Assessment of short tandem repeat profiling that obtained from some biological sources as forensic tool

In crime scenes the presence of some biological evidences such as body fluid (blood, saliva and semen) and keratinous tissue (nail clipping and hair) even epithelial cells, it may be the decisive limit in resolving many issues. In forensic laboratories, short tandem repeat (STR) markers are frequently employed. The present study aimed to evaluation STR profiling that obtains from some body fluids and keratinous tissues as forensic evidence. Ten samples from each blood, saliva, buccal swab and fingernail clippings were collected from different volunteers. Isolation of DNA was performed by using phenol- chloroform technique and quantities of DNA were measured by Quantifier ® Human DNA quantification kit in 7500 Fast Real-Time PCR System. All samples were typed using the Applied Biosystems kit for 15 autosomal STR loci as well as amelogenin. Results revealed that the mean DNA quantities were significant higher (P< 0.001) in the blood and buccal swab samples compared with saliva and fingernail clipping samples. Also, blood and buccal swab samples were appeared complete STR profiles (alleles appearance percentage100%). whereas, alleles appearance percentage range 33.3–100% for fingernails samples and 53.3–93.3% for saliva samples.

The partial STR profiles in most of saliva and fingernail clippings samples may related to the presence of lytic enzymes and polymerase chain reaction inhibiter in saliva samples and low quality of DNA isolated from fingernail clippings samples.