it may be repaired by processes such as homologous recombination, non-homologous end joining, mismatch repair or base excision repair. (wikipedia.org)
A total of 4,761 perfect and 6,583 imperfect SSRs were present in 3,781 genes (14.11% of the total), corresponding to an overall density across the gene space of 32,5 and 44,9 SSRs/Mbp for perfect and imperfect motifs, respectively. (researchgate.net)
This graph shows the total number of publications written about "DNA Repeat Expansion" by people in UAMS Profiles by year, and whether "DNA Repeat Expansion" was a major or minor topic of these publications. (uams.edu)
Development1
Detection of TNRs was made difficult by limited technology and methods early on, and years passed before the development of sufficient ways to measure the repeats. (wikipedia.org)
Location1
Repeat composition and location are used to determine the mechanism of a given expansion. (wikipedia.org)
As with many other tandemly repeated microsatellite sequences, pathogenic TNRs are highly unstable in both the somatic and germ cell lineage, leading to expansions and contractions in the length of the repeats in successive cell or individual generations. (bmj.com)
Pathogenic1
However, pathogenic loci bear expanded alleles of up to several hundred or even thousand repeats in severe cases. (bmj.com)
In 1991, for fragile X syndrome, the fragile X mental retardation 1 (FMR-1) gene was found to contain a CGG expansion in its 5' untranslated region (UTR). (wikipedia.org)
10 These factors are not mutually exclusive and include the purity and length of the repeated sequence, 7, 11 age of individuals, 6, 7 mitotic drive, 12 the relative position of the TNR with respect to adjacent origins of DNA replication, 13 and mutations in genes involved in DNA repair, replication, and recombination. (bmj.com)
To test this hypothesis, we analysed normal length TNR sequences at a single repeat resolution by radioactive PCR and denaturating polyacrylamide gels, using DNA from multiple single cell clones expanded in the presence or absence of mitomycin-C (MMC), a mutagenic agent able to induce interstrand DNA cross links, strand breaks, and replication blockage. (bmj.com)
Alleles2
In addition, much of the evidence for the mechanisms that are thought to produce repeat expansion in pathological TNRs are dismissed as irrelevant for normal alleles. (bmj.com)
After the breakthroughs, the four mechanisms for TNRs were determined, and more types of repeats were identified as well. (wikipedia.org)
Detection of TNRs was made difficult by limited technology and methods early on, and years passed before the development of sufficient ways to measure the repeats. (wikipedia.org)
6- 8 Expansions in the number of TNRs are known to be a molecular basis of genetic anticipation, 9 the progressively earlier age of onset of a disease with increasing severity in successive generations. (bmj.com)
In addition, a CAG expansion was located in X-linked spinal and bulbar muscular atrophy (SBMA) sequences. (wikipedia.org)
31 Therefore, we have hypothesised that mutagenic stress could result in an induction of instability of unexpanded TNR sequences, leading to an increase in the frequency of spontaneously occurring contractions/expansions in repeat number. (bmj.com)
Pairs1
Onwards from 1995, it was also possible to observe the formation of hairpins in triplet repeats, which consisted of repeating CG pairs and a mismatch. (wikipedia.org)
Mechanisms1
Other proposed mechanisms for expansion and reduction involve the interaction of RNA and DNA molecules. (wikipedia.org)
Appears2
It appears that expansion of these repeats is more common than reduction. (wikipedia.org)
The traditional methods of developing simple sequence repeat (SSR) markers are usually time-consuming and labor-intensive. (biomedcentral.com)
Found2
During the decade after evidence that linked TNR to onset of disease was found, focus was placed on studying repeat length and dynamics on diseases, as well as investigating the mechanism behind parent-child disease inheritance. (wikipedia.org)
By using these markers, we found that the intergroup gene diversity of J. curcas was greater than the intragroup diversity, and that the domestication of the species probably occurred partly in America and partly in Hainan, China. (biomedcentral.com)