New markers for old stains: stable mRNA markers for blood and saliva identification from up to 16-year-old stains

Abstract

In forensic science, the unequivocal identification of the cellular origin of crime scene samples used for DNA profiling can provide crucial information for crime scene reconstruction. We have previously shown that various mRNA markers from genes with expression patterns specific for blood and saliva can be established from whole-genome expression analysis of time-wise degraded samples and were stable enough to specifically identify blood and saliva stains up to 180 days of age. Here, we showed that nine blood-specific and five saliva-specific mRNA markers can be amplified successfully and reliably in much older blood (13-16 years) and saliva (2-6 years) stains, respectively, suggesting their suitability for tissue identification in forensic case work. Moreover, our findings imply that forensic RNA testing can be reliable and robust if degraded samples are considered in the marker ascertainment procedure, with promising expectations beyond tissue identification purposes.

Selection of highly specific and sensitive mRNA biomarkers for the identification of blood

“…A number of mRNA markers have been identified for the forensically most relevant body fluids: blood, saliva, semen, vaginal secretions and menstrual blood [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. RNA is notorious for its rapid post-mortem and in vitro decay, but several reports have pointed out an unexpectedly high stability of RNA in forensic stains [18][19][20].…”

“…Blood was chosen for its easy availability, stability and the number of reported markers [6][7][8][9][10][13][14][16][17][19][20]. The following blood markers were included in the study: HBA and HBB are the alpha-and betasubunits of hemoglobin A [21,22]; aminolevulinate synthase 2 (ALAS2) is an erythroid-specific mitochondrial enzyme, that catalyzes the first step in the heme biosynthetic pathway [23]; CD3 gamma molecule (CD3G) is part of the T-cell receptor-CD3 complex, which plays an important role in coupling antigen recognition to several intracellular signal-transduction pathways [24]; ankyrin 1 (ANK1) is an erythrocyte membrane protein, which provides the primary linkage between the membrane skeleton and the plasma membrane [25]; the erythroid form of porphobilinogen deaminase (PBGD) is the third enzyme of the heme biosynthetic pathway [26]; β-spectrin (SPTB) is an erythrocyte membrane protein [27]; Aquaporin (AQP9) is a water channel protein expressed in peripheral leukocytes [28].…”

Body fluid identification in forensics

“…Although a number of mRNA markers have been proposed as http://bmbreports.org BMB Reports sensitive and specific methods for forensic body fluid determination, and have also proven their stability successfully in samples over long periods of time, additional environmental conditions such as humidity and temperature are expected to influence mRNA stability (39,40). Therefore, recently, micro-RNA (miRNA) markers have started to be explored as an alternative tool for forensic body fluid identification (52)(53)(54).…”

An Investigation of Various Tissue Specific mRNA Markers in Body Fluid Identification

“…Ör-neğin; bir çalışmada, 15 yıllık bir kan lekesinden RNA izolasyonu yapılabildiği, diğer iki çalışmada da 16 ve 23 yıllık kan lekelerinden mRNA profilleme yapılabildiği belirtilmiştir. [39][40][41] Benzer şekilde, 16 yıllık tükürük lekelerinde de mRNA profilleme yapılabildiğini bildiren çalışmalar bulunmaktadır. Çeşitli koşulların etkisinin test edildiği bir çalış-mada ise olumsuz çevre koşullarına maruz kalmış lekelerde, 547 güne kadar yeterli kalite ve miktarda RNA elde edilebildiği bildirilmiştir.…”