You know from your reading that the current DNA technology b

You know from your reading that the current DNA technology being used deals with short tandem repeats. What is the most commonly used repeat length? What happens if the repeat is too short or too long?

Solution

Short tandem repeats (STRs), which are sometimes referred to as microsatellites or simple sequence repeats (SSRs), are accordion-like stretches of DNA containing core repeat units of between two and seven nucleotides in length that are tandemly repeated from approximately a half dozen to several dozen times.Short tandem repeat (STR) typing methods are widely used today for human identity testing applications including forensic DNA analysis. Following multiplex PCR amplification, DNA samples containing the length-variant STR alleles are typically separated by capillary electrophoresis and genotyped by comparison to an allelic ladder supplied with a commercial kit.

The utility of miniSTR assays has been confirmed in intra- and interlaboratory studies involving degraded bone samples and aged blood and saliva stains. Success rates in recovering information from compromised DNA samples improve with miniSTR systems compared with conventional STR kits