DNA Forensics Problem Set 2

Problem 2: The variation of VNTRs

The VNTR alleles analyzed in forensic DNA fingerprinting experiments are highly variable from individual to individual. How do the many VNTR alleles at a single locus differ from each other?


VNTR: Variable Number of Tandem Repeats

As the acronym for VNTR suggests, the variability or differences in VNTR alleles are in the "number of tandem repeats." A tandem repeat is a short sequence of DNA that is repeated in a head-to-tail fashion at a specific chromosomal locus.

Tandem repeats are interspersed throughout the human genome. Some sequences are found at only one site -- a single locus -- in the human genome. For many tandem repeats, the number of repeated units vary between individuals. Such loci are termed VNTRs. One VNTR in humans is a 17 bp sequence of DNA repeated between 70 and 450 times in the genome. The total number of base pairs at this locus could vary from 1190 to 7650.

The Biology Project
University of Arizona
Tuesday, August 20, 1996
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