Tandem repeat

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Tandem repeats occur in DNA when a pattern of one or more nucleotides is repeated and the repetitions are directly adjacent to each other.[1]

An example would be:

ATTCG ATTCG ATTCG

in which the sequence ATTCG is repeated three times.

Terminology[edit]

When between 10 and 60 nucleotides are repeated, it is called a minisatellite. Those with fewer are known as microsatellites or short tandem repeats.

When exactly two nucleotides are repeated, it is called a dinucleotide repeat (for example: ACACACAC…). The microsatellite instability in hereditary nonpolyposis colon cancer most commonly affects such regions.[2]

When three nucleotides are repeated, it is called a trinucleotide repeat (for example: CAGCAGCAGCAG…), and abnormalities in such regions can give rise to trinucleotide repeat disorders.

When the repeat unit copy number is variable in the population being considered, it is called a variable number tandem repeat (VNTR). MeSH classifies variable number tandem repeats under minisatellites.[3]

Uses[edit]

Tandem repeat describes a pattern that helps determine an individual's inherited traits.

Tandem repeats can be very useful in determining parentage. Short tandem repeats are used for certain genealogical DNA tests.

DNA is examined from microsatellites within the chromosomal DNA. Minisatellite is another way of saying special regions of the loci. Polymerase chain reaction (or PCR) is performed on the minisatellite areas. The PCR must be performed on each organism being tested. The amplified material is then run through electrophoresis. By checking the percentage of bands that match, parentage is determined.

Polymorphic tandem repeats (alias VNTRs) are also present in microorganisms and can be used to trace the origin of an outbreak. The corresponding assay in which a collection of VNTRs is typed to characterize a strain is most often called MLVA (Multiple Loci VNTR Analysis).

In the field of Computer Science, tandem repeats in strings (e.g., DNA sequences) can be efficiently detected using suffix trees or suffix arrays.

Studies in 2004 linked the unusual genetic plasticity of dogs to mutations in tandem repeats.[4]

See also[edit]

References[edit]

  1. ^ Tandem Repeat at the US National Library of Medicine Medical Subject Headings (MeSH)
  2. ^ Oki, E.; Oda, S.; Maehara, Y.; Sugimachi, K. (1999). "Mutated gene-specific phenotypes of dinucleotide repeat instability in human colorectal carcinoma cell lines deficient in DNA mismatch repair". Oncogene 18 (12): 2143–2147. doi:10.1038/sj.onc.1202583. PMID 10321739.  edit
  3. ^ Variable Number of Tandem Repeats at the US National Library of Medicine Medical Subject Headings (MeSH)
  4. ^ Pennisi, E. (Dec 2004). "Genetics. A ruff theory of evolution: gene stutters drive dog shape". Science 306 (5705): 2172–2120. doi:10.1126/science.306.5705.2172. ISSN 0036-8075. PMID 15618495.  edit

External links[edit]