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1. History
Before DNA testing, the discovery of the ABO blood type system by Austrian scientist Landsteiner in 1900 not only helped to treat patients and study about blood and blood types, but also helped investigators to trace crimes through blood traces, determine blood relations. However, the application of analyzing blood type systems only helps to exclude traces or people who are not related by blood, but it is not possible to confirm who the traces of blood belong to or whether they are related by blood.
However, it took 85 years later, in 1985, to determine the blood relationship. At that time, Alec Jeffreys and colleagues at the University of Leicester (UK) discovered the polymorphism of repeats in the human DNA molecule (Variable Number of Tandem Repeat - VNTR). Interestingly, it is worth noting that these loops in different individuals are not the same and they span across the DNA molecule.
Alec Jeffreys considers this a unique feature to distinguish one from the other. At the same time, these traits are also inherited according to Mendel's law, which is the scientific basis for determining blood relations. Thus, Alec Jeffreys' discovery is considered the first milestone that lays the foundation for DNA testing.
When did DNA testing first appear?
Next, also in 1985, Kary Mullis (1944 – 2019) invented the DNA molecular polyploidy reaction (Polymerase Chain Reation – PCR). With this reaction, from an initial very small amount of DNA, after 28-32 cycles, the amount of DNA increases to hundreds of millions of copies.
Therefore, it is very favorable for further studies, especially criminal samples that are often small and denatured. The invention of DNA polyploidy reaction is considered a breakthrough in science, especially in molecular biomedical research of the twentieth century. Therefore, Kary Mullis was awarded the Nobel Prize in 1993.
Since 1986, the British Royal Police began to apply DNA analysis techniques to identify the criminals.
A world-renowned case that first applied DNA technology was carried out in the UK in 1986. Two schoolgirls, Lynda Mann and Dawn Ashworth, both aged 15, were raped and murdered at different times, in 1983 and 1986 in the Leicestershire area. The circumstances and nature of the case were almost the same, so investigators believed that it might be the same perpetrator.
During the investigation, a local man named Richard Buckland, 17 years old, confessed to raping and killing Dawn Ashworth. The local police immediately collected a sample of this person for DNA testing, but the results did not match the sperm samples collected from the two victims.
Police had to collect more than 5,000 blood samples from male suspects aged between 17 and 34 in areas around the crime scene for DNA testing, but there was no match. The case seemed to be at an impasse.
After nearly a year at a bar, a woman overheard a man named Colin Pitchfork talking about how he tricked a friend into taking a blood sample in lieu of his own. Police immediately took a sample of his blood and examined his DNA. The results showed that his genotype exactly matched the traces in the two rapes. He was later charged and sentenced to life in prison.
In 1988, the US Federal Bureau of Investigation (FBI) also began applying DNA analysis techniques to identify criminals.
In October 1990, in the United States, the Human Genome Project (HGP) was officially launched. On February 12, 2001, HGP and Celera published the complete sequence of the human genome, a major event in the development of molecular biology in general and in the study of the human genome in particular. According to this publication, the number of genes in the human genome is about 35000 genes, including tens of thousands of STR (Short Tandem Repeat) loci that are applied to determine ancestry and trace individuals.
Colonel Ha Quoc Khanh (Former Director of the DNA Testing Center - Institute of Criminal Sciences; Former Deputy Director of the Institute of Criminal Sciences - Ministry of Public Security; Senior Scientific Advisor of GENTIS) shared about the history of DNA testing
In 1991, Prof. Thomas Caskey and colleagues at Baylor University, Texas, made a recommendation to use Short Tandem Repeat (STR) in criminal DNA testing. Accordingly, Promega Group and Perkin Elmer together with molecular biology company Roche have successfully manufactured STR commercial kits for use in DNA testing. STRs are superior to VNTRs because their repeats are only 2-5 base pairs and multiplex units are from 100 to 500 base pairs, capable of performing DNA ploidy reactions of many different STR locus. In particular, it is very suitable for samples with small quantities or poor quality such as criminal traces.
In 1992, Sasch Willuweit, together with Lutz Loewer and colleagues, researched and applied the Y sex chromosome to determine blood relationships. In terms of genetics, the Y chromosome is inherited only by the paternal lineage; therefore, the Y chromosome only analyzes and compares between people of the male gender to see if they have the same bloodline according to the paternal line. Subsequently, this group of authors built the YHRD online analysis tool to analyze and compare based on Y-STRs of human populations around the world.
In 2003, Szibor and colleagues studied and proposed the application of the X sex chromosome in determining blood relations. The application of sex chromosome X in the determination of blood relationship is considered an adjunct to the STR autosomal analysis method when this method cannot be conclusive, such as analyzing the blood relationship between father and daughter or grandmother-granddaughter in case the father is unable to provide a sample.
