Messenger RNA based skin identification using skin specific markers from fingerprint impressions

Ogbonnaya Onyekachi,Frank Tochukwu,Janet Ndidiamaka,Nneoma Onyekachi,Omolade Omowumi

doi:10.5937/kgjsci2042085o

Abstract

The study of forensic science may be complex especially in the areas of nucleic acids and trace evidence. Oftentimes, forensic scientists recover minute quantities of biological material from scenes therefore the need to generate the genetic profiles and identify the source of the material. The aim of this study is to determine the expression levels of skin-specific gene markers - Loricrin (LOR), Corneodesmosin (CDSN) and Keratine 9 (KRT9), on fingerprint impressions of individuals of specific age group and genders. Thumbprints were collected using labelled frosted microscope glass slides and cello tapes. Messenger RNA was extracted from the samples, converted to cDNA and amplified by qPCR with its specific primer sequences. In males, RNA yield was higher in the slide (26.96±8.68) compared to cello tape (18.32±4.52) while the reverse was the case in the females. Across gender, RNA purity and yield were higher in males than females. In males, KRT9, LOR and CDSN genes were more expressed using frosted slide (37.03±0.77, 40.46±2.66, 35.62±2.82) compared to cello tapes (35.33±0.3, 32.11±0.5, 35.28±0.86) respectively. In females, LOR, CDSN and ACTB genes were more expressed using frosted slides (36.26±0.8, 37.37±0.58, 26.63±0.12) compared to cello tapes (35.52±1.01, 35.57±3.22, 26.57±1.18) respectively. Across gender, LOR, KRT9 and ACTB genes were more expressed in males than females while CDSN was more expressed in females than males. The expression levels of CDSN and ACTB genes were significantly (p≤0.01) correlated. This study shows that mRNA markers LOR, CDSN and KRT9, analysed via the RT-qPCR assays, are highly suitable for identifying skin cells even in small traces.

Highlights

There is a strong trend in molecular forensics for the development of alternative techniques to identifying the cellular origin of biological samples and trace evidence collected at crime scenes (HALL et al, 2013)
The reverse was the case for the ACTB gene which showed that the samples taken on cut cello tapes expressed more of this gene (27.05 ± 0.11) than the samples collected on frosted slides (26.94 ± 0.67)
LOR, CDSN and ACTB genes were more expressed in samples taken on frosted slides (36.26 ± 0.8, 37.37 ± 0.58, 26.63 ± 0.12) than those taken on cut cello tapes (35.52 ± 1.01, 35.57 ± 3.22, 26.57 ± 1.18) respectively

Summary

Introduction

There is a strong trend in molecular forensics for the development of alternative techniques to identifying the cellular origin of biological samples and trace evidence collected at crime scenes (HALL et al, 2013). In order for forensic scientists to overcome the limitations faced currently using for example classical body fluid identification approaches, the use of messenger RNA (mRNA) profiling has been suggested to supplant conventional methods for body fluid identification (JUUSOLA and BALLANTYNE, 2003). This ensures the production of unique gene expression patterns for each cell type which is evidenced by the presence and abundance of specific mRNAs (ALBERTS et al, 1994). The variation within and between individual skin-specific mRNA as has been observed in some previously described cases, which complicate the determination of the presence of skin using certain markers, has pointed to the need for further investigation (HALL et al, 2013)

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Discussion

Conclusion