NCJ Number
205134
Journal
Journal of Forensic Sciences Volume: 49 Issue: 2 Dated: March 2004 Pages: 250-254
Date Published
March 2004
Length
5 pages
Annotation
This study examined whether amplifying DNA samples at lower annealing temperatures balances the peak heights observed in rare genomic sequence polymorphisms.
Abstract
The field of human identification extensively utilizes polymerase chain reaction (PCR)-based STR DNA typing systems. Under most conditions, the amplicon yield from both alleles of a STR locus is equivalent. However, under some conditions, rare genomic sequence polymorphisms co-localize with primer sets to induce an allele imbalance. In order to improve the poor data quality resulting from polymorphisms, the authors reamplified two DNA samples that showed strong disparity in amplitude peak height of heterozygous peaks at the loci vWA and FGA. Genotyping was performed with AmpF/STR Profiler Plus and PowerPlex 16. The reamplification process utilized a reduced annealing temperature during the thermal cycle, which resulted in an improvement in the primer-binding efficiency at the mismatch. Moreover, the employment of an alternative multiplex enhanced the data from each of the two samples. The authors conclude that reducing the annealing temperatures during the thermal cycle mitigates the problem of imbalanced allele amplitudes. Thus, the technique may have wide application for improving poor data quality suspected of originating from polymorphisms. An important determinate for the use of this approach may be the position of the mismatch within the primer. Tables, figures, references