In 1993, the first STR kit was introduced and put into use; initially those were just kits using a single locus, then were Duplex kits such as TPOX/CSF1PO; triple-kit (Triplex) including TH01/F13A/FES or CFS1PO/TH01/TPOX (CTT)... But today, most laboratories use kits ranging from 16, 17, 18 or 24 STR locus. These kits are made by Promega, Thermo Fisher Scientific and Qiagen. In addition, some countries also manufacture domestic kits (Inhouse) such as GoldenEye 20A, Rapit 21Plex System or AGCU 21+1 STR kits of China; Spain's DNASE 21 kit...
In 1995, the British Royal Police was the first law enforcement agency in the world to build a criminal DNA archive. Accordingly, all offenders sentenced to imprisonment are sampled for storage in the database.
In 1996, the US Federal Bureau of Investigation (FBI) began using mitochondrial DNA (mt DNA) to analyze DNA from human remains samples to determine maternal blood relations. However, this is a complex technique, which does not always achieve the desired results, but depends a lot on the quality of the sample and other professional conditions.
Then, in 1998, the FBI also began building a criminal DNA archive using the CODIS kit (13 STR locus). By 2017, the CODIS kit had increased to 20 STR locus.
According to the International Criminal Police Organization (Interpol), by 2019, 70 Interpol member countries had built criminal DNA archives.
In Vietnam, in 1999, the Institute of Criminal Sciences under the Ministry of Public Security was the first public agency to implement DNA testing to serve the professional work of the industry with synchronous and up-to-date equipment of international level at that time.
In 2007, in Copenhagen, Denmark, the International Society for Forensic Genetics (ISFG) proposed the possibility of applying Single Nucleotide Polymorphism (SNP) to criminal science. By 2014, Illumina (USA) used Next Generation Sequencing (NGS) equipment to analyze SNPs along with STRs in individual traceability, determining blood and racial relationships. If analyzed from 50 to 90 SNPs, the reliability would be equivalent to that of the CODIS kit (USA) with 13 autosomal STR locus.
Up to now, most countries in the world have introduced DNA technology into the testing work to serve the investigation, prosecution and trial of crimes as well as meet the social requirements. Therefore, research and manufacturing companies in the world have also launched many analytical equipment and test kits for this field. At the same time, the legal corridor has also been completed to ensure the legality and science of the field of DNA testing.
DNA testing was born at first mainly to solve criminal cases. Therefore, the term Forensic DNA (understood as criminal DNA) was born and has existed until now. Today, however, the subject of DNA testing is much broader.
2. Development tendencies of DNA testing
Until now, the use of STR loci (including autosomal STR, Y-STR, X-STR) along with capillary electrophoresis (CE) is considered the gold standard in DNA testing. However, with the development trend of technology and from the reality of criminal DNA testing, experts as well as technological companies have oriented the development of this field of testing in the future.
First of all, increasing the number of loci in the analysis kits to increase reliability and limit errors when analyzing cases of incest, close relatives or cases with mutations.
GENTIS - A well-trusted DNA testing center in Vietnam
Analysis of SNPs combined with STR loci to maximally use characteristics for identification of individuals, blood relations, phenotypes and races based on NGS (Next Generation Sequencing) technology. SNPs have outstanding advantages over other markers because SNPs have the advantage of very few mutations, which is suitable for analyzing criminal patterns due to the small amount of DNA or broken and denatured DNA. SNPs are not only applicable for the analysis of criminal patterns but also used in non-invasive bloodline determination and other medical applications.
Develop STR mini kits to fit criminal patterns
Improving technology, equipment and kits for rapid DNA testing. This is a new trend in developed countries to trace "hot traces" in criminal cases as well as border security control on immigration. Accordingly, a number of new devices have been born to meet this requirement.
With the DNA rapid testing equipment, there is no need for an outside laboratory and some other supporting equipment, but only the main equipment which can be easily transported, then the assessor only needs to put the sample into the device, and after 90 minutes it will produce a full genotype. The known devices include ANDE (Accelerated Nuclear DNA -Equipment), RapitHit, or SeqStudio Genetic Analyzer.
The operating principle of this type of device is that the entire analysis process from DNA extraction to analysis to produce a genotype is integrated in a chip or cartridge along with the analysis software. These devices are capable of analyzing 5 samples for a single run with 24-27 STR loci data, including both sex determination loci (Amelogenin) and Y-STR. Rapid DNA tests have been used in the US and some developed countries around the world.
In addition, some authors have also proposed the application of Indel (Insert/Delete) in DNA testing. However, these markers have not been widely applied.
Colonel Ha Quoc Khanh
