minisatellite DNA

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minisatellite DNA

a form of polymorphic DNA, comprising a variable number of tandem repeats, with repeat units of up to about 100 NUCLEOTIDES in length, but typically 15–20bp. In humans, minisatellites form clusters up to about 5kb in length and are highly polymorphic due to the variation in repeat number. Telomeric DNA (see TELOMERE is an example of minisatellite DNA.

Minisatellite DNA is also called a VARIABLE NUMBER TANDEM REPEAT (VNTR).

The variability in repeat number at a specific VNTR LOCUS, makes analysis of minisatellite DNA useful for DNA FINGERPRINTING. The repeat region is often flanked by specific RESTRICTION ENZYME sites, so that it can be cut out of the chromosome and the number of repeats determined by a Southern blot (see SOUTHERN TRANSFER) and HYBRIDIZATION with a PROBE containing the repeat sequence. The DNA profile (fingerprint) generated can be individual-specific. If a number of different VNTR loci are analysed in this way the fingerprints become more discriminatory, making them particularly useful in DNA FORENSICS.

Another type of tandemly repeated DNA is the MICROSATELLITE. Microsatellite clusters are smaller than minisatellite clusters.