Tandem repeat facts for kids

Kids Encyclopedia Facts

Tandem repeats occur in DNA when a pattern of nucleotides is repeated. The repeats sit next to each other, in tandem. These are multiple copies of the same base-pair sequence lying end-to-end.

An example would be:

in which the sequence ATTCG is repeated three times.


If 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…).

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

The repeat unit copy number is variable. This is a variable number tandem repeat (VNTR).


A tandem repeat patternt 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 in the chromosomal DNA.

Tandem repeat Facts for Kids. Kiddle Encyclopedia.