Minisatellite (VNTR)
Definition
A hypervariable genomic locus characterised by tandem repeats of a 10-60 bp core sequence, with the number of repeat units varying between individuals. Minisatellites were the targets of Jeffreys' original DNA fingerprinting probes (33.15 and 33.6). RFLP fragment length at a minisatellite locus reflects the number of repeat units between flanking restriction sites.
- Repeat unit size
- 10 to 60 base pairs
- Also called
- Variable Number Tandem Repeat (VNTR)
- Historical role
- Target of Jeffreys' original DNA fingerprinting probes 33.15 and 33.6
- Detection method
- RFLP, measuring restriction fragment length
Common questions
How do minisatellites differ from the microsatellites used in modern STR typing?+
Minisatellites have longer repeat units, 10 to 60 base pairs versus 2 to 6 for microsatellite STRs, and were originally typed by RFLP and Southern blotting rather than PCR amplification. STRs replaced minisatellites in casework because they amplify reliably from smaller, more degraded DNA quantities.
Why did minisatellite RFLP profiling fall out of routine forensic use?+
RFLP required relatively large amounts of high molecular weight DNA and was slow, technically demanding, and difficult to standardise for database searching across laboratories. PCR-based STR kits offered faster turnaround, smaller sample requirements, and easier interlaboratory comparison.
What made Jeffreys' minisatellite probes forensically significant?+
They revealed that the number of repeat units at these loci varied enough between unrelated individuals to produce an individualising banding pattern, which became the basis of the first DNA fingerprinting method used in a criminal case.
Related terms
- Microarray (Gene Chip / SNP Chip)
- A solid-phase hybridisation platform carrying thousands to millions of oligonucleotide probes at spatially registered positions. Hybridisation of a labelled target simultaneously queries...
- Molecular Hybridisation
- The formation of a double-stranded nucleic acid molecule from two complementary single strands, driven by hydrogen-bond formation between base pairs (A-T, G-C...
- mRNA Body-Fluid Profiling
- The RT-PCR-based descendant of Northern blotting: tissue-specific messenger RNA transcripts are reverse-transcribed and amplified from crime-scene stains to identify body fluid of...
- Southern Blot
- A technique (E.M. Southern, 1975) in which restriction-digested DNA fragments are separated by gel electrophoresis, transferred to a membrane, and hybridised with...
- Stringency
- The extent to which hybridisation conditions favour only perfectly complementary probe-target pairs over partially mismatched ones. High stringency (elevated temperature and/or low...
- Western Blot (Protein Immunoblot)
- SDS-polyacrylamide gel electrophoresis (SDS-PAGE) of proteins followed by electrotransfer to a PVDF or nitrocellulose membrane, then antibody-based detection of a specific protein...