Forensic Testing – Casework Services – STR Analysis

Forensic Testing - Casework Services - STR Analysis

Short tandem repeat (STR) analysis is the most popular and most recommended method for genetic DNA identity comparisons. Essentially, the focus of STR testing is to obtain a DNA profile from some genetic evidence where the donor is unknown, and compare that profile to the profiles obtained from DNA samples where the donor is known in order to determine if a match exists. If it does, statistical analysis is performed to determine the significance or weight of that match.

The DNA Reference laboratory has validated the latest DNA extraction methods that allow for the ultimate in DNA recovery from inhibited samples. We incorporate the DNA IQ system utilizing Maxwell 16 Robotics from Promega Corporation to bypass most inhibitors using magnetic isolation technology. We have also validated standard phenol-chloroform organic methods under specific circumstances.

The DNA Reference laboratory was the first laboratory in the world to validate the Promega Plexor HY Quantification Kit using the Roche Lightcycler 480 Real Time PCR Instrumentation. Using this technology we are able to simultaneously detect the quantity of total DNA and male specific DNA present in a single DNA extract, useful for sexual assault samples where a mixture of male and female DNA exists. We use these values to dilute or concentrate the samples to a concentration ideal for amplification using the kits below.

The DNA Reference laboratory has validated amplification kits and systems from a variety of accepted vendors, offering its customers a choice if they have a preferred system. We offer tests using the following systems:

  • PowerPlex 16 Kit – Promega Corporation – 15 STR loci + Amelogenin Sex Indicator
  • PowerPlex 21 Kit –High Sensitivity and Inhibitor Resistance-20STR + a Gender Locus
  • PowerPlex 24 Fusion STR Kit. The most powerful STR kit on the market at the present time. Extremely sensitive and tolerant for PCR inhibitors.
  • PowerPlex Y-23 Kit – The maximum number of male gender loci available commercially.
  • PowerPlex 16 HS Kit – Promega Corporation – High Sensitivity 15 STR loci + Amelogenin Sex Indicator
  • PowerPlex 18D kit -Promega Corporation- High sensitivity and inhibitor resistance 17 STR loci Kit + Gender
  • Identifiler – Applied Biosystems – 15 STR Loci + Amelogenin Sex Indicator
  • Y-Filer – Applied Biosystems – 17 STR Loci on the Y Chromosome for Male Specific Testing

The DNA Reference laboratory uses the ABI 3130 capillary electrophoresis instrumentation for DNA detection, utilizing Genemapper software for DNA profile generation. This combination of technologies allows for extremely sensitive detection of amplified product and clear, concise results.

Our review process is extensive, following the FBI Quality Assurance and ISO 17025 standards to ensure that quality is assured and controls and reviews are appropriately implemented.

We offer this state of the art testing at pricing that would be equivalent to that charged by other private laboratories that use less powerful technology.

STR Analysis Services Offered

  • Sexual Assault Kit Testing (Separation of Sperm and Epithelial Fractions, PowerPlex 16 or HS)
  • Sexual Assault Kit Testing (Separation of Sperm and Epithelial Fractions, Identifiler or Y-Filer)
  • Standard Evidence Testing (PowerPlex 16, Identifiler, Y-Filer)
  • High Sensitivity Evidence Testing (PowerPlex 16 HS)
  • Touch Sample High Sensitivity Testing (PowerPlex 16 HS)
  • PowerPlex 18D kit for the maximum multiplexing and inhibitor resistance.
  • Standard Reference Sample Testing (PowerPlex 16, PowerPlex 16 HS, Identifiler, Y-Filer)