A pilot study of DNA yield from bloodstains on various surfaces using Phenol chloroform isoamyl alcohol (PCIA) and Chelex DNA extraction methods

Abstract

Presently, Short Tandem Repeats (STRs) based forensic DNA typing technology is being globally used in solving a diverse range of forensic cases such as paternity, identification of unknown dead bodies/skeletal remains, or suspect in a case of rape or mass rape. The technology has invaded its tentacles in almost all areas of criminal investigation in the last few decades. The present forensic DNA technology is based on capillary electrophoresis and utilizes short tandem repeats(STRs).On one hand, the technology is extensively used in the investigation of crime in highly sensitive cases, but on the another hand, obtaining DNA profile from forensic samples are highly challenging many times. Advent of PCR has been a boon for handling the challenging samples in forensic DNA analysis. The quality DNA profiles from challenging samples rely on the yield and quality of DNA, which is mainly dependent upon the method used for DNA extraction. Any specific method can never be thought of to be useful for all variety of samples. Still, Phenol Chloroform Isoamyl Alcohol (PCIA) organic extraction method has been proven to be useful for a wide variety of samples from the simplest saliva/blood to complex teeth and bone samples. In the present study, we compared the yield of DNA from blood stains recovered from various surfaces using the PCIA extraction method and Chelex DNA extraction methods and their compatibility with present-day STR based capillary electrophoresis typing. The mean value of DNA yield was found 50.5 ng/ µl and 32.25 ng/ µl by PCIA and Chelex DNA extraction methods, respectively. Overall, the highest yield was observed from all the tested samples from the PCIA method.