Genetic Analyzer For STR (Short Tandem Repeat)

Using DNA identification technology helps crime-solving and criminal activities combat is a worldwide common consensus. It applies modern medical high-tech technology effectively in the criminal investigation. However, in the detection of many criminal cases, when a male criminal suspect leaves physical evidence at a crime scene, the DNA information data of the sample needs to be collected into the anti-crime DNA database.

The STR analysis will be introduced and applied to this article's crime scene analysis. STR stands for Short Tandem Repeat; the biotechnology DNA sequencing methods about 2-5 base pairs long/repeats are used to compare allele repeats at specific loci in DNA samples between two or more individuals. Since the STRs are repeated at a single location where there are identical in non-coding DNA regions that would not participate in protein synthesis, the STR analysis can be applied in Criminal cases and maternity or paternity matching.

Once the DNA sample is collected at a crime scene, the PCR  amplification (Polymerase Chain Reaction) is employed to make enough copies of that collected DNA sample to be more detectable. The three cyclic steps of PCR are applied, Denaturation to unzipping the DNA strands by heating hydrogen bonds, the forward and reverse primers are added up on the separated DNA stands to start Annealing, then the next step is DNA Extension by adding the Taq polymerase. Then after amplifying those DNA samples, we will focus on those regions of interest STR of the nucleotides. The PCR  amplified billions of the DNA samples are used to run through the Gel Electrophoresis. DNA is a negatively charged molecule, and those amplicon fragments are poured into the gel-filled capillary tube to do the gel electrophoresis. The speed at the negatively charged DNA fragments move across the gel electrophoresis toward to positive electrode in accordance with its size; smaller sizes with shorter repeats move faster than the ones with the larger size.

The STR region on the electropherogram can be analyzed using the software to determine the genotype. Everyone's genotype can be expressed by two copies, indicating the Short Tandem Repeats in copies from his or her mother and father. Superyears honor 1816 Genetic Analyzer performed the gel electrophoresis in the electropherogram below. It is essential to know that people inherit two copies of every gene (one from his/her father and one from his/her mother). Therefore, the gene may be homozygous, which inherited the same version from each parent, is presented with one peak pattern as shown below electropherogram. On the other hand, some genes are heterozygous, which shows two peaks in the electropherogram, indicating that they came from difcerent version of each parent.

Identifiler Plus Reagent kit sample detection results on Honor 1816

Electrophoresis was performed by using Nanjing Superyears Gene Technology Co., 

Ltd. Genetic Analyzer Honor Series 1816 by Identifiler Plus kit, and the data generated 

were analyzed using Genemapper-IDX.

Analytical Forensic Instrument Parameters

Genetic Analysis Test for STR Advantages