Higher Capillary Electrophoresis Injection Settings as an Efficient Approach To Increase the Sensitivity of STR Typing

• NCJ Number: 226895
• Journal: Journal of Forensic Sciences Volume: 54 Issue: 3 Dated: May 2009 Pages: 591-598
• Author(s): Antoinette A. Western M.Sc.; Jord H. A. Nagel Ph.D.; Corina C. G. Benschop B.Sc.; Natalie E. C. Weiler B.Sc.; Bas J. de Jong M.Sc.; Titia Sijen Ph.D.
• Date Published: May 2009
• Length: 8 pages
• Publication Format: Article
• Publication Type: Report (Study/Research)
• Language: English
• Country: United States of America

Annotation

This study used higher capillary electrophoresis injection settings in an effort to improve incomplete short tandem repeat (STR) profiles produced from low-level DNA samples under standard polymerase chain reaction (PCR) conditions.

Abstract

The study determined that incomplete STR profiles could be efficiently improved by increasing the capillary electrophoresis injection setting on an ABI3130XL from 3 kV/10 sec to 9 kV/15 sec. Peak heights (in rfu) increase on average six-fold. Amplification that used six additional PCR cycles increased the peak height on average 35-fold. The percentage of alleles detected in samples with 16 or 8 pg DNA input was similar upon boosted injection or more PCR cycles, although the average peak height was much lower in the 9 kV/15 sec injection profiles than those generated with an elevated cycle number. Boosted capillary electrophoresis is accompanied by the occurrence of allele dropouts and heterozygous peak imbalance, but does not require the use of increased stutter ratios. Boosted injection is suited to improving not only single-donor profiles but also the genotyping data of the minor component in mixtures. This method has been accredited for case work in the authors’ laboratory, the Netherlands Forensic Institute. The descriptions of materials and methods address DNA samples and STR profiling, capillary electrophoresis, and STR typing analysis. 5 tables, 4 figures, and 17 references