STR analysis

The variable (polymorphic) nature of the STR regions that are analyzed for forensic testing intensifies the discrimination between one DNA profile and another.

[4][5] Forensic science takes advantage of the population's variability in STR lengths, enabling scientists to distinguish one DNA sample from another.

The system of DNA profiling used today is based on PCR and uses simple sequences[6] or short tandem repeats (STR).

These STR loci (locations on a chromosome) are targeted with sequence-specific primers and amplified using PCR.

[8] A study claimed 30 DIP-STRs were found to be suitable for prenatal paternity testing and roughly outlining biogeographic ancestry in forensics, but more markers and multiplex panels need to be developed to promote use of this original approach.

The SNPs from a larger panel gave significantly more accurate individual genetic self-assignment compared to any combination of the STR loci.

In practice, the risk of contaminated-matching is much greater than matching a distant relative, such as contamination of a sample from nearby objects, or from left-over cells transferred from a prior test.

Unexpected matches (or variations) in several control-samples indicates a high probability of contamination for the actual test samples.

Short tandem repeat (STR) analysis on a simplified model using polymerase chain reaction (PCR): First, a DNA sample undergoes PCR with primers targeting certain STRs (which vary in lengths between individuals and their alleles ). The resultant fragments are separated by size (such as electrophoresis ). [ 1 ]
A partial human STR profile obtained using the Applied Biosystems Identifiler kit