Variable-Number Tandem Repeat (VNTR)
Definition
A region of DNA where a short sequence is repeated a variable number of times. The number of repeats at multiple locations generates a DNA profile. Used in first-generation DNA fingerprinting and still present in modern STR-based profiling.
- Structure
- Tandem repeat unit, longer than STR repeats (often 10 to 100+ bp)
- Historical role
- Basis of Alec Jeffreys's first-generation DNA fingerprinting (1984-85)
- Detection method
- Restriction Fragment Length Polymorphism (RFLP) analysis
- Modern status
- Largely superseded in casework by STR-based multiplex profiling
Common questions
Why did STR profiling replace VNTR-based RFLP profiling?+
VNTR loci require larger, less degraded DNA samples and RFLP analysis is slow and hard to fully automate. STR loci are much shorter, so they amplify reliably from small or degraded samples using PCR, and the method is amenable to fast, standardised multiplex kits.
Is VNTR analysis still used anywhere in forensic genetics today?+
Direct RFLP-based VNTR typing is essentially retired from routine casework, but some VNTR-type loci, including longer tandem repeats and certain Y-chromosome markers, still see use in specialised research or lineage studies where the longer repeat unit is informative.
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