Tandem repeat facts for kids

Tandem repeats happen in your DNA when a specific pattern of nucleotides is repeated over and over. Imagine a short word like "CAT" being repeated many times, like "CATCATCATCAT". In DNA, these repeated patterns sit right next to each other, one after the other. They are like multiple copies of the same DNA sequence, lined up end-to-end.

For example, if you see the DNA sequence: ATTCG ATTCG ATTCG, the pattern "ATTCG" is repeated three times.

What Are Different Kinds of Repeats?

Scientists have special names for different lengths of tandem repeats:

• If the repeated pattern is between 10 and 60 nucleotides long, it's called a minisatellite.
• If the repeated pattern is shorter than 10 nucleotides, it's called a microsatellite or a 'short tandem repeat'.

Repeats by Number of Nucleotides

• When exactly two nucleotides are repeated, it's called a dinucleotide repeat. An example would be: ACACACAC… (where "AC" is repeated).
• When three nucleotides are repeated, it's called a trinucleotide repeat. An example is: CAGCAGCAGCAG… (where "CAG" is repeated). Sometimes, having too many of these repeats can affect a person's health.

The number of times a pattern repeats can be different from person to person. This is why they are sometimes called "variable number tandem repeats" (VNTRs).

How Are Tandem Repeats Used?

Tandem repeats are very useful for understanding a person's unique genetic information.

Finding Family Connections

These patterns can help figure out who is related to whom. Because the number of repeats varies between people, scientists can compare these patterns to see if individuals share common ancestors. This is often used in genealogical DNA tests to trace family trees.

DNA Fingerprinting

Tandem repeats are also used in something called genetic fingerprinting or DNA profiling. This is a way to identify individuals based on their unique DNA. Scientists look at the tandem repeats in a person's DNA to create a unique "fingerprint" that is almost like a barcode for that person. This is very helpful in many areas, like identifying people or solving mysteries.

See also

In Spanish: Repeticiones en tándem para niños