Simultaneous analysis of microRNA and DNA for determining the body fluid origin of DNA profiles

MicroRNAs can be specifically expressed in forensically relevant body fluids such as blood
or saliva. The aim of the study was to develop a simultaneous extraction and analysis
protocol that allows for the acquisition of a DNA profile and the identity of the body fluid
using a single process. DNA and microRNA were extracted from blood and saliva before
undergoing a cDNA synthesis step by using stem-loop reverse transcription PCR. The
resulting extracts containing DNA and cDNA synthesised from body fluid specific miRNA
markers then underwent standard STR analysis using a modified ABI AmpfSTR NGMSElect
kit. In all samples, a full DNA profile was obtained along with additional peaks
corresponding to the miRNA marker targeted. In all cases, blood samples profiled exhibited a
peak indicating the presence of the blood specific miRNA marker and the saliva sample
profiled exhibited a peak indicating the presence of the saliva specific miRNA marker