title: Estimation of the detection rate in STR analysis by determining the DNA degradation ratio using quantitative PCR.
abstract: Performing short tandem repeat (STR) analysis from degraded DNA is a challenge for forensic biologists. For assessing the quality and quantity of DNA, we developed quantitative PCR assays to determine the extent of DNA degradation. Quantitative PCR assays using primers that generate two sizes of amplicons from the same region of genomic DNA were used to determine the extent of DNA degradation. These quantitative PCR assays were used with artificially degraded DNA and degraded DNA extracted from aged bloodstains. Increased DNA degradation correlated with a decrease in the number of detectable loci in STR analysis. The extent of DNA degradation and the number of loci detected by STR analysis varied depending on the method of degradation. The extent of degradation of DNA extracted from aged bloodstains correlated well with that of DNA artificially degraded by DNase I in the presence of Mn(2+). Thus, determination of the extent of DNA degradation was helpful for estimating the number of detectable loci. Furthermore, this estimation method is expected to save time and labor, and is particularly suitable when only a limited amount of DNA can be extracted from casework samples.
authors.affiliation: National Research Institute of Police Science, Kashiwa, Chiba, Japan. tetsushik@nrips.go.jp
authors.forename: Tetsushi
authors.initials: T
authors.lastname: Kitayama
authors.forename: Koji
authors.initials: K
authors.lastname: Fujii
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Nakahara
authors.forename: Natsuko
authors.initials: N
authors.lastname: Mizuno
authors.forename: Kentaro
authors.initials: K
authors.lastname: Kasai
authors.forename: Naoto
authors.initials: N
authors.lastname: Yonezawa
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Sekiguchi
mesh_terms: D001801:Blood Stains; D053836:DNA Degradation, Necrotic; D017931:DNA Primers / Q000032:analysis; D053803:Forensic Genetics / Q000379:methods*; D006801:Humans; D018895:Microsatellite Repeats; D060885:Multiplex Polymerase Chain Reaction / Q000379:methods; D011180:Postmortem Changes
chemical_list: D017931:DNA Primers