Kentaro Kasai, Kanako Yoshida, Kazumasa Sekiguchi, Hiroaki Senju, Natsuko Mizuno, Ikuko
Sakia, Hajime Sato and Sueshige Seta
National Research Institute of Police Science, Tokyo, Japan
PCR based TH01 typing, one of the commercially available STR systems, is widely investigated for forensic DNA typing especially from degraded samples such as aged bloodstains, decomposed tissues and so on.
Detection of TH01 locus was carried out for 88 bloodstain samples left at room temperature for 15 to 34 years and detection of 5 loci of PM typing kit was also carried out for the same samples.
TH01 typing using denatured gel with allelic ladder worked well to detect alleles from DNA samples isolated from bloodstains left at room temperature within 20 years. TH01 alleles from bloodstains aged for 21 to 29 years were detected in some cases depending on the degree of degradation of sample DNAs. Highly degraded DNA samples such as aged bloodstains over 30 years did not show any band of amplified TH01 locus otherwise some samples appeared the positive result on the 3 loci in lower sizes of PM detection system because of their small amplification sizes. However, it is difficult to determine the types of loci of PM system when the S dot has no color because of the lack of a control dot for each locus. As performed using gel electrophoresis, STR system is better than the PM system regarding DNA typing for aged and decomposed samples in forensic cases.
A population study of TH01 locus is now being performed on 501 Japanese people.
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