NCJ Number
228509
Journal
Journal of Forensic Sciences Volume: 54 Issue: 5 Dated: September 2009 Pages: 1046-1054
Date Published
September 2009
Length
9 pages
Annotation
This validation study developed a protocol and interpretation guidelines before implementing the AmpFlSTR MiniFiler PCR Amplification Kit as a new technology designed to genotype degraded and/or inhibited DNA samples when the AmpFl STR Identifiler PCR Amplification Kit is unable to generate a complete genetic profile.
Abstract
The overall conclusion of the testing is that the MiniFiler kit is successful in generating robust and reliable DNA profiles from samples that exhibit DNA degradation or PCR inhibition; and it can be used in association with the Identifiler kit to obtain complete DNA profiles from challenged samples. An internal validation that followed the guidelines of the Scientific Working Group on DNA Analysis Methods (SWGDAM) observed a single instance of nonconcordance at the D21S11 locus between the kits, in which a 29.1 allele that was detected with Identifiler was not detected with the MiniFiler kit. This instance of nonconcordance resulted from the amplification of a sample with a rare microvariant allele. Amplification of all other samples resulted in full concordance across the two typing kits. The testing determined that caution should be taken in deducing component genotypes, given that heterozygous peak balance could be as low as 36 percent in a single source sample amplified with an optimum amount of input DNA. Another area that warrants consideration is in the interpretation of homozygote genotypes, largely due to the increase in sensitivity of the MiniFiler kit that enhances the possibility of observing stochastic effects. In contrast to the 0.5-0.75 ng of template DNA recommended by Applied Biosystems for the MiniFiler kit, the current testing determined that complete profiles could be obtained using a template DNA amount of 0.3 ng. This is approximately a six-fold increase in the sensitivity when compared to the 1.8 optimum input for Identifiler testing. 3 tables, 6 figures, and 21 references