Increasing Allele Detection by Altering the Quantity of Internal Lane Standard

• NCJ Number: 249392
• Author(s): Jessica M. Esparza Ph.D., Monnie Michalik M.S.F, Mary Jones Dukes M.S., Patrick Wojtkiewicz Ph.D.
• Date Published: September 2015
• Length: 0 pages
• Agencies: NIJ-Sponsored
• Award: FY2011 Forensic DNA Backlog Reduction Program - State of Louisiana

Annotation

Because all samples subjected to capillary electrophoresis use internal lane standard (ILS), this study investigated the consequence of varying the volume of ILS and its effects on allele peak heights and number of alleles detected.

Abstract

Electrokinetic injection (EI) is the primary method used in forensic laboratories to load amplified PCR product in capillary electrophoresis for short tandem repeat (STR) fragment separation. Results of the current study show that when the volume of ILS is reduced, the average peak height and number of alleles increased, thereby increasing the sensitivity of the detection method. Sizing anomalies were observed; however, they did not adversely affect accuracy and precision. The method developed in this study offers a simple and universal procedure to increase the alleles detected in forensic STR analysis. Reducing the volume of ILS to achieve greater sensitivity is applicable to all STR amplification kits and capillary electrophoresis instruments currently used in forensic DNA analysis. (Publisher abstract modified)