What is DNA fingerprinting?
Just like your fingerprint is unique to you, the DNA sequence in your cells contains certain variations that makes it unique as well. In fact, only 0.1% of your genome differs from any other individual. DNA fingerprinting is a technique to identify individuals based on their DNA sequence. Let’s review the best method and tools in DNA fingerprinting.
What makes your DNA unique?
Short tandem repeats (STRs), or minisatellites, are locations in the chromosomes that contain short and repeated nucleotide sequences. These short sequences of repetitive DNA show greater variation from one person to the next than other parts of the genome. This variation is exhibited in the number of repeated units in the sequence. Since each variant act as an inherited allele, they can be used for parental or personal identification.
Since the length of a given minisatellite region varies between individuals, simultaneous detection of lots of minisatellites can be used to identify unique patterns in an individual. This is DNA fingerprinting. This technique is now used for several applications, such as forensics and parentage testing, but also zoology, botany and agriculture.
Usually, DNA fingerprinting include the following steps:
- DNA sampling and extraction
- STR analysis: PCR is used with a predefined set of primers labeled with fluorescent tags to target highly polymorphic regions of STRs (usually between 17 and 20 loci). Gel electrophoresis is then used to separate DNA fragments of different lengths. Each fragment passes by a laser which causes the fragments with fluorescent tags to glow with a specific color. The output is displayed as a series of colored peaks (as shown in the image below) highlighting the color. and length of each STR sequence.
- Image analysis
Tools for DNA fingerprinting
The resulting images produced by DNA fingerprinting are sometimes difficult to interpret, and multiple tools have been developed to simplify this task. The workflow to analyse DNA fingerprinting images generally include the following steps: Image Acquisition, pre-processing, lane detection, band detection, normalisation, and fingerpring comparison. Here are some great tools to analysis fingerprinting images:
- GelCompar II: A software tool for the analysis and comparison of electrophoresis patterns. It offers unique advanced features, including phylogenetic and dimensioning algorithms, group verification methods, database quality control techniques, GLP and database protection tools, history recording, ODBC and SQL compatibility, database sharing tools, client-server database exchange over Internet, and more.
- GelQuant Pro: A suite of core analysis tools for quantitative image analysis applications. It contains modules for 1D electrophoresis gel and western blot analysis, array/dot blot/slot blot analysis, colony counting & basic 2D spot measurement and general feature-based image analysis.
- PyElph: An open source Python based software for gel images analysis which can be used for different molecular biology or genetics studies. PyElph is able to analyze genetic variations of the DNA molecules from different species or populations.
Discover more DNA fingerprinting tools on our dedicated tool category.