Kentaro Kasai, Kanako Yoshida, Koji Fujii, Hiroaki Senju, Kazumasa Sekiguchi, Hajime Sato, Sueshige Seta,
and George F. Sensabaugh
National Research Institute of Police Science, Tokyo, Japan

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PCR-based STR typings are widely investigated using multiplex STR systems as the forensic DNA typing from degraded samples such as aged bloodstains, decomposed tissues and so on. However, it is difficult to set the best condition of the PCR amplification and the gel electrophoresis on each locus of the multiplex system, especially from forensic samples. So, we have selected the single systems in which amplified products from the degraded samples are small for the successful DNA typings.

CSF1PO locus on which 8 alleles are observed in Japanese population is useful for DNA typing to identify Japanese people. However, the sizes of amplified products are too large to detect from degraded samples on conventional CSF1PO typing, which is designed for multiplex system use. Therefore, we designed new primers which amplify CSF1PO locus as the sizes from 150 to 182 bp correspond to 7 to 15 repeats which are 115 bp shorter than conventional ones. New system was verified to detect CSF1PO types from aged bloodstain samples. Highly degraded DNA samples such as aged bloodstains over 30 years did not show any band detected even by the new system. However, CSF1PO types were detected from some bloodstain samples left over 16 years whose types were not able to be detected by the conventional system.

We are planning to use new CSF1PO system with TH01 and D1S80 systems for forensic DNA typing and also develop other single systems with shorter amplified sizes to detect from highly degraded samples such as hair and decomposed tissues.