Editing Tandem repeat (section)

==Terminology==
All tandem repeat arrays are classifiable as [[satellite DNA]], a name originating from the fact that tandem DNA repeats, by nature of repeating the same nucleotide sequences repeatedly, have a unique ratio of the two possible nucleotide base pair combinations, conferring them a specific mass density that allows them to be separated from the rest of the genome with density-based laboratory techniques, thus appearing as "satellite bands". Albeit, a tandem repeat array could not show up as a satellite band if it had a nucleotide composition close to the average of the genome.<ref>{{Citation |last=Brown |first=Terence A. |title=Genome Anatomies |date=2002 |work=Genomes. 2nd edition |url=https://www.ncbi.nlm.nih.gov/books/NBK21120/ |access-date=2025-01-01 |publisher=Wiley-Liss |language=en}}</ref>

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.<ref>{{cite journal |vauthors=Oki E, Oda S, Maehara Y, Sugimachi K |title=Mutated gene-specific phenotypes of dinucleotide repeat instability in human colorectal carcinoma cell lines deficient in DNA mismatch repair |journal=Oncogene |volume=18 |issue=12 |pages=2143–7 | date=March 1999 |pmid=10321739 |doi=10.1038/sj.onc.1202583|doi-access=free }}</ref>

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 between 10 and 60 nucleotides are repeated, it is called a [[minisatellite]]. Those with fewer are known as [[Microsatellite (genetics)|microsatellite]]s or [[short tandem repeat]]s.

When much larger lengths of nucleotides are repeated, on the order of 1,000 nucleotides, it is called a [[macrosatellite]].

When the repeat unit copy number is variable in the population being considered, it is called a [[variable number tandem repeat]] (VNTR). [[Medical Subject Headings|MeSH]] classifies variable number tandem repeats under minisatellites.<ref>{{MeshName|Variable+Number+of+Tandem+Repeats}}</ref>