Evaluation of a co-extraction method for real-time PCR-based body fluid identification and DNA typing

Body fluid identification and individual identification are an important series of tests in usual criminal investigations. Recent reports have demonstrated a new approach using DNA/RNA co-extraction methods in which RNA for body fluid identification and DNA for short tandem repeat (STR) typing are extracted simultaneously from the same sample. This study evaluated a standard co-extraction kit, the AllPrep (R) DNA/RNA Mini Kit, in order to demonstrate the availability of the co-extraction procedure for those real-time polymerase chain reaction-based body fluid identification methods that we have validated previously. We demonstrated that the use of the Allprep Kit, for which we adjusted the lysis temperature to 56 C to improve extraction efficiency, can simultaneously extract sufficient RNA and DNA for body fluid identification and STR analysis; however, a longer incubation at a high temperature slightly affected the Delta Ct value of each target gene and appeared to be not as effective for DNA extraction from old stains as from 1-day-old stains. This method is promising for future forensic investigations because the use of this kit can reduce sample consumption for body fluid identification and DNA typing. (C) 2013 Elsevier Ireland Ltd. All rights reserved